Abstract:
A drilling fluid for use in high oil viscosity formations containing tar, sand and oil entrained therein. The drilling fluid can be comprised of a polymer in an amount from between 0.05% and 5% by volume, a solvent in an amount from between 1% and 20% by volume and de-emulsifier in an amount from between 0.05% and 10% by volume.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/460,878, filed Apr. 8, 2003. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to drilling fluid and more particularly, the present invention relates to a drilling fluid composition adapted for use in high oil viscosity applications such as steam assisted gravity drainage (SAGD) and soak radial wells. 
     BACKGROUND OF THE INVENTION 
     In the existing technology, there is a wide variety of documents relating to drilling fluids and related materials. 
     It is known that drilling fluid, also referred to as drilling mud, is an important part of a drilling operation. The fluid is important to effect transport of debris, undesirable materials, gas etc. The fluid also functions to maintain lubrication and act as a coolant of the drill bit which experiences enormous force, friction and other stresses. 
     Typical of the presently used fluids is Kim Mud (a blend of polysaccharide polymers, calcium carbonate, calcium lignosulfonate). This material provides high carrying capacity by an inherent thixotropic viscosity. The composition may contain potassium ions for redncing volume increases (swelling). This has the advantage of preventing hydration of moisture sensitive clays. 
     D-limonene has also been used in drilling fluid and is particularly favored in view of the fact that it is a natural substance extracted from citrus rind. 
     Various amines have also been used to augment drilling fluid and provide a variety of advantages in different operating conditions. 
     It would be desirable to have a fluid capable of cleaning tar out of sand and incorporate the oil in an emulsion with subsequent release. Most of the fluids in current use are based upon preventing the tar (heavy oil) from entering the mud. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to provide an improved drilling fluid which is not limited as the prior art compositions. 
     A further object of one embodiment of the present invention is to provide a drilling fluid for use in drilling high oil viscosity formations (tar, sand and oil entrained therein), comprising:
         a water base viscosifying polymer in an amount from between 0.05% and 5% by volume;   a solvent in an amount from between 1% and 20% by volume; and   a de-emulsifier in an amount from between 0.05% and 10% by volume.       

     Advantageously, the composition is environmentally friendly, results in greater than 90% sand removal and is resistant to common drilling contaminants such as solids, gypsum, lime and salt inter alia. 
     Perhaps one of the most important features of the composition is ease with which the emulsion is broken to provide the oil and water as discrete phases. By enzymatic action, the emulsion is de-emulsified and this has been observed over a wide temperature range. In fact, the emulsion is broken in the absence of energy input, a significant feature. 
     A still further object of one embodiment of the present invention is to provide a method of recovering oil from tar sands containing tar, oil and sand, comprising:
         providing a composition containing a polymer, solvent for solving oil and tar from said tar sands and an emulsifier;   mixing compounds of said composition;   treating the tar sands with the composition to remove sand from the tar sands;   forming an emulsion with oil contained in treated tar sands where the emulsion is oil in water emulsion; and   de-emulsifying, under either energized or static conditions, the emulsion to release the oil as a separate phase from the water.       

     The composition in use has easily maintainable rheology and filtration control over a broad range of downhole operations. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following experiments are representative of the invention methodology and set forth experimental details in respect of the solution of the components of which the polymer system was made. 
     Experiment 1 
     An organic natural surfactant (Ho Flo) was evaluated in Kim Mud for its effect on tar sand. Testing was done at 30° C. It was found that Ho Flo at 0.1L/m 3  in Kim Mud improves the clumping of tar sand oil and prevents the stickiness of the oil to the testing container. 
     Experiment 2 
     As an extension of Experiment No. 1, further testing was performed on Ho Flo surfactant in Kim Mud regarding its ability to prevent the tar sand oil from sticking to steel. Lab results showed no apparent sticking of oil to steel in straight Kim Mud. Consequently, Ho Flo was not required. 
     Experiment 3 
     Solubility of two tar sand samples was tested in DMO 100 at room temperature (23° C.) and 35° C. At 23° C., DMO solubilized most of the tar leaving clean and freely moving sand. Temperature elevation to 35° C. resulted in higher solubility and complete removal of the tar from sand. 
     Experiment 4 
     Four lubricants were tested in Stable K (organic amine) mud to select the one with the least effect on tar sand. Testing was done at 23° C. and lubricant concentration of 1.5 and 3.0 kg/m 3 . 
     EZ Drill and EZ Drill II (biodegradable organic oils) appeared to soften the tar sand, although no obvious sign of dissolvability of tar sand was noticed. 
     Tork-trol II and EZ Slide produced no change in the tar sand appearance. 
     Experiment 5 
     Stable K mud, Gel Chem mud, Stable K/K 2 SO 4  mud and Polymer mud were evaluated for their ability to prevent blinding/sticking of bitumen from tar sands to screens. The testing temperature ranged from 5 to 20° C. and the screens used were 50, 70, 84 and 110 mesh. The Stable K mud was tested at 25 and 30° C. as well. 
     No blinding/sticking of bitumen to any screen occurred with any of the muds. The bitumen behaved the same in each mud. 
     Experiment 6 
     Various additives were tested in Polymer mud, Stable K mud and K 2 SO 4 /Gel mud to select the best combination that water wets the shaker screen and prevents sticking of tar sands to screen. 
     Drilltreat at 5 L/m 3  was the best additive improving the water wetting ability of all muds. K 2 SO 4  worked similar in a Gel mud and less in Polymer mud. Q&#39;Flow (Glycol) produced a softening of tar sands and dissolved some of the tar. 
     The second part of testing searched for an effective solvent of tar sands. Diesel, DMO 100 and HT-40N mixture of severely hydrotreated and hydrocracked base oil were tested at 23° C. The best solvent of tar from sand was Diesel with HT-40N being second best, DMO 100 was not found effective in removing the tar. 
     Experiments 7-9 represent lab work performed to develop a drilling fluid that solved the problems associated with drilling through tar sands. Thus, tar sand stickiness to equipment and shaker screen blinding was prevented with the new drilling fluid by removing the tar from the sand. 
     The idea behind the new drilling fluid was to formulate a direct emulsion where the external phase is water based and the internal phase is the organic solvent that removes the tar. Thus, the drilling fluid works by using the internal phase to clean the sand and keeping the removed oil in emulsion as fine drops. The emulsion is of loose structure and is readily broken or demulsified. 
     Experiment 7 
     The experiment relates to tests performed to select the organic solvent. 
     In order to find the best tar remover, over 50 products were tested at various concentrations. Q&#39;Clean™ (a mixture of petroleum hydrocarbons) was selected as the best tar remover. Generally speaking, the product comprises hydrogenated heavy petroleum naphtha together with an organic solvent. 
     While Q&#39;Clean™ was found as the tar remover and internal phase in the new drilling fluid, the external (continuous) phase selected was a Polymer/Stable K fluid. 
     No emulsifiers were required. Testing showed that emulsifiers had an adverse reaction by creating too small a drop of Q&#39;Clean™ in the drilling fluid reducing its ability for cleaning the sand. 
     The new drilling fluid, Polymer/Stable K/Q&#39;Clean™ was effective in removing the tar from the sand over a large range of temperatures, namely 5-30° C. 
     Experiment 8 
     This experiment sets forth work done to evaluate the performance of drilling fluid on a different sample of tar sands. 
     The Polymer/Stable K/Q&#39;Clean™ fluid was tested at temperatures between 5 and 30° C. on tar sand from ECR 3B 102 Leismer LSD 2/13-16-76-6w4. Testing confirmed that Polymer/Stable K/Q&#39;Clean™ fluid worked very well; the tar sand was cleaned at the temperature range indicated. 
     Experiment 9 
     This experiment related to developing the optimum formulation for the drilling fluid. The objective was to find the drilling fluid that dissolved and incorporated the tar, was least affected by contaminants and could be easily disposed of at the end of the well. 
     The project had 3 parts:
         designing and testing for the optimum formulation of drilling fluid with regards to tar removing ability;   testing the likely contaminants on the fluid to see if any fluid formulation adjustment is required; and   testing for emulsion breaking and oil phase separation for fluid disposal at the end of the well.       

     A new drilling fluid formulation containing Polymers/sized Calcium Carbonate/Q&#39;Clean™ was designed and tested. Various viscosifiers were tested at different concentrations with regards to mud rheology, cleaning ability and effect on emulsion breaking. 
     The following fluid formulation was selected fin its good rheology, fluid loss and tar sand cleaning ability: 
     
       
         
               
             
               
               
               
               
             
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 PolyTar ™ System 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Kelzan XCD 
                 0.75 
                 kg/m 3   
               
               
                   
                 (polysaccharide gum) 
               
               
                   
                 Staflo R 
                 2 
                 kg/m 3   
               
               
                   
                 (sodium carboxymethyl 
               
               
                   
                 cellulose) 
               
               
                   
                 Starpak DP 
                 6 
                 kg/m 3   
               
               
                   
                 (modified starch) 
               
               
                   
                 Calcarb 325 
                 10 
                 kg/m 3   
               
               
                   
                 (calcium carbonate) 
               
               
                   
                 Calcarb 0 
                 10 
                 kg/m 3   
               
               
                   
                 (calcium carbonate) 
               
             
          
           
               
                   
                 Caustic Soda 
                 pH 10 
               
             
          
           
               
                   
                 Q&#39;Clean ™ 
                 5% 
                 v/v 
               
               
                   
                 (mixture of petroleum 
               
               
                   
                 hydrocarbons) 
               
               
                   
                   
               
             
          
         
       
     
     Data illustrating the effectiveness will be presented herein after. 
     Contaminants testing on the drilling fluid showed minimal effects on its rheology and cleaning ability. Thus, gypsum and salt (NaCl) produced a moderate decrease in fluid rheology. The cleaning ability was affected only by salt; slightly reduced from 96% wt. to 80% wt. Solids contamination was simulated by adding 6% v/v tar sand to the drilling fluid already containing 5% v/v tar sand. The fluid behaved very well, cleaning 26% wt. tar sand off of the extra 6% v/v tar sand added. 
     After finding the fluid formulation and testing the contaminants, the environmental aspect of fluid development was reviewed. At the end of the well, the drilling fluid is a direct emulsion that contains as the internal phase (oil phase) the solvent (Q&#39;Clean™) and the dissolved tar. In order to be able to dispose of the drilling fluid, the emulsion has to be broken and oil phase has to be separated and removed. 
     Breaking the emulsion of PolyTar™ System was attempted in three ways:
         1. By making use of chemical demulsifiers. Eight demulsifiers were tested with no good results;   2. Making use of non-emulsifiers (two products) in the mud formulation to prevent the forming of a stable emulsion; and   3. Using a polymer breaker (four products, enzymes and bleach) to reduce the fluid viscosity and speed up the oil separation.       

     Q&#39;Break™ (citric acid and amylase) (enzyme) at concentration of 2 kg/m 3  is the best product to help with emulsion breaking and oil separation from the drilling fluid. It produces a fast reduction in mud viscosity, the emulsion breaks easily and the oil (Q&#39;Clean™+Tar) separates on top of fluid. After the treatment with Q&#39;Break™ 2 kg/m 3  and 24 hours static at 22° C., the oil left in emulsion in the mud was only 0.47% v/v. Most of the oil phase (Q&#39;Clean™ and dissolved Tar) was separated from the mud as a top layer and could be skimmed off. 
     Q&#39;Break™ is an enzyme that works well at low temperatures, however, higher concentrations are recommended. Also, the product is safe and environmentally friendly. 
     A new approach to tar sand drilling resulted in development of a new drilling fluid addressing specific problems encountered in SAGD drilling projects. 
     The new drilling fluid was designed to solve the problem of tar sand stickiness by removing the tar from the sand. Lower toxicity and lower cost were pursued as attributes of the new drilling fluid designed. 
     Tables 1 and 2 set forth data and observations noted. 
     In respect of the drilling fluid composition, the following procedure was observed.
         Various additives at various concentrations were added to water to examine the capacity to remove tar and clean the sand.   200 ml of the testing fluid received 20 g of tar sands.   The mixture was mixed on a Barnant mixer for 30 minutes at room temperature. The range of temperature for the testing was between 5° C. and 30° C.       

     Table 1 tabulates the data and observations noted 
     
       
         
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
             
             
               
                 Fluid Additive selection 
               
             
          
           
               
                 Additive &amp; concentration 
                   
                   
               
               
                 in water 
                 WTS, g 
                 Visual observations 
               
               
                   
               
               
                 Blank (water) 
                 19.580 
                 Tar sands appeared unchanged. Fluid phase is clear and clean. 
               
               
                 PAW 2315 @ 1% v/v 
                 19.660 
                 Tar sands appeared unchanged. Fluid phase is clear. 
               
               
                 PAW 2315 @ 3% v/v 
                 20.125 
                 There is a very small amount of clean sand. The tar sand left is broken into smaller pieces; 
               
               
                   
                   
                 however, they remained hard. Fluid phase contains suspended small oil drops cleaned off 
               
               
                   
                   
                 the sand. 
               
               
                 PAW 3900 @ 1% v/v 
                 20.138 
                 Similar to PAW 2315 @ 1% v/v. 
               
               
                 PAW 3900 @ 3% v/v 
                 20.632 
                 There is a very small amount of clean sand. The tar sand left seems to remain in same size 
               
               
                   
                   
                 pieces; however, they remained hard. Fluid phase contains suspended small oil drops 
               
               
                   
                   
                 cleaned off the sand. 
               
               
                 WAW 3917 @ 3% v/v 
                 19.883 
                 Similar to PAW 2315 @ 1% v/v. 
               
               
                 WAO 3919U @ 3% v/v 
                 20.281 
                 Works well. Most sand is loose and fairly clean and the fluid phase is dark coloured. There 
               
               
                   
                   
                 are a few small soft pieces of tar sand left on the bottom of the beaker. 
               
               
                 WAO 3919U @ 1% v/v 
                 20.002 
                 Similar to PAW 3919U @ 3% v/v. Just not quite as effective in cleaning the sand. 
               
               
                 Beta Cyclod. @ 5 kg/m 3   
                 20.420 
                 There is a very small amount of clean sand. The tar sand left seems to remain in same size 
               
               
                   
                   
                 pieces. Fluid phase has a thin oily film on top. There are lost of small tar sand particles. 
               
               
                 Beta Cyclod. @ 10 kg/m 3   
                 21.940 
                 No significant improvement. 
               
               
                 Beta Cyclod. @ 20 kg/m 3   
                 20.600 
                 No significant improvement. Noticeable is the fact that 20 kg/m 3  appears to be above its 
               
               
                   
                   
                 solubility. 
               
               
                 Cut Clean @ 1% v/v 
                 20.283 
                 There is a large amount of clean sand and large pieces of tar sand left. The fluid phase is 
               
               
                   
                   
                 clear with no suspended solids. It has an oily film and a ring at the surface. 
               
               
                 Cut Clean @ 2% v/v 
                 20.146 
                 The tar sand is completely broken down. On top of the sand layer there is a layer of large oil 
               
               
                   
                   
                 globules separated when agitation ceased. The fluid phase is cloudy, tan, with the odd 
               
               
                   
                   
                 suspended globule of oil and a thick layer of oil on top. 
               
               
                 Cut Clean @ 3% v/v 
                 19.948 
                 The sand is completely entrapped in what appears to be a water in oil emulsion on the 
               
               
                   
                   
                 bottom of the beaker. This very viscous layer with a gel like consistency is easily moved 
               
               
                   
                   
                 with agitation. The fluid phase is similar to the one above. 
               
               
                 Mudd Lite @ 2% v/v 
                 20.885 
                 Tar sands appeared unchanged. Fluid phase is tan in colour and has a layer of foam on top. 
               
               
                 Mudd Lite @ 6% v/v 
                 19.962 
                 Similar to Mudd Lite @ 2% v/v. 
               
               
                 DH6-115-2 
                 19.802 
                 Tar sands appeared unchanged. Fluid phase is clear. 
               
               
                 E X107 @ 3% v/v 
                 20.800 
                 Tar sands appeared unchanged. Fluid phase is clear. 
               
               
                 E X1501 @ 3% v/v 
                 20.670 
                 There is a very small amount of clean sand. The tar sand left seems to remain in same size 
               
               
                   
                   
                 pieces. In water, this additive coagulated in a cream-yellow layer that separates on top of the 
               
               
                   
                   
                 fluid phase when at rest. 
               
               
                 E XA923 @ 3% v/v 
                 20.791 
                 Tar sands appeared unchanged. Fluid phase is clear. 
               
               
                 E X1033 @ 3% v/v 
                 19.703 
                 It broke the large tar sand pieces into small ones but there is no clean sand. 
               
               
                 S DN82 @ 3% v/v 
                 20.799 
                 The sand is completely entrapped in what appears to be a water in oil emulsion on the 
               
               
                   
                   
                 bottom of the beaker. The liquid phase above this bottom layer is clean and clear. 
               
               
                 E X1557 @ 3% v/v 
                 19.600 
                  ~75% of tar sand is completely clean. The rest of tar sand is in pieces looking unchanged. 
               
               
                   
                   
                 Under the microscope can see the oil in water emulsion that has a dark colour. There is a 
               
               
                   
                   
                 thin film of oil on top of fluid phase. 
               
               
                 E X1557 @ 1% v/v 
                 20.557 
                 Similar to above test, just that on the sand grains are not quite as clean. 
               
               
                 E X1557@ 5% v/v 
                   
                 Same as @ 3% v/v. 
               
               
                 E X 606 @ 3% v/v 
                 20.903 
                 There is a very small amount of clean sand. The tar sand left seems to remain in same size 
               
               
                   
                   
                 pieces. The fluid phase is light tan in colour and contains few tar particles suspended. 
               
               
                 E X 109 @ 3% v/v 
                 19.282 
                  ~75% of tar sand is completely clean. The rest of tar sand is in pieces looking unchanged. 
               
               
                   
                   
                 Under the microscope can see the fluid as oil in water emulsion that has a dark colour. 
               
               
                   
                   
                 There is a thin film of oil on top of fluid phase. 
               
               
                 E X 109 @ 5% v/v 
                 20.104 
                 Same as @ 3% v/v. 
               
               
                 S DN71 @ 3% v/v 
                 20.120 
                  ~50% of sand is partially clean and the other 50% is left unchanged in tar sand pieces. The 
               
               
                   
                   
                 fluid phase is oil in water emulsion. 
               
               
                 S DN120 @ 3% v/v 
                 20.322 
                 There is less than 1% of clean sand. The tar sand left seems to remain in same size pieces. 
               
               
                   
                   
                 The fluid phase is clean and clear. 
               
               
                 S DN114 @ 3% v/v 
                 19.820 
                 As above 
               
               
                 S DN121 @ 3% v/v 
                 20.026 
                 ~15-20% of sand is clean. The rest appears unchanged. The fluid phase is milky-gray in 
               
               
                   
                   
                 colour. 
               
               
                 S DN87 @ 3% v/v 
                 20.735 
                  ~75% of sand is completely clean. The rest of tar sand is in fairly small pieces. Under the 
               
               
                   
                   
                 microscope can see the fluid as oil in water emulsion that has a dark colour. 
               
               
                 S DN87 @ 3% v/v 
                 20.610 
                 Some improvement from 3% v/v, however, there still are a few tar sand pieces left. 
               
               
                 S DN76 @ 3% v/v 
                 21.028 
                 Most of tar sand (~75%) is a flowing sludge on the bottom of beaker. There are a few pieces 
               
               
                   
                   
                 of tar sand 
               
               
                 DT78 @ 3% v/v 
                 20.782 
                 ~80-90% of sand is fairly clean but the oil is not emulsioned and just lays and sticks to the 
               
               
                   
                   
                 sand layer. 
               
               
                 DG56 @ 3% v/v 
                 20.980 
                 There is less than 1% of clean sand. The tar sand left seems to remain in same size pieces. 
               
               
                   
                   
                 The fluid phase is clean and clear. 
               
               
                 M38 @ 3% v/v 
                 20.853 
                  ~50% of sand is fairly clean and the other 50% is left small tar sand pieces. The fluid phase 
               
               
                   
                   
                 is oil in water emulsion. 
               
               
                 M150 @ 3% v/v 
                 19.320 
                  ~50% of loose sand, dark, still coated with oil. The rest of tar sand seems to remain in same 
               
               
                   
                   
                 size pieces. The fluid phase is dark 
               
               
                 M192 @ 3% v/v 
                 20.962 
                  ~75% of tar sand is completely clean. The rest of tar sand is in pieces looking unchanged. 
               
               
                   
                   
                 Under the microscope can see the oil in water emulsion that has a dark colour. There is a thin 
               
               
                   
                   
                 film of oil on top. 
               
               
                 M192 @ 5% v/v 
                 20.042 
                 Some improvement from 3% v/v, however there still are a few tar sand pieces left. 
               
               
                 M187 @ 3% v/v 
                 20.178 
                 ~15-20% of sand is clean. The rest appears unchanged. The fluid phase is tan in colour. 
               
               
                 Solvent @ 5% v/v 
                 19.314 
                  ~80% of sand is loose, free flowing but still covered by oil material 
               
               
                 P2-181-9 @ 1% v/v 
                 20.386 
                  ~50% of sand is fairly clean and the other 50% is left small tar sand pieces. The fluid phase 
               
               
                   
                   
                 is an emulsion. 
               
               
                 P2-181-11B @ 1% v/v 
                 20.408 
                 ~15-20% of sand is clean. The rest appears unchanged. 
               
               
                 P2-181-15B @ 1% v/v 
                 20.560 
                  ~50% of sand is fairly clean and the other 50% is left small tar sand pieces. The fluid phase 
               
               
                   
                   
                 is an emulsion. 
               
               
                 P2-181-19B @ 1% v/v 
                 21.300 
                 Complete balling of tar sands that became soft (it incorporated water) and sticky. 
               
               
                 P2-181-16B @ 1% v/v 
                 21.107 
                 ~15-20% of sand is clean. The rest appears unchanged. 
               
               
                 P2-181-21B @ 1% v/v 
                 20.144 
                 ~15-20% of sand is clean. The rest of tar sand is soft and sticky. 
               
               
                 Travis 2095 @ 1% v/v 
                 21.893 
                  ~5% of sand is clean. The rest appears unchanged. 
               
               
                 Travis 2704 @ 1% v/v 
                 20.982 
                 Tar sands appeared unchanged. Fluid phase is clear. 
               
               
                   
               
             
          
           
               
                 Drilling Fluid selection - Polymer/Stable K system 
               
             
          
           
               
                 Additive &amp; concentration 
                   
                   
               
               
                 In drilling fluid 
                 WTS, g 
                 Visual Observations 
               
               
                   
               
               
                 Blank (Poly./Stable K) 
               
               
                 E XZ1557 @ 1% v/v 
                 20.634 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 E XZ1557 @ 3% v/v 
                 20.049 
                  ~40% of tar sand remained on the 30 mesh screen as small and large pieces. Dark fluid 
               
               
                   
                   
                 phase of oil in water emulsion. 
               
               
                 Xylene/Isopropanol 
                 20.250 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 @ 3% v/v 
               
               
                 Diesel @ 3% v/v 
                 20.975 
                 There is a small amount of loose sand. Tar sand left remained in same size pieces. Fluid 
               
               
                   
                   
                 phase is emulsion with suspended tar particles. 
               
               
                 Diesel @ 10% v/v 
                 19.580 
                 Most solids are loose, still covered by oil and flowing. 
               
               
                 Diesel @ 10% v/v + XZ1557 
                 20.078 
                 Tar sands appeared unchanged. The oil is emulsioned as extremely small drops that could 
               
               
                 @ 3% v/v 
                   
                 not contact the tar sands and is fairly clean. 
               
               
                 BDD100 @ 3% v/v 
                 20.980 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 BDS300 @ 3% v/v 
                 19.047 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 BDS200 @ 3% v/v 
                 20.382 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 E X1577 @ 3% v/v 
                 20.490 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 E X1421 @ 3% v/v 
                 20.195 
                 It produced rapid precipitation-coagulation of the Polymer/Stable K system. 
               
               
                 E X1262 @ 3% v/v 
                 20.728 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 E X1667 @ 3% v/v 
                 20.801 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 DWB-1-5 @ 3% v/v 
                 20.221 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 DWB-1-9 @ 3% v/v 
                 20.453 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 DWB-1-6 @ 3% v/v 
                 20.735 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 DWB-1-7 @ 3% v/v 
                 20.466 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 DWB-1-8 @ 3% v/v 
                 19.952 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 Solvent @ 3% v/v + XZ1557 
                 20.942 
                 Some clean sand grains seen under microscope. Most tar sand is left uncleaned as small 
               
               
                 @ 1% v/v 
                   
                 pieces. 
               
               
                 Solvent @ 10% v/v 
                 20.631 
                 Cleaned most of sand. Mixture is poured on a 30 mesh screen. ~10% of tar sand remained 
               
               
                   
                   
                 on the screen. Can see the clear - clean sand grains suspended in the fluid and the dark oil 
               
               
                   
                   
                 drops. Fluid phase is very dark due to the dissolved oil. 
               
               
                 Solvent @ 10% v/v + Rev 
                 20.17 
                  &lt;5% of tar sand left on the 30 mesh screen as small and soft pieces. Dark fluid phase 
               
               
                 Dust 4% v/v 
                   
                 containing almost completely clean sand. 
               
               
                 Solvent @ 7% v/v + Rev 
                 20.353 
                  ~5-7% of tar sand left on the 30 mesh screen. The rest as above. 
               
               
                 Dust 4% v/v 
               
               
                 M192 @ 5% v/v 
                 20.824 
                  ~70% of tar sand remained on the 30 mesh screen as small and large pieces. Dark fluid 
               
               
                   
                   
                 phase. 
               
               
                 Amodrill 1400 @ 10% v/v 
                 20.560 
                  ~30% of tar sand remained on the 30 mesh screen as small and large pieces. Dark fluid 
               
               
                   
                   
                 phase. 
               
               
                 Emulam D30 @ 5% v/v 
                 20.106 
                 ~100% of tar sand remained on the 30 mesh screen as unchanged small and large pieces. 
               
               
                 Cut Clean @ 5% v/v 
                 20.929 
                  ~30% of tar sand remained on the 30 mesh screen as small and large pieces. Dark fluid 
               
               
                   
                   
                 phase. 
               
               
                   
               
             
          
           
               
                 Drilling Fluid selection - Gel Chem system 
               
             
          
           
               
                 Additive &amp; concentration 
                   
                   
               
               
                 in drilling fluid 
                 WTS, g 
                 Visual Observations 
               
               
                   
               
               
                 Blank (Gel Chem sys.) 
                 20.651 
                 Tar sands appeared unchanged. Fluid phase contains small tar particles suspended. 
               
               
                 Tar Solvent @ 10% v/v 
                 20.920 
                  ~20% of tar sand remained on the 30 mesh screen as small and large pieces. Dark fluid 
               
               
                   
                   
                 phase with fairly clean sand suspended. 
               
               
                 Tar Solvent @ 10% v/v + Rev 
                 20.700 
                 As above. 
               
               
                 Dust @ 4% v/v 
               
               
                   
               
               
                 Additive concentration and 
               
               
                 mixture temperature 
                 WTS, g 
                 Visual Observations 
               
               
                   
               
               
                 Tar Solvent @ 20% v/v- 
                 20.878 
                  ~10% of tar sand left on the 30 mesh screen as small and soft pieces. Dark fluid phase 
               
               
                 5° C. 
                   
                 containing almost completely sand. 
               
               
                 Tar Solvent @ 10% v/v- 
                 19.968 
                  ~50% of tar sand left on the 30 mesh screen as small and soft pieces. Dark fluid phase. 
               
               
                 10° C. 
               
               
                 Tar Solvent @ 15% v/v- 
                 20.261 
                  ~20% of tar sand left on the 30 mesh screen as small and soft pieces. Dark fluid phase. 
               
               
                 10° C. 
               
               
                 Tar Solvent @ 20% v/v- 
                 20.325 
                  ~10% of tar sand left on the 30 mesh screen as small and soft pieces. Dark fluid phase 
               
               
                 10° C. 
                   
                 containing almost completely sand. 
               
               
                 Tar Solvent @ 15% v/v- 
                 20.380 
                  ~20% of tar sand left on the 30 mesh screen as small and soft pieces. Dark fluid phase. 
               
               
                 15° C. 
               
               
                 Tar Solvent @ 20% v/v- 
                 20.375 
                  ~10% of tar sand left on the 30 mesh screen as small and soft pieces. Dark fluid phase 
               
               
                 15° C. 
                   
                 containing almost completely sand. 
               
               
                 Tar Solvent @ 10% v/v- 
                 20.713 
                  ~5% of tar sand left on the 30 mesh screen as small and soft pieces. Dark fluid phase 
               
               
                 20° C. 
                   
                 containing almost completely sand. 
               
               
                 Tar Solvent @ 10% v/v- 
                 20.532 
                 As above 
               
               
                 25° C. 
               
               
                 Tar Solvent @ 10% v/v- 
                 20.342 
                  ~3% of tar sand left on the 30 mesh screen as small and soft pieces. Dark fluid phase 
               
               
                 30° C. 
                   
                 containing almost completely sand. 
               
               
                   
               
             
          
         
       
     
     In connection with the fluid testing, the following procedure was involved.
         200 mL of drilling fluid, discussed herein previously, was placed in a beaker to which 20 g of Tar Sands was added. This was mixed on a Barnant mixer for 30 minutes at room temperature. The mixture was passed through a 30 mesh screen.       

     The test was repeated in a temperature range of between 5 and 30° C. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Tar sands from 397.4 m depth - Drilling fluid testing 
               
             
          
           
               
                 Solvent concentration in 
                   
                   
               
               
                 drilling fluid 
               
               
                 and test temperature 
                 WTS, g 
                 Visual Observations 
               
               
                   
               
               
                 15% v/v Solvent &amp; 5° C. 
                 20.450 
                 ~15-20% of tar sand left on the 30 mesh screen (small and large pieces) 
               
               
                   
                   
                 and a significant amount of clean large sand grains (~3 mm diameter). 
               
               
                   
                   
                 Dark fluid phase containing completely clean sand 
               
               
                 20% v/v Solvent &amp; 5° C. 
                 19.781 
                 ~10% of tar sand left on the 30 mesh screen (small and large pieces) and 
               
               
                   
                   
                 a significant amount of clean large sand grains (~3 mm diameter). Dark 
               
               
                   
                   
                 fluid phase containing completely clean sand 
               
               
                 10% v/v Solvent &amp; 10° C. 
                 19.968 
                 ~20% of tar sand left on the 30 mesh screen as various size pieces. The 
               
               
                   
                   
                 rest is as above. 
               
               
                 15% v/v Solvent &amp; 10° C. 
                 20.261 
                 ~15% of tar sand left on the 30 mesh screen as various size pieces. The 
               
               
                   
                   
                 rest is as above. 
               
               
                 20% v/v Solvent &amp; 10° C. 
                 20.371 
                  ~7-10% of tar sand left on the 30 mesh screen as small and soft pieces. 
               
               
                   
                   
                 The rest is as above. 
               
               
                 10% v/v Solvent &amp; 15° C. 
                 20.482 
                 ~15% of tar sand left on the 30 mesh screen as various size pieces. The 
               
               
                   
                   
                 rest is as above. 
               
               
                 15% v/v Solvent &amp; 15° C. 
                 20.037 
                 ~15% of tar sand left on the 30 mesh screen as various size pieces. The 
               
               
                   
                   
                 rest is as above. 
               
               
                 20% v/v Solvent &amp; 20° C. 
                 20.389 
                  ~3% of tar sand left on the 30 mesh screen as small size pieces. The rest 
               
               
                   
                   
                 is as above. 
               
               
                  0% v/v Solvent &amp; 20° C. 
                 20.253 
                 ~80% of tar sand left on the 30 mesh screen as small size pieces. The 
               
               
                   
                   
                 solids that passed through the screen are suspended in the fluid and 
               
               
                   
                   
                 consist of tar sands and heavy oil particles. 
               
               
                 10% v/v Solvent &amp; 20° C. 
                 20.135 
                  ~7-10% of tar sand left on the 30 mesh screen (small and large pieces) 
               
               
                   
                   
                 and a significant amount of clean large sand grains (~3 mm diameter). 
               
               
                   
                   
                 Dark fluid phase containing completely clean sand 
               
               
                 10% v/v Solvent &amp; 25° C. 
                 20.185 
                  ~5% of tar sand left on the 30 mesh screen as various size pieces. The 
               
               
                   
                   
                 rest is as above. 
               
               
                 10% v/v Solvent &amp; 30° C. 
                 20.019 
                 No tar sand left on the 30 mesh screen. The only solids left on screen are 
               
               
                   
                   
                 the clean large sand grains (~3 mm diameter). Dark fluid phase containing 
               
               
                   
                   
                 completely clean sand. 
               
               
                   
               
               
                 Note: 
               
               
                 WTS—weight of tar sands. 
               
             
          
         
       
     
     In all the above tests where the new drilling fluid was used (all except sample with 0% v/v Solvent), the fluid phase was an oil in water emulsion. The oil drops had a good size (not too small, not too big) and were dark colored due to the tar having been stripped off the sand. 
     The core sample of tar sands used to perform the above testing showed very small pieces of completely clean solids (shale like). These clean solids were avoided when tar sand samples were removed from the core during testing. 
     Tables 3 through 22 tabulate data for different polymer systems together with specific listing for each. 
     As set forth herein previously, having listed the necessary components for the polymer system, ranges for effectiveness were required for determination. The following two polymer systems were tested 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 Polymer System A 
                   
                 Polymer System B 
                   
               
             
          
           
               
                 Additive 
                 Concentration 
                 Additive 
                 Concentration 
               
               
                   
               
               
                 Kelzan 
                 1.5 kg/m 3   
                 Kelzan 
                 2 kg/m 3   
               
               
                 XCD ® 
                   
                 XCD ® 
               
               
                 Staflo ® R 
                  2 kg/m 3   
                 Staflo ® R 
                 2 kg/m 3   
               
               
                 Starpak ® 
                  6 kg/m 3   
                 Starpak ® 
                 6 kg/m 3   
               
               
                 DP 
                   
                 DP 
               
               
                 Calcarb 
                 10 kg/m 3   
                 Calcarb 
                 10 kg/m 3   
               
               
                 325 
                   
                 325 
               
               
                 Calcarb 0 
                 10 kg/m 3   
                 Calcarb 0 
                 10 kg/m 3   
               
               
                 Caustic 
                 pH 10 
                 Caustic 
                 pH 10 
               
               
                 Soda 
                   
                 Soda 
               
               
                   
               
               
                 Q/C = Q&#39;Clean 
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Mud Formulation Testing - Rheology and API fluid loss at 23° C. 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 Gels, 
                 PV, 
                 YP, 
                 FL, 
               
               
                 Formulation 
                 600 rpm 
                 300 rpm 
                 200 rpm 
                 100 rpm 
                 60 rpm 
                 30 rpm 
                 6 rpm 
                 3 rpm 
                 Pa 
                 cP 
                 Pa 
                 mL 
               
               
                   
               
               
                 A 
                  65 
                 47 
                 40 
                 30 
                 23 
                 17 
                  8 
                  7 
                 3.5/4.0 
                 18 
                 14.5 
                 13.8 
               
               
                 A + 2.5% Q&#39;C 
                  66 
                 49 
                 41 
                 30 
                 24 
                 18 
                  8 
                  7 
                 3.5/4.0 
                 18 
                 16.0 
                 12.0 
               
               
                 A + 5% Q&#39;C 
                  70 
                 52 
                 43 
                 32 
                 25 
                 18 
                  9 
                  8 
                 4.0/4.5 
                 18 
                 17.0 
                  9.8 
               
               
                 A + 10% Q&#39;C 
                  71 
                 52 
                 43 
                 32 
                 25 
                 19 
                  9 
                  8 
                 4.5/4.5 
                 19 
                 16.5 
                  8.3 
               
               
                 B 
                 101 
                 78 
                 67 
                 48 
                 40 
                 30 
                 12 
                 10 
                 4.5/5.0 
                 23 
                 27.5 
                 11.2 
               
               
                 B + 2.5% Q&#39;C 
                 105 
                 81 
                 69 
                 52 
                 41 
                 30 
                 13 
                 11 
                 5.0/5.5 
                 24 
                 28.5 
                 11.0 
               
               
                 B + 5% Q&#39;C 
                 110 
                 84 
                 72 
                 54 
                 43 
                 31 
                 14 
                 11 
                 5.5/5.5 
                 26 
                 29.0 
                 12.4 
               
               
                 B + 10% Q&#39;C 
                 115 
                 89 
                 75 
                 57 
                 46 
                 33 
                 15 
                 12 
                 6.0/6.0 
                 26 
                 31.5 
                  9.0 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Tar Sand Cleaning at 23° C. 
               
             
          
           
               
                   
                 Weight, g 
                 Tar sand 
               
             
          
           
               
                 Fluid 
                 Tar 
                   
                 Residue 
                 Residue 
                 cleaned, 
               
               
                 Formulation 
                 sand 
                 Dish 
                 &amp; Dish 
                 &gt;30 mesh 
                 % wt. 
               
               
                   
               
             
          
           
               
                 A 
                 27.131 
                 1.060 
                 23.013 
                 21.953 
                 19.1 
               
               
                 A + 2.5% Q&#39;C 
                 27.122 
                 1.000 
                 7.890 
                 6.890 
                 74.6 
               
               
                 A + 5% Q&#39;C 
                 27.300 
                 1.033 
                 2.112 
                 1.079 
                 96.0 
               
               
                 A + 10% Q&#39;C 
                 27.644 
                 1.004 
                 1.671 
                 0.667 
                 97.6 
               
               
                 B 
                 27.233 
                 1.039 
                 23.474 
                 22.435 
                 17.6 
               
               
                 B + 2.5% Q&#39;C 
                 27.473 
                 1.038 
                 8.375 
                 7.337 
                 73.3 
               
               
                 B + 5% Q&#39;C 
                 27.457 
                 1.031 
                 2.718 
                 1.687 
                 93.9 
               
               
                 B + 10% Q&#39;C 
                 27.295 
                 1.038 
                 2.273 
                 1.235 
                 95.5 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Contaminants Testing on the PolyTar System (PTS = A + 5% Q&#39;C). 
               
               
                 Rheology at 23° C. 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 Gels, 
                 PV, 
                 YP, 
               
               
                 Sample 
                 600 rpm 
                 300 rpm 
                 200 rpm 
                 100 rpm 
                 60 rpm 
                 30 rpm 
                 6 rpm 
                 3 rpm 
                 Pa 
                 cP 
                 Pa 
               
               
                   
               
             
          
           
               
                 PTS 
                 64 
                 47 
                 39 
                 28 
                 23 
                 16 
                 8 
                 6 
                 3.0/3.5 
                 17 
                 15 
               
               
                 PTS + 5 kg/m 3   
                 48 
                 35 
                 29 
                 20 
                 16 
                 12 
                 5 
                 4 
                 2.5/2.5 
                 13 
                 11 
               
               
                 Gypsum 
               
               
                 PTS + 1 kg/m 3  Lime 
                 64 
                 47 
                 39 
                 28 
                 23 
                 16 
                 8 
                 6 
                 3.0/3.5 
                 17 
                 15 
               
               
                 PTS + NaOH for pH12 
                 62 
                 46 
                 38 
                 28 
                 22 
                 15 
                 7 
                 5 
                 3.0/3.0 
                 16 
                 15 
               
               
                 PTS + 5 kg/m 3  NaCl 
                 56 
                 41 
                 34 
                 24 
                 19 
                 13 
                 6 
                 5 
                 2.5/3.0 
                 15 
                 13 
               
               
                 PTS + 10 kg/m 3  NaCl 
                 54 
                 39 
                 32 
                 23 
                 18 
                 13 
                 6 
                 5 
                 2.5/3.0 
                 15 
                 12 
               
               
                 PTS + 20 kg/m 3  NaCl 
                 49 
                 35 
                 29 
                 21 
                 16 
                 11 
                 5 
                 4 
                 2.0/2.5 
                 14 
                 10.5 
               
               
                 PTS + 6% vol. Tar 
                 72 
                 52 
                 42 
                 31 
                 24 
                 18 
                 9 
                 6 
                 3.0/3.5 
                 20 
                 16 
               
               
                 Sand 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Contaminants Testing on the PolyTar System 
               
               
                 (PTS). API fluid loss 
               
             
          
           
               
                   
                   
                 FL, 
               
               
                   
                 Sample 
                 mL 
               
               
                   
                   
               
             
          
           
               
                   
                 PTS 
                 10 
               
               
                   
                 PTS + 5 kg/m 3  Gypsum 
                 9.5 
               
               
                   
                 PTS + 1 kg/m 3  Lime 
                 10 
               
               
                   
                 PTS + 5 kg/m 3  NaCl 
                 9.5 
               
               
                   
                 PTS + 10 kg/m 3  NaCl 
                 9 
               
               
                   
                 PTS + 20 kg/m 3  NaCl 
                 8 
               
               
                   
                 PTS + 6% vol. Tar Sand 
                 6 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Tar Sand Cleaning in contaminated fluid at 
               
               
                 23° C. - 5% vol. Tar Sand in the Fluid Sample 
               
             
          
           
               
                   
                   
                 Tar 
               
               
                   
                 Weight, g 
                 sand 
               
             
          
           
               
                   
                 Tar 
                   
                 Residue 
                 Residue 
                 cleaned, 
               
               
                 Fluid Sample 
                 sand 
                 Dish 
                 &amp; Dish 
                 &gt;30 mesh 
                 % wt. 
               
               
                   
               
             
          
           
               
                 PolyTar System (PTS) 
                 27.300 
                 1.033 
                 2.112 
                 1.079 
                 96.0 
               
               
                 PTS + 5 kg/m 3  Gypsum 
                 27.611 
                 1.002 
                 2.882 
                 1.880 
                 93.2 
               
               
                 PTS + 1 kg/m 3  Lime 
                 27.273 
                 1.027 
                 2.527 
                 1.500 
                 94.5 
               
               
                 PTS + 5 kg/m 3  NaCl 
                 27.458 
                 0.998 
                 5.720 
                 4.722 
                 82.8 
               
               
                 PTS + 10 kg/m 3  NaCl 
                 27.397 
                 1.004 
                 6.278 
                 5.274 
                 80.7 
               
               
                 PTS + 20 kg/m 3  NaCl 
                 27.315 
                 1.004 
                 6.425 
                 5.421 
                 80.2 
               
               
                 PTS + 6% vol. Tar Sand 
                 27.289 
                 1.020 
                 21.099 
                 20.079 
                 26.4 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 PolyTar System/Dissolved Tar Emulsion Breaking at 
               
               
                 23° C. - Removal of dissolved tar. 
               
             
          
           
               
                   
                 Conc., 
                   
               
               
                 Demulsifier 
                 L/m 3   
                 Notes on emulsion behaviour 
               
               
                   
               
             
          
           
               
                 None 
                   
                 Oil drops are small but visible with naked eye. The oil in water emulsion is stable. it does not 
               
               
                   
                   
                 break in over 8 hours. After 24 hours there is a very small amount of free oil on top of fluid. 
               
               
                 T2001 
                 1 
                 Oil drops are not visible with naked eye. Under the microscope they look 2-3 times smaller than 
               
               
                   
                 2 
                 they were initially. The oil in water emulsion became more stable. It does not break in over 24 
               
               
                   
                   
                 hours. There is no free oil on top of fluid. 
               
               
                 T2005 
                 1 
                 Oil drops are not visible with naked eye. Under the microscope they look 2-3 times smaller than 
               
               
                   
                 2 
                 they were initially. The oil in water emulsion became more stable. It does not break in over 24 
               
               
                   
                   
                 hours. There is no free oil on top of fluid. 
               
               
                 T2007 
                 1 
                 Oil drops are not visible with naked eye. Under the microscope they look 2-3 times smaller than 
               
               
                   
                 2 
                 they were initially. The oil in water emulsion became more stable. It does not break in over 24 
               
               
                   
                   
                 hours. There is no free oil on top of fluid. 
               
               
                 T2508 
                 1 
                 Oil drops are not visible with naked eye. Under the microscope they look 2-3 times smaller than 
               
               
                   
                 2 
                 they were initially. The oil in water emulsion became more stable. It does not break in over 24 
               
               
                   
                   
                 hours. There is no free oil on top of fluid. 
               
               
                 NE 125 
                 0.5 
                 Oil drops are small but visible with naked eye. The oil in water emulsion is stable. It does not 
               
               
                   
                 1 
                 break in over 8 hours. After 24 hours there is a very small amount of free oil on top of fluid. 
               
               
                   
                 2 
               
               
                 NE 723 
                 0.5 
                 Oil drops are small but visible with naked eye. The oil in water emulsion is stable. It does not 
               
               
                   
                 1 
                 break in over 8 hours. After 24 hours there is a very small amount of free oil on top of fluid. 
               
               
                   
                 2 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 9 
               
             
             
               
                   
               
               
                 PolyTar System/Dissolved Tar Emulsion - Preventing forming 
               
               
                 a stable emulsion using non-emulsifiers (23° C.). 
               
             
          
           
               
                   
                 Conc., 
                   
               
               
                 Non-emulsifier 
                 L/m 3   
                 Notes on emulsion behaviour 
               
               
                   
               
               
                 None 
                   
                 Oil drops are small but visible with naked eye. The oil in water emulsion is stable. It does not 
               
               
                   
                   
                 break in over 8 hours. After 24 hours there is a very small amount of free oil on top of fluid. 
               
               
                 NE 125 
                 1 
                 Oil drops are not visible with naked eye. Under the microscope they look 2-3 times smaller than 
               
               
                   
                 2 
                 they were initially. The oil in water emulsion became more stable. It does not break in over 24 
               
               
                   
                   
                 hours. There is no free oil on top of fluid. 
               
               
                 NE 723 
                 1 
                 Oil drops are not visible with naked eye. Under the microscope they look 2-3 times smaller than 
               
               
                   
                 2 
                 they were initially. The oil in water emulsion became more stable. It does not break in over 24 
               
               
                   
                   
                 hours. There is no free oil on top of fluid. 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 10 
               
             
             
               
                   
               
               
                 Tar Sand Cleaning at 23° C. - PTS cleaning ability 
               
               
                 when using non-emulsifiers at 1 L/m 3 . 
               
             
          
           
               
                   
                 Weight, g 
                 Tar sand 
               
             
          
           
               
                   
                 Tar 
                   
                 Residue 
                 Residue 
                 cleaned, 
               
               
                 Non-emulsifier 
                 sand 
                 Dish 
                 &amp; Dish 
                 &gt;30 mesh 
                 % wt. 
               
               
                   
               
             
          
           
               
                 NE 125 
                 27.655 
                 1.036 
                 13.601 
                 12.565 
                 54.6 
               
               
                 NE 723 
                 27.504 
                 1.000 
                 8.898 
                 8.898 
                 67.6 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 Viscosifier selection to prevent forming a stable PolyTar System/ 
               
               
                 Dissolved Tar Emulsion - Polymer (Viscosifier) 
               
               
                 Testing in PolyTar System - Rheology at 23° C. 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 Gels, 
                 PV, 
                 YP, 
               
               
                 Viscosifier 
                 kg/m 3   
                 600 rpm 
                 300 rpm 
                 200 rpm 
                 100 rpm 
                 60 rpm 
                 30 rpm 
                 6 rpm 
                 3 rpm 
                 Pa 
                 cP 
                 Pa 
               
               
                   
               
             
          
           
               
                 Kelzan XCD 
                 1.5 
                 70 
                 52 
                 43 
                 32 
                 25 
                 18 
                 9 
                 8 
                   4/4.5 
                 18 
                 17 
               
               
                 Biovis 
                 1.5 
                 54 
                 37 
                 29 
                 18 
                 13 
                  8 
                 3 
                 2 
                   1/1.5 
                 27 
                 5 
               
               
                 Biovis 
                 3 
                 73 
                 53 
                 44 
                 33 
                 27 
                 20 
                 10  
                 8 
                 4.5/6.5 
                 20 
                 16.5 
               
               
                 Geovis XT 
                 1.5 
                 71 
                 51 
                 42 
                 32 
                 25 
                 19 
                 10  
                 9 
                 5/7 
                 20 
                 15.5 
               
               
                 HEC 
                 1.5 
                 92 
                 70 
                 58 
                 43 
                 33 
                 23 
                 9 
                 7 
                 3.5/3.5 
                 22 
                 24 
               
               
                 Xanvis 
                 1.5 
                 60 
                 43 
                 36 
                 26 
                 20 
                 15 
                 7 
                 6 
                   3/3.5 
                 17 
                 13 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 12 
               
             
             
               
                   
               
               
                 Tar Sand Cleaning at 23° C. - PTS cleaning ability 
               
               
                 when using viscosifiers and concentrations above mentioned. 
               
             
          
           
               
                   
                 Weight, g 
                 Tar sand 
               
             
          
           
               
                   
                 Tar 
                   
                 Residue 
                 Residue 
                 cleaned, 
               
               
                 Viscosifier 
                 sand 
                 Dish 
                 &amp; Dish 
                 &gt;30 mesh 
                 % wt. 
               
               
                   
               
             
          
           
               
                 Kelzan XCD 
                 27.300 
                 1.033 
                 2.112 
                 1.079 
                 96.0 
               
               
                 Biovis - 1.5 
                 27.345 
                 1.009 
                 5.076 
                 4.067 
                 85.1 
               
               
                 Biovis - 3 
                 27.474 
                 1.033 
                 3.398 
                 2.365 
                 91.4 
               
               
                 Geovis XT 
                 27.343 
                 1.020 
                 4.354 
                 3.334 
                 87.8 
               
               
                 HEC 
                 27.456 
                 1.031 
                 9.140 
                 8.109 
                 70.5 
               
               
                 Xanvis 
                 27.333 
                 1.002 
                 4.638 
                 3.636 
                 86.7 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 13 
               
             
             
               
                   
               
               
                 Viscosifier selection to prevent forming a 
               
               
                 stable PolyTar System/Dissolved Tar 
               
               
                 Emulsion - Testing at 23° C. 
               
             
          
           
               
                   
                 Conc., 
                   
               
               
                 Viscosifier 
                 kg/m 3   
                 Notes on emulsion behaviour within 6 hours 
               
               
                   
               
             
          
           
               
                 Kelzan XCD 
                 1.5 
                 The oil in water emulsion is less stable. 
               
               
                   
                   
                 Emulsion is slowly breaking. There is a bit 
               
               
                   
                   
                 of free oil on top of fluid after 6 hours. This 
               
               
                   
                   
                 sample looks the best. 
               
               
                 Biovis 
                 3 
                 The oil in water emulsion is stable. No sign of 
               
               
                   
                   
                 emulsion breaking in 6 hours. 
               
               
                   
                   
                 There is no free oil on top of fluid. 
               
               
                 Geovis XT 
                 1.5 
                 The oil in water emulsion is stable. No sign of 
               
               
                   
                   
                 emulsion breaking in 6 hours. 
               
               
                   
                   
                 There is no free oil on top of fluid. 
               
               
                 HEC 
                 1.5 
                 The oil in water emulsion is stable. No sign of 
               
               
                   
                   
                 emulsion breaking in 6 hours. 
               
               
                   
                   
                 There is no free oil on top of fluid. 
               
               
                 Xanvis 
                 1.5 
                 The oil in water emulsion appears less stable. 
               
               
                   
                   
                 Emulsion is slowly breaking. There are traces 
               
               
                   
                   
                 of free oil on top of fluid after 6 hours. 
               
               
                   
                   
                 This sample is the next best. 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 14 
               
             
             
               
                   
               
               
                 Polymer Breaker Testing on PTS containing Kelzan 
               
               
                 XCD @ 1.5 kg/m 3  - Rheology 
               
               
                 after 24 hours @ 23 ° C. 
               
             
          
           
               
                 Breaker &amp; conc., 
                   
                   
                   
                   
                   
                   
                   
                   
                 Gels, 
                 PV, 
                 YP, 
               
               
                 kg/m 3   
                 600 rpm 
                 300 rpm 
                 200 rpm 
                 100 rpm 
                 60 rpm 
                 30 rpm 
                 6 rpm 
                 3 rpm 
                 Pa 
                 cP 
                 Pa 
               
               
                   
               
             
          
           
               
                 None 
                 66 
                 48 
                 41 
                 30 
                 24 
                 17 
                 8 
                 6 
                   3/3.5 
                 18 
                 15 
               
               
                 Q&#39;Break, 2 
                 41 
                 28 
                 22 
                 15 
                 11 
                  8 
                 4 
                 3 
                 1.5/1.5 
                 13 
                 7.5 
               
               
                 Chembreak HC, 3 
                 41 
                 27 
                 22 
                 15 
                 11 
                  8 
                 3 
                 2 
                   1/1.5 
                 14 
                 6.5 
               
               
                 Chembreak EBS, 3 
                 52 
                 38 
                 31 
                 22 
                 17 
                 12 
                 6 
                 5 
                 2.5/3   
                 14 
                 12 
               
               
                 Chembreak EBS, 3* 
                 48 
                 34 
                 28 
                 20 
                 16 
                 11 
                 5 
                 4 
                 2/2 
                 14 
                 10 
               
               
                 Bleach, 5 L/m 3   
                 26 
                 17 
                 13 
                  9 
                  7 
                  5 
                 2 
                 2 
                 1/1 
                  9 
                 4 
               
               
                   
               
               
                 Note: 
               
               
                 *sample contains 5,000 ppm Cl as NaCl. 
               
             
          
         
       
     
     An adjusted polymer system was then reviewed. 
     
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 Adjusted PolyTar System formulation (less viscosifier) 
               
             
          
           
               
                 Additive 
                 Concentration 
                 Additive 
                 Concentration 
               
               
                   
               
               
                 Kelzan 
                 .75 kg/m 3   
                 Xanvis ® 
                 1 kg/m 3   
               
               
                 XCD ® 
               
               
                 Staflo ® R 
                  2 kg/m 3   
                 Staflo ® R 
                 2 kg/m 3   
               
               
                 Starpak ® 
                  6 kg/m 3   
                 Starpak ® 
                 6 kg/m 3   
               
               
                 DP 
                   
                 DP 
               
               
                 Calcarb 
                 10 kg/m 3   
                 Calcarb 
                 10 kg/m 3   
               
               
                 325 
                   
                 325 
               
               
                 Calcarb 0 
                 10 kg/m 3   
                 Calcarb 0 
                 10 kg/m 3   
               
               
                 Caustic 
                 pH 10 
                 Caustic 
                 pH 10 
               
               
                 Soda 
                   
                 Soda 
               
               
                 Q&#39; Clean 
                 5% vol. 
                 Q&#39; Clean 
                 5% vol. 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 15 
               
             
             
               
                   
               
               
                 PolyTar System/Dissolved Tar Emulsion (5% vol. Tar Sand 
               
               
                 in the mud) - Rheology at 23° C. 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 Gels, 
                 PV, 
                 YP, 
               
               
                 Viscosifier 
                 kg/m 3   
                 600 rpm 
                 300 rpm 
                 200 rpm 
                 100 rpm 
                 60 rpm 
                 30 rpm 
                 6 rpm 
                 3 rpm 
                 Pa 
                 cP 
                 Pa 
               
               
                   
               
             
          
           
               
                 Kelzan XCD 
                 0.75 
                 58 
                 42 
                 34 
                 24 
                 18 
                 12 
                 5 
                 4 
                 2/2 
                 16 
                 13 
               
               
                 Xanvis 
                 1 
                 62 
                 46 
                 38 
                 27 
                 21 
                 15 
                 6 
                 5 
                 2.5/3   
                 16 
                 15 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 16 
               
             
             
               
                   
               
               
                 Tar Sand Cleaning at 23° C. - PTS cleaning ability when 
               
               
                 using viscosifiers and concentrations above mentioned. 
               
             
          
           
               
                   
                 Weight, g 
                 Tar sand 
               
             
          
           
               
                   
                 Tar 
                   
                 Residue 
                 Residue 
                 cleaned, 
               
               
                 Viscosifier 
                 sand 
                 Dish 
                 &amp; Dish 
                 &gt;30 mesh 
                 % wt. 
               
               
                   
               
               
                 Kelzan XCD 
                 27.397 
                 1.059 
                 4.116 
                 3.057 
                 88.8 
               
               
                 Xanvis 
                 27.512 
                 1.040 
                 5.076 
                 4.378 
                 84.1 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 17 
               
             
             
               
                   
               
               
                 Polymer Breaker Testing on PTS containing Kelzan 
               
               
                 XCD @ 0.75 kg/m 3  - Rheology 
               
               
                 after 2 hours @ 23° C. 
               
             
          
           
               
                 Breaker &amp; conc., 
                   
                   
                   
                   
                   
                   
                   
                   
                 Gels, 
                 PV, 
                 YP, 
               
               
                 kg/m 3   
                 600 rpm 
                 300 rpm 
                 200 rpm 
                 100 rpm 
                 60 rpm 
                 30 rpm 
                 6 rpm 
                 3 rpm 
                 Pa 
                 cP 
                 Pa 
               
               
                   
               
             
          
           
               
                 None 
                 58 
                 42 
                 34 
                 24 
                 18  
                 12  
                 5 
                 4 
                 2/2 
                 16 
                 13 
               
               
                 Q&#39;Break, 2 
                 41 
                 25 
                 19 
                 12 
                 9 
                 5 
                 2 
                 2 
                 1/1 
                 16 
                 4.5 
               
               
                 Chembreak HC, 3 
                 27 
                 17 
                 13 
                  8 
                 5 
                 4 
                 1 
                 1 
                 0.5/0.5 
                 10 
                 3.5 
               
               
                 Bleach, 5 L/m 3   
                 56 
                 36 
                 27 
                 17 
                 13  
                 8 
                 3 
                 2 
                 1/1 
                 20 
                 8 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 18 
               
             
             
               
                   
               
               
                 Polymer Breaker Testing on PTS containing 
               
               
                 Xanvis @ 1 kg/m 3  - Rheology 
               
               
                 after 2 hours @ 23° C. 
               
             
          
           
               
                 Breaker &amp; conc., 
                   
                   
                   
                   
                   
                   
                   
                   
                 Gels, 
                 PV, 
                 YP, 
               
               
                 kg/m 3   
                 600 rpm 
                 300 rpm 
                 200 rpm 
                 100 rpm 
                 60 rpm 
                 30 rpm 
                 6 rpm 
                 3 rpm 
                 Pa 
                 cP 
                 Pa 
               
               
                   
               
             
          
           
               
                 None 
                 62 
                 46 
                 38 
                 27 
                 21 
                 15 
                 6 
                 5 
                 2.5/3   
                 16 
                 15 
               
               
                 Q&#39;Break, 2 
                 44 
                 28 
                 22 
                 14 
                 10 
                  7 
                 3 
                 2 
                 1/1 
                 16 
                 6 
               
               
                 Chembreak HC, 3 
                 41 
                 28 
                 22 
                 15 
                 11 
                  7 
                 3 
                 2 
                 1/1 
                 13 
                 7.5 
               
               
                 Bleach, 5 L/m 3   
                 69 
                 47 
                 38 
                 25 
                 19 
                 13 
                 5 
                 4 
                   2/2.5 
                 22 
                 12.5 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 19 
               
             
             
               
                   
               
               
                 Retort Test on PolyTar System/Dissolved Tar 
               
               
                 Emulsion (5% vol. Tar Sand in the mud) 
               
             
          
           
               
                 Sample from 
                   
                   
               
               
                 ½ height of emulsion 
                   
                 Total 
               
               
                 in 250 mL graduated 
                 Retort content, % v/v 
                 Hydrocarbons Content 
               
             
          
           
               
                 cylinder after 24 hours 
                 Oil 
                 Water 
                 Solids 
                 (Core Labs), % v/v 
               
               
                   
               
               
                 Blank (no ECA) 
                 5 
                 94 
                 1 
                   
               
               
                 Q&#39;Break 2 kg/m3 
                 2 
                 97 
                 1 
                 0.473 
               
               
                 Q&#39;Break 4 kg/m3 
                 1 
                 99 
                 0 
                 0.492 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 20 
               
             
             
               
                   
               
               
                 Q&#39;Break Testing at 23° C. (room) on PTS containing Kelzan 
               
               
                 XCD @ 0.75 kg/m3 - Rheology @ 23° C. 
               
             
          
           
               
                 Q&#39;Break 
                   
                   
                   
                   
                   
                   
                   
                   
                 Gels, 
                 PV, 
                 YP, 
               
               
                 kg/m 3   
                 600 rpm 
                 300 rpm 
                 200 rpm 
                 100 rpm 
                 60 rpm 
                 30 rpm 
                 6 rpm 
                 3 rpm 
                 Pa 
                 cP 
                 Pa 
               
               
                   
               
             
          
           
               
                 None 
                 58 
                 42 
                 34 
                 24 
                 18  
                 12  
                 5 
                 4 
                 2/2 
                 16 
                 13 
               
               
                 2 kg/m 3 , after 2 hours 
                 40 
                 26 
                 20 
                 13 
                 9 
                 6 
                 2 
                 2 
                 1/1 
                 14 
                 6 
               
               
                 2 kg/m 3 , after 6 hours 
                 36 
                 23 
                 18 
                 11 
                 8 
                 5 
                 2 
                 1 
                 0.5/0.5 
                 13 
                 5 
               
               
                 2 kg/m 3 , after 24 hours 
                 31 
                 20 
                 15 
                 10 
                 7 
                 4 
                 1 
                 1 
                 0.5/0.5 
                 11 
                 4.5 
               
               
                 4 kg/m 3 , after 2 hours 
                 39 
                 25 
                 20 
                 13 
                 9 
                 6 
                 2 
                 2 
                 1/1 
                 14 
                 5.5 
               
               
                 4 kg/m 3 , after 6 hours 
                 25 
                 16 
                 12 
                  7 
                 5 
                 3 
                 1 
                 1 
                 0.5/0.5 
                  9 
                 3.5 
               
               
                 4 kg/m 3 , after 24 hours 
                 20 
                 12 
                  9 
                  6 
                 4 
                 3 
                 1 
                 1 
                 0.5/0.5 
                  8 
                 2 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 21 
               
             
             
               
                   
               
               
                 Q&#39;Break Testing at 3° C. (fridge) on PTS containing Kelzan 
               
               
                 XCD @ 0.75 kg/m3 - Rheology @ 3° C. 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 Gels, 
                 PV, 
                 YP, 
               
               
                 Q&#39;Break, kg/m 3   
                 600 rpm 
                 300 rpm 
                 200 rpm 
                 100 rpm 
                 60 rpm 
                 30 rpm 
                 6 rpm 
                 3 rpm 
                 Pa 
                 cP 
                 Pa 
               
               
                   
               
             
          
           
               
                 None 
                 74 
                 52 
                 43 
                 30 
                 23 
                 16  
                 7 
                 5 
                 2.5/3   
                 22 
                 15 
               
               
                 2 kg/m 3 , after 3 hours 
                 54 
                 35 
                 27 
                 17 
                 12 
                 8 
                 3 
                 2 
                 1/1 
                 19 
                 8 
               
               
                 2 kg/m 3 , after 6 hours 
                 40 
                 25 
                 19 
                 12 
                  9 
                 5 
                 2 
                 1 
                 0.5/0.5 
                 15 
                 5 
               
               
                 4 kg/m 3 , after 2 hours 
                 47 
                 31 
                 23 
                 15 
                 11 
                 7 
                 2 
                 2 
                 1/1 
                 16 
                 7.5 
               
               
                 4 kg/m 3 , after 6 hours 
                 38 
                 24 
                 17 
                 11 
                  8 
                 5 
                 2 
                 1 
                 0.5/0.5 
                 14 
                 5 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 22 
               
             
             
               
                   
               
               
                 Emulsion Breaking using both Q&#39;Break 2 kg/m3, let sit 
               
               
                 3 hours then add demulsifier. Testing at 23° C. 
               
             
          
           
               
                   
                 Conc., 
                   
               
               
                 Demulsifier 
                 L/m 3   
                 Notes on emulsion behaviour - 250 mL sample in a graduated glass cylinder. 
               
               
                   
               
               
                 None 
                   
                 Emulsion is slowly breaking. There is a a layer of ~12 mL of very dark fluid on top after 3 hours. 
               
               
                 (Blank) 
                   
                 Large oil drops form and accumulate towards top of fluid. 
               
               
                   
                   
                 After 48 hours the sample shows a very good oil separation. After 1 week there is the oil layer on 
               
               
                   
                   
                 top, clear water phase in the middle and solids layer on bottom. 
               
               
                 RD2069 
                 1 
                 Uppon mixing the RD2069 demulsifier, there was a stringy, gummy precipitate formed. Otherwise, 
               
               
                   
                   
                 the sample looks similar to the blank but having smaller oil drops accumulating towards the top. 
               
               
                   
                   
                 Demulsifier cannot be used due to chemical incompatibility with mud components (precipitation). 
               
               
                 T2005 
                 1 
                 Emulsion seems to very slowly break. There is a a layer of ~9 mL of very dark fluid on top with a 
               
               
                   
                   
                 definite separation from the lighter layer beneath after 3 hours. However, the rest of the fluid 
               
               
                   
                   
                 shows no sign of forming visible oil drops. 
               
               
                   
                   
                 After 48 hours the sample shows the least oil separation of all. After 1 week the is a layer of oil 
               
               
                   
                   
                 separated but the rest of the fluid is muddy and seems to contain traces of oil. 
               
               
                 JC91-6B 
                 1 
                 Emulsion is slowly breaking. There is a a layer of ~12 mL of very dark fluid on top after 3 hours. 
               
               
                   
                   
                 Large oil drops form and accumulate towards top of fluid. 
               
               
                   
                   
                 After 48 hours the sample shows a very good oil separation same as the blank. 
               
               
                   
                   
                 After 1 week there is the oil layer, clear water phase and solids layer similar to the blank. 
               
               
                   
               
             
          
         
       
     
     Overall the polymer system containing the Kelzan XCD® in a concentration of 0.75 kg/m 3  provided preferred rheology, fluid loss and cleansing of tar sands. 
     FIELD EXAMPLE 
     In January/February of 2004, six wells were drilled which used the PolyTar drilling fluid system in part of the drilling operation. The wells, located in 84-11 W4 in Alberta Canada, were horizontal in nature with the intermediate and main horizontal tar sands drilled with Polytar. The nature of sand was one of ˜23 v/v % bitumen contained within a ˜3 milliDarcy permeable poorly consolidated matrix. 
     Typical drilling conditions with Polytar are ˜400 meters of drilled 311 mm intermediate hole with casing set at 90° inclination from vertical. The 222 mm horizontal section was ˜600 meters in length. The following table highlights some of the Polytar drilling parameters as compared to other water-based muds used in the same 84-11 W4 area. 
     
       
         
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 23 
               
             
             
               
                   
               
               
                 Drilling Fluid Performance of Bitumen Laden Sands 
               
             
          
           
               
                   
                 # of 
                 Average m 
                 Average 
                 Average 
                 Typical shaker 
               
               
                 System (year) 
                 wells 
                 drilled 
                 days to TD 
                 mud cost 
                 screen design 
               
               
                   
               
               
                 K 2 SO 4  polymer 
                 4 
                 1077 
                 4.8 
                 $27,755 
                  38 * 38 * 38 
               
               
                 (1998) 
               
               
                 K 2 SO 4  polymer 
                 6 
                 1357 
                 4.6 
                 $10,280 
                  38 * 38 * 38 
               
               
                 (1998) 
               
               
                 KCl polymer 
                 4 
                 1505 
                 8.8 
                 $43,907 
                  84 * 50 * 38 * 20 
               
               
                 (2003) 
                   
                   
                   
                   
                 140 * 110 * 84 * 50 
               
               
                 Polytar 
                 6 
                 1078 
                 3.9 
                 $22,531 
                 210 * 175 * 175 * 145 
               
               
                 (2004) 
                   
                   
                   
                   
                 210 * 210 * 180 * 145 
               
               
                   
               
             
          
         
       
     
     The data shows that the Polytar system has been cost effective. Days to total depth were similar to the 6 well project using K 2 SO 4  polymer and faster than the KCl polymer and K 2 SO 4  polymer (4 wells) groupings. Drilling fluid costs for the Polytar system were also very competitive. 
     The average shaker screen sizes used on the Polytar system were much finer than those used on the other three system groupings. The potassium based systems, which used the larger screen sizes, were designed to carry the insoluble bitumen to surface intact. Typical of these potassium systems however, the bitumen accretes onto metallic surfaces. The shaker screens become less effective when accretion occurs, thus the need for larger screen openings. 
     The Polytar system solubilizes at least part of the bitumen into the drilling fluid system, thus eliminating accretion and increasing the efficiency of the shaker screens. As a result, cleaning of the drilling fluid system of drilled sand is improved. The sand collected from the shaker screen from the bitumen laden drilled solids contained typically less than 0.5% v/v oil. 
     The Polytar wells at 84-11 W4 employed centrifuges for additional drilling fluids cleaning functions. In general, the sand coming from the centrifuge underflow was clean enough to meet mix-bury-cover regulations within Alberta. The following tables set out the analyses received from centrifuge underflows at 700 m and 800 m measured depths. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 24 
               
             
             
               
                   
               
               
                 Hydrocarbon content from Centrifuge Underflows with Polytar 
               
               
                 Subsoil Density = 1820 kg/m3; soil:waste mix ratio 3:1 
               
               
                 Waste Densities = 2020 and 1975 kg/m3 for 700 m and 800 m 
               
             
          
           
               
                   
                 700 m Analyses 
                 800 m Analyses 
                 Closure Criteria 
               
               
                   
               
             
          
           
               
                 Benzene 
                 0 
                 0 
                 0.073 
               
               
                 Toluene 
                 0 
                 0 
                 0.86 
               
               
                 Ethylbenzene 
                 0 
                 0 
                 0.19 
               
               
                 Xylenes 
                 0 
                 0 
                 25 
               
               
                 Fraction 1 
                 0 
                 0 
                 260 
               
               
                 Fraction 2 
                 170 
                 216 
                 900 
               
               
                 Fraction 3 
                 169 
                 212 
                 800 
               
               
                 Fraction 4 
                 68 
                 85 
                 5600 
               
               
                 Total HC&#39;s 
                 407 
                 513 
               
               
                   
               
             
          
         
       
     
     The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.