Abstract:
A method and product is disclosed which provides emulsion stability and filtration control to invert emulsion drilling fluids. The product comprises a blend of a carboxylic acid terminated polyamide and a mixture produced by the Diels-Alder reaction of dienophiles, preferably carboxylic acids, polycarboxylic acids, acid anhydrides, or combinations or mixes thereof, with a mixture of fatty acids and resin acids. The product is extremely effective, decreasing by about two-thirds the amount of emulsifier generally required to formulate an effective drilling fluid. The product also greatly reduces and in many cases eliminates the need for conventional fluid loss additives, and additionally provides electrical stability. Moreover, the product has a pour point as low as about 20 degrees Fahrenheit with minimal solvents, thereby eliminating the need to ship large amounts of inert material for use, and may be transported in a highly active state.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to methods for drilling boreholes in subterranean formations, particularly hydrocarbon bearing formations, and to drilling fluids for use in such drilling operations. More particularly, the present invention relates to oil or synthetic based drilling fluids, fluids comprising invert emulsions, and more particularly drilling fluid additives that facilitate or enhance emulsification, electrical stability or filtration properties of the drilling fluid.  
           [0003]    2. Description of Relevant Art  
           [0004]    A drilling fluid or mud is a specially designed fluid that is circulated through a wellbore as the wellbore is being drilled to facilitate the drilling operation. The various functions of a drilling fluid include removing drill cuttings from the wellbore, cooling and lubricating the drill bit, aiding in support of the drill pipe and drill bit, and providing a hydrostatic head to maintain the integrity of the wellbore walls and prevent well blowouts. Specific drilling fluid systems are selected to optimize a drilling operation in accordance with the characteristics of a particular geological formation.  
           [0005]    Oil or synthetic-based muds, or invert emulsions, are normally used to drill swelling or sloughing shales, salt, gypsum, anhydrite or other evaporite formations, hydrogen sulfide-containing formations, and hot (greater than about 300 degrees Fahrenheit) holes, but may be used in other holes penetrating a subterranean formation as well. These non-aqueous based drilling fluids typically contain oil or a synthetic oil or other synthetic material or synthetic fluid (“synthetic”) as the continuous phase and may also contain water which is dispersed in the continuous phase by emulsification so that there is no distinct layer of water in the fluid. The term “oil mud” or “oil or synthetic-based mud” typically means an invert oil mud emulsion or invert emulsion. An all oil mud simply comprises 100% oil by volume as the liquid phase; that is, there is no aqueous internal phase. An invert emulsion drilling fluid may commonly comprise between about 50:50 to 95:5 by volume oil phase to water phase.  
           [0006]    Most commonly, invert emulsions used in drilling typically comprise: abase oil or synthetic fluid for the external phase; a saline, aqueous solution for the internal phase (typically a solution comprising about 30% calcium chloride); and other agents or additives for suspension, fluid loss, density, oil-wetting, emulsification, filtration, and rheology control. With space at some well sites limited, such as on offshore platforms, and with increasing costs of transport of materials to a wellsite, there is industry-wide interest in, and on-going need for, more efficient and concentrated drilling fluid additives and for drilling fluids which can be formulated and maintained with minimal or fewer additives than common with prior art drilling fluids.  
         SUMMARY OF THE INVENTION  
         [0007]    An improved and more efficient material or product and method is disclosed for providing emulsion stability and filtration control to invert emulsions and other oil or synthetic based drilling fluids for use in drilling boreholes in subterranean formations, particularly hydrocarbon bearing formations.  
           [0008]    The product of the invention has the advantage of a pour point at temperatures as low as about 20 degrees Fahrenheit with minimal solvent. Thus, the product of the invention may be transported in a highly (about 90% to about 100%) active state, which reduces the need to inventory products containing different solvents for compatibility with the drilling fluid. This advantage further eliminates the need for shipping large amounts of inert material. Moreover, the product of the invention has the further advantage of providing high levels of filtration control to a drilling fluid made with conventional emulsifiers, especially at temperatures up to about 250° F. Still further, the product of this invention, when added to drilling fluids, reduces or eliminates the need for conventional fluid loss additives.  
           [0009]    The product of this invention comprises two primary components or parts. One part is a carboxylic acid-terminated polyamide and the other part is itself a mixture produced by the Diels-Alder reaction of dienophiles, preferably carboxylic acids, polycarboxylic acids, acid anhydrides, or combinations or mixes thereof, with a mixture of fatty acids and resin acids. These two components or parts are blended or mixed and further reacted with cations to form soaps. This saponification reaction may be achieved in the manufacturing process or it may be effected “in situ” by the presence of or addition of cations to the drilling fluid. As used herein, the term “in situ” shall be understood to mean in the drilling fluid. Typically, such saponification reaction will occur in the drilling fluid when the drilling fluid is being prepared for use as a drilling fluid or when the drilling fluid is in use as a drilling fluid in drilling a borehole in a subterranean formation. Drilling fluids commonly comprise cations. Sources of such cations include, without limitation, lime, quicklime, and calcium chloride, among others. Further, drilling fluids may incorporate cations contacted in or available from the subterranean formation itself. The method of the invention employs the product of the invention for improved drilling fluids and improved drilling of boreholes in subterranean formations. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a graph comparing the electrical stability of a synthetic based drilling fluid containing the product of the invention with the same synthetic based drilling fluid containing conventional emulsifiers instead of the product of the invention, using data from Tables 1 and 2.  
         [0011]    [0011]FIG. 2 is a graph comparing HTHP filtration of a synthetic based drilling fluid containing the product of the invention with the same synthetic based drilling fluid containing conventional emulsifiers instead of the product of the invention, using data from Tables 3 and 4. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0012]    The product of the invention comprises a blend, mixture, or a combination (hereinafter “blend) of a carboxylic acid-terminated polyamide (“Component ‘A’”) and a mixture (“Component ‘B’”) produced by the Diels-Alder reaction of dienophiles, preferably carboxylic acids, polycarboxylic acids, and anhydrides, or combinations or mixes thereof, with a mixture of fatty acids and resin acids. Component B has a ratio of fatty acids to resin acids preferably ranging from about 4:1 to about 1:1 and a most preferred ratio of about 2:1 and is preferably comprised of fatty acids and resin acids derived from the distillation of crude tall oil.  
         [0013]    Component A is preferably concentrated (i.e., about 90% active), and typically made from the condensation reaction between fatty acids and polyamines. The fatty acids and polyamines are reacted in such proportion as to create a “partial amide” intermediate product having a mole ratio of the reactive acid sites to amine sites ranges from about 0.5:1 to about 0.75:1 and most preferably about 0.6:1. This partial amide intermediate product is diluted with a minimum amount of solvent, as needed for further processing, and the remaining amine sites are further reacted with an acid anhydride or polycarboxylic acid to produce the carboxylic acid-terminated polyamide. A most preferred carboxylic acid-terminated fatty polyamide for use in the invention is EZ-MUL® NT CONCENTRATE, the active constituent of EZ-MUL® NT available from Halliburton Energy Services, Inc. in Houston, Tex., although other carboxylic acid terminated fatty polyamides are believed to be useable.  
         [0014]    In comprising the product of the invention, the preferred ratio of Component A to Component B is about 1:5 to about 1:1. Ratios of Component A to Component B of about 1:2 to about 1:3 are most preferred. The exact ratio of these two components or parts may vary greatly depending on the exact desired characteristics of the product. Preferably, however, the quantity of Component B will exceed the quantity of Component A.  
         [0015]    The blend comprising the product of the invention is preferably made by blending, mixing, or combining these two components—the polyamide and the modified fatty acid/resin acid mixture—together. After blending, the polyamide and fatty acid/resin acid components are reacted with cations to form soaps. Such reaction or saponification may be achieved as part of the manufacturing process of the product of the invention or may be effected in situ the drilling fluid by the presence or addition of cations to the drilling fluid. Calcium cations are preferred and may be obtained, for example, by reacting the polyamide and modified fatty acid/resin acid components with lime, quicklime, or calcium chloride.  
         [0016]    Tall oil is a commonly known product made from acid treatment of alkaline liquors obtained from the manufacture of wood pulp, and tall oil and its derivatives have previously been used in oil-well drilling muds. However, the modified fatty acid/resin acid component of the blend of the product of the invention alone is not effective for achieving the advantages of the invention. EZ-MUL® is known to have utility as an emulsifier for oil based drilling fluids. However, carboxylic acid-terminated fatty polyamides alone cannot achieve all of the advantages of the invention. In the combination disclosed, however, the blend (or mixture) comprising the product of the invention provides a marked advance in the art.  
         [0017]    The product of the invention is a powerfully efficient additive for oil or synthetic based drilling fluids, affording or effecting enhanced emulsification, and improved electrical stability and fluid loss control, with significantly less volume of additive than previously known or available with prior art drilling fluid additives. The product effects or helps facilitate emulsification typically in amounts of about one-third the quantity commonly needed for emulsification of oil or synthetic based fluids with prior art emulsifiers. That is, amounts of about three pounds to about five pounds of the product of the invention per barrel of drilling fluid can be effective for emulsification. Even lower quantities can improve the electrical stability and filtration control of drilling fluids, even if already emulsified with other emulsifiers.  
         [0018]    The product of the invention does not rely on a carrier. The material comprising the product is highly active and is believed to be useful with all or substantially all synthetic and oil-based systems known to be effective for drilling fluids. The product of the invention may also add viscosity to the drilling fluid and thus is preferably added to the base drilling fluid before any weighting agents such as barite, for example, are added.  
         [0019]    The product of this invention is stable even at temperatures up to (and including) about 250 degrees Fahrenheit without filtration additives and up to about 300 to about 350 degrees Fahrenheit with filtration additives. Adding wetting agents along with the product of the invention in an emulsifier package may improve the oil-wetting nature of the drilling fluid in some base oils but will not be needed in others. Wetting agents may also improve the rheological stability at temperatures up to about 300° F. The addition of wetting agents to drilling fluids comprising the product of the invention may also further enhance performance of some fluid systems.  
         [0020]    The product of the invention has a high acid value. Consequently, improved results may be seen when a neutralizer or neutralizing agent is added to the drilling fluid. For example, a mininum of about eight pounds of lime (or similar saponifying agent) might favorably be added per barrel of drilling fluid when about three pounds per barrel of the product of the invention are used in the drilling fluid. Additional lime (or similar saponifying agent) may be helpful or needed with larger quantities of product of the invention for optimum results, although satisfactory results might also be obtained with less.  
         [0021]    Care is recommended when using the product of this invention to avoid over-treating. Excess emulsifiers (i.e., more than needed to effect emulsification) in drilling fluids can contribute to high fluid viscosity at cold temperatures (i.e., temperatures less than about 45 degrees Fahrenheit). For deepwater operations (i.e., use of drilling fluids at depths of water greater than about 500 feet and at temperatures less than about 45 degrees Fahrenheit), wetting agents may preferably be added to help maintain low riser viscosities as drill solids are incorporated in or become carried by the drilling fluid.  
         [0022]    The method of the invention comprises adding the product of the invention to an oil or synthetic based drilling fluid or employing a drilling fluid comprising the product of the invention in drilling a borehole in a subterranean formation. In another embodiment, the method of the invention comprises adding the product of the invention to an oil or synthetic based drilling fluid to facilitate emulsification of the drilling fluid or the formation of invert emulsions.  
         [0023]    Experiments were conducted that demonstrate or exemplify the invention. Several formulations of synthetic or oil-based drilling fluids were prepared, typical of those used in the field, and all of which comprised invert emulsions. Specifically, samples of drilling fluids were prepared comprising a synthetic or diesel oil base, to which additives were added, including the product of the invention or a known emulsifier for comparison, as indicated in Tables 1-12 below. The different samples were subjected to different conditions, such as high temperatures or hot rolling, or further additives or contaminants, for example, simulated drill solids or salt water, for comparison of performance and properties. The results of tests tabulated in Tables 1-4 are graphed in FIGS. 1 and 2.  
         [0024]    As used in the tables, the following compounds or products have the meanings indicated below:  
         [0025]    SF BASE™ is a synthetic oil base for drilling fluids typically used in drilling mud systems such as PETROFREE®SF, available from Halliburton Energy Services, Inc. in Houston Tex.;  
         [0026]    LE BASE™ is a synthetic oil base for drilling fluids typically used in drilling mud systems such as PETROFREE® LE;  
         [0027]    GELTONE® II, is an organoclay for improving viscosity characteristics;  
         [0028]    SUSPENTONE® is an organoclay for improving the ability of a drilling fluid to suspend drill cuttings;  
         [0029]    INVERMUL® is an emulsifier;  
         [0030]    EZ MUL® is an emulsifier;  
         [0031]    LE SUPERMUL® is an emulsifier;  
         [0032]    LE MUL® is an emulsifier;  
         [0033]    DRILTREAT™ is a wetting agent;  
         [0034]    DEEP-TREAT™ is a wetting agent;  
         [0035]    BAROID® is barite, a weighting agent;  
         [0036]    DURATONE® HT is a filtration control agent; and  
         [0037]    BDF-258™ is the product of the invention.  
         [0038]    All trademarks are the property of Halliburton Energy Services, Inc. and the products are available from Halliburton Energy Services, Inc. in Houston, Tex.  
                                                                                                                                                                           TABLE 1                           PETROFREE ® SF       14 lb/gal; 75/25 OWR with 250,000 ppm WPS            Sample Mark   A (7.33 lb/bbl Active emulsifier content)                    SF BASE, bbl   0.516       Freshwater, bbl   0.181       GELTONE ® II, lb   3       SUSPENTONE ™, lb   1       LE ™ MUL, lb   4       LE ™ SUPERMUL, lb   6       Lime, lb   5       DURATONE ® HT, lb   7       BAROID ®, lb   330       Calcium chloride, lb   21.9       DEEP-TREAT ™, lb   3            Mixed 15 minutes at 7000 rpm on a Silverson L4RT before testing: mixed 10 minutes after rolling            Rev Dust, lb   —   45   —       15% NaCl Brine Added, % vol       —   33            Hot roiled @ 250° F., hr   —   16   16   16            Temperature, ° F.   120   40   120   40   120   40   120       Plastic viscosity, cP   23   80   24   112   37   108   38       Yield point, lb/100 ft 2     15   18   8   19   8   26   11       10 Sec gel, lb/100 ft 2     8   7   6   10   7   9   6       10 Min gel, lb/100 ft 2     9   11   8   18   10   12   10            Electrical stability, v   690   235    488   77       HTHP filtrate @ 250° F., ml   2.4      2.4   10.4   7.6 (0.5 water)       Fann 35 dial readings            600 rpm   61   178   56   243   82   242   87       300 rpm   38   98   32   131   45   134   49       200 rpm   29   69   24   91   33   94   36       100 rpm   20   38   15   51   20   53   23        6 rpm   7   7   5   10   5   10   7        3 rpm   6   6   4   9   4   8   6                                  
 
         [0039]    [0039]                                                                                                                                                                                                   TABLE 2                           PETROFREE ® SF       14 lb/gal; 75/25 OWR with 250,000 ppm WPS            Sample Mark   H3                    SF BASE, bbl   0.516       Freshwater, bbl   0.181       GELTONE ® II, lb   3       SUSPENTONE ™, lb   1       BDF-258, lb   3       Lime, lb   8       DURATONE ® HT, lb   7       BAROID ®, lb   330       Calcium chloride, lb   21.9       DEEP-TREAT ™, lb   3            Mixed 15 minutes at 7000 rpm on a Silverson L4RT before testing: mixed 10 minutes after rolling            Rev Dust, lb   —   45   —       15% NaCl Brine Added, % vol       —   33            Hot rolled @ 250° F., hr   —   —   16   16   16            Temperature, ° F.   120   40   120   40   120   40   120   40   120       Plastic viscosity, cP   29   78   27   72   26   N/A   49   113   43       Yield point, lb/100 ft 2     16   33   14   24   12   N/A   24   43   20       10 Sec gel, lb/100 ft 2     8   15   7   13   7   27   16   19   13       10 Min gel, lb/100 ft 2     10   17   9   15   9   57   36   20   13            Electrical stability, v   638   669   630   884   393       HTHP filtrate @ 250° F., ml       2.0   1.6   5.2   2.4       Fann 35 dial readings            600 rpm   74   189   68   168   64   O/S   122   269   106       300 rpm   45   111   41   96   38   186   73   156   63       200 rpm   35   82   32   72   30   139   56   116   48       100 rpm   24   53   22   45   20   88   38   72   32        6 rpm   9   17   8   14   8   29   15   21   12        3 rpm   8   15   7   12   7   26   14   19   11                                    
         [0040]    [0040]                                                                                                                                                                                                         TABLE 3                           PETROFREE ® LE       14 lb/gal; 75/25 OWR with 250,000 ppm WPS            Sample Mark   C                    LE BASE, bbl   0.5094       Freshwater, bbl   0.1793       GELTONE ® II, lb   3.5       SUSPENTQNE ™, lb   2       LE ™ MUL, lb   7       LE ™ SUPERMUL, lb   4       Lime, lb   7       DURATONE ® HT, lb   6       Calcium chloride, lb   21.8       BAROID ®, lb   332.3       DEEP-TREAT ™, lb   3.5            Mixed 15 minutes at 7000 rpm on a Silverson L4RT before testing; mixed 10 minutes after rolling            Rev Dust, lb   —   45   —       15% NaCl Brine Added. % vol       —   33            Hot rolled @ 250° F., hr   —   —   16   16   16            Temperature, ° F.   120   40   120   40   120   40   120   40   120       Plastic viscosity, cP   23   94   22   77   23   82   32   87   35       Yield point, lb/100 ft 2     12   51   9   18   6   12   5   14   4       10 sec gel, lb/100 ft 2     6   17   6   9   5   8   5   7   5       10 Min gel, lb/100 ft 2     9   21   8   15   7   15   8   10   6            Electrical stabilit , v   737   676   474   545   230       HTHP filtrate @ 250° F., ml       4.4   2.0   10.0   12.0-1.1 emul.            Fann 35 dial readings            600 rpm   58   239   53   172   52   176   69   188   74       300 rpm   35   145   31   95   29   94   37   101   39       200 rpm   26   108   24   67   22   66   28   70   29       100 rpm   17   66   16   38   13   37   17   38   17        6 rpm   6   19   5   9   4   8   4   7   5        3 rpm   5   17   4   8   3   7   3   6   4                                    
         [0041]    [0041]                                                                                                                                                                                                   TABLE 4                           PETROFREE ® LE       14 lb/gal; 75/25 OWR with 250,000 ppm WPS            Sample Mark   B2                    LE BASE, bbl   0.5163       Freshwater, bbl   0.1796       GELTONE ® II, lb   3       SUSPENTONE ™, lb   2       BDF-258, lb   3       Lime, lb   7       DURATONE ® HT, lb   6       Calcium chloride, lb   21.8       BAROID ®, lb   333.2       DEEP-TREAT ™, lb   33            Mixed 15 minutes at 7000 rpm on a Silverson L4RT before testing: mixed 10 minutes after rolling            Rev Dust, lb   —   45   —       15% NaCl Brine Added. % vol       —   33            Hot rolled @ 250° F., hr   —   —   16   16   16            Temperature, ° F.   120   40   120   40   120   40   120   40   120       Plastic viscosity, cP   26   72   23   64   23   98   34   96   36       Yield point, lb/100 ft 2     12   29   9   16   7   26   6   32   11       10 Sec gel. lb/100 ft 2     7   14   6   12   6   13   6   16   10       10 Min gel, lb/100 ft 2     9   18   8   16   9   28   8   21   9            Electrical stability, v   554   615   568   574   269       HTHP filtrate @ 250° F., ml       2.2   2.2   3.0   1.8       Fann 35 dial readings            600 rpm   64   173   55   144   53   222   74   224   83       300 rpm   38   101   32   80   30   124   40   128   47       200 rpm   29   75   25   58   23   89   29   94   36       100 rpm   20   47   17   35   15   52   18   58   23        6 rpm   7   15   6   10   6   13   4   16   8        3 rpm   6   14   5   9   5   11   3   14   7                                    
         [0042]    [0042]                                                                                                                                                                                                   TABLE 5                           PETROFREE ® SF       14 lb/gal; 75/25 OWR with 250,000 ppm WPS            Sample Mark   H2                    SF BASE, bbl   0.516       Freshwater, bbl   0.181       GELTONE ® II, lb   3       SUSPENTONE ™, lb   1       BDF-258, lb   3       Lime, lb   8       DURATONE ® HT, lb   7       BAROID ®, lb   330       Calcium chloride, lb   21.9       DEEP-TREAT ®, lb   3       DRILTREAT ®, lb   1            Mixed 15 minutes at 7000 rpm on a Silverson L4RT before testing; mixed 10 minutes after rolling            Rev Dust, lb   —   45   —       15% NaCl Brine Added, % vol       —   33            Hot rolled @ 250° F., hr   —   —   16   16   16            Temperature, ° F.   120   40   120   40   120   40   120   40   120       Plastic viscosity, cP   28   82   25   86   25   N/A   46   116   41       Yield point, lb/100 ft 2     14   36   16   29   14   N/A   22   45   22       10 Sec gel, lb/100 ft 2     7   17   7   14   8   28   18   19   12       10 Min gel, lb/100 ft 2     10   20   9   18   10   60   31   21   12            Electrical stability, v   603   694   684   846   409       HTHP filtrate @ 250° F., ml       1.2   1.6   4.0   1.6       Fann 35 dial readings            600 rpm   70   200   66   201   64   O/S   114   277   104       300 rpm   42   118   41   115   39   201   68   161   63       200 rpm   33   89   32   84   30   149   52   119   48       100 rpm   22   57   22   51   21    93   34   74   33        6 rpm   8   19   8   15   8    28   13   22   13        3 rpm   7   17   7   14   7    24   12   19   12                                    
         [0043]    [0043]                                                                                                                                                                                 TABLE 6                           PETROFREE ® SF       14 lb/gal; 75/25 OWR with 250,000 ppm WPS       NO DURATONE ® HT            Sample Mark   O                    SF BASE, lb   0.516       Freshwater, bbl   0.181       GELTONE ® II, lb   4       SUSPENTONE ™, lb   1       BDF-258, lb   3       Lime, lb   9       Calcium chloride, lb   21.9       BAROID ®, lb   330       DRILTREAT ®, lb   1       DEEP-TREAT ™, lb   3            Mixed 15 minutes at 7000 rpm on a Silverson L4RT before testing; mixed 10 minutes after roling            Hot rolled @ 250° F., hr   —   —   16   16   16       Rev Dust, lb   —   —   —   45   —       15% NaCl brine, % vol           —   —   33            Temperature, ° F.   120   40   120   40   120   40   120   40   120       Plastic viscosity, cP   28   88   33   85   29   N/A   50   N/A   69       Yield point, lb/100 ft 2     5   19   8   20   8   N/A   5   N/A   45       10 Sec gel, lb/100 ft 2     5   10   7   9   5    5   3   48   25       10 Min gel, lb/100 ft 2     8   14   9   13   7   14   10   &gt;60     62            Electrical stability @ 120° F., v   471   519   496/230   218   285       HTHP filtrate @ 250° F., ml       0.2   1.6   4.0   3.4-0.4 H 2 O       Fann 35 dial readings            600 rpm   61   195   74   190   66   O/S   105   O/S   183       300 rpm   33   107   41   105   37   173   55   O/S   114       200 rpm   25   75   31   75   27   123   39   256   87       100 rpm   16   43   20   44   17    68   21   163   57        6 rpm   5   10   7   10   5    7   3    45   26        3 rpm   4   8   6   8   4    5   2    40   24                                    
         [0044]    [0044]                                                                                                         TABLE 7                           INVERMUL ®       14 lb/gal; 250,000 WPS            Sample Mark   1   2   3   4   5                    Diesel, bbl   0.5395   0.5234   0.5679   0.5743   0.5608       Fresh water, bbl   0.1814   0.1815   0.1449   0.1453   0.1454       Oil-to-Water Ratio   75/25   75/25   80/20   80/20   80/20       GELTONE ® II, lb   2   2   2   2   2       SUSPENTONE ™, lb   1   1   —   —   —       BDF-258, lb   3.5   —   6   3   —       INVERMUL ® NT, lb   —   3   —   —   3       Lime, lb   8   8   12   8   8       DURATONE ® HT, lb   6   6   6   6   6       EZ MUL ® NT, lb   —   6   —   —   6       Calcium chloride, lb   22.0   22.1   17.6   17.7   17.7       BAROID ®, lb   302   301   307   310   309       Rev Dust, lb   20   20   20   20   20       DRILTREAT ®, lb   —   —   —   1.5   —            Hot rolled @ 300° F., hr   —   —   —   16   —   16   —   16       Plastic viscosity @ 150° F., cP   25   26   21   23   22   19   20   22       Yield point, lb/100 ft 2     31   53   17   11   13   9   30   8       10 Sec gel, lb/100 ft 2     26   32   12   14   8   8   16   8       10 Min gel, lb/100 ft 2     34   34   23   29   15   16   16   9       Electrical stability, v   593    1140   923   1302   697   783   1404   766       HTHP filtrate @ 300° F., ml     11.6*   3.8   6.2   16.4   5.6   10.0   5.4   7.6       Fann 35 dial readings       600 rpm   81   105   59   57   57   47   70   52       300 rpm   56   79   38   34   35   28   50   30       200 rpm   46   69   30   26   28   21   42   23       100 rpm   36   56   22   17   19   14   32   16        6 rpm   21   33   10   8   8   7   17   7        3 rpm   20   32   9   7   7   6   16   6                            
         [0045]    [0045]                                                                 TABLE 8                           INVERMUL ®       14 lb/gal; 80/20 OWR with 250,000 WPS            Sample Mark   10   11                    Diesel, bbl   0.577   0.577       Fresh water, bbl   0.145   0.145       GELTONE ® II, lb   6   6       BDF-258, lb   3   3       Lime. lb   8   8       Calcium chloride, lb   17.6   17.6       DEEP-TREAT ·, lb   1.5   1       BAROID ®, lb   312   312       Rev Dust, lb   20   20       DRILTREAT ®, lb   —   1            Hot rolled @ 150° F., hr   16   —   16   —       Hot rolled @ 250° F., hr   —   16   —   16       Plastic viscosity @ 150° F., cP   23   24   23   24       Yield point, lb/100 ft 2     28   10   25   12       10 Sec gel, lb/100 ft 2     17   10   18   11       10 Min gel, lb/100 ft 2     22   16   20   20       Electrical stability, v   686   783   561   723       HTHP filtrate @ 250° F., ml   5.6   6.8   6.6   9.4       HTHP filt.cake thickness, 1/32″   4   3   5   5       Fann 35 dial readings       600 rpm   74   58   71   60       300 rpm   51   34   48   36       200 rpm   42   26   39   28       100 rpm   32   17   30   19        6 rpm   17   7   17   8        3 rpm   16   6   17   8                            
         [0046]    [0046]                                                                                                                                                                                                   TABLE 9                           PETROFREE ® SF       14 lb/gal; 75/25 OWR with 250,000 ppm WPS       NO DURATONE ® HT            Sample Mark   I                    SF BASE, bbl   0.516       Freshwater, bbl   0.181       GELTONE ® II, lb   4       SUSPENTONE ™, lb   1       BDF-258, lb   3.5       Lime, lb   9       DURATONE ® HT, lb   —       Calcium chloride, lb   21.9       DEEP-TREAT ™, lb   3       BAROID ®, lb   330            Mixed 15 minutes at 7000 rpm on a Silverson L4RT before testing; mixed 10 minutes after rolling            Hot rolled @ 250° F., hr   —   —   16   16   16            Rev Dust, lb   —   45   —       15% NaCl Brine Added, % vol       —   33            Temperature, ° F.   120   40   120   40   120   40   120   58   120       Plastic viscosity, cP   29   85   32   76   31   N/A   54   N/A   71       Yield point, lb/100 ft 2     9   17   9   15    6   N/A   7   N/A   53       10 Sec gel, lb/100 ft 2     7   10   8   9   7   6   4   55   34       10 Min gel, lb/100 ft 2     8   15   11   10   7   13   8   —   65            Electrical stability, v   482   529   241   234   293       HTHP filtrate @ 250° F., ml       1.6      2.8*   6.0   5.0-1.0 H 2 O       Fann 35 dial readings            600 rpm   67   187   73   167   68   O/S   115   O/S   195       300 rpm   38   102   41   91   37   186   61   278   124       200 rpm   29   73   31   65   28   130   43   220   97       100 rpm   19   42   20   38   18    71   23   151   67        6 rpm   6   10   7   9   6    8   3    53   29        3 rpm   5   8   6   7   5    5   2    50   28                                            
         [0047]    [0047]                                                                                                                                                                                                   TABLE 10                           PETROFREE ® SF       14 lb/gal; 75/25 OWR with 250,000 ppm WPS       NO DURATONE ® HT            Sample Mark   N                    SF BASE, lb   0.516       Freshwater, bbl   0.181       GELTONE ® II, lb   4       SUSPENTONE ™, lb   1       BDF-258, lb   3.5       Lime, lb   9       Calcium chloride, lb   21.9       DEEP-TREAT ™, lb   4       BAROID ®, lb   330            Mixed 15 minutes at 7000 rpm on a Silverson L4RT before testing: mixed 10 minutes after rolling            Hot rolled @ 250° F., hrs   —   —   16   16   16            Rev Dust, lb   —   45   —       15% NaCl brine, % vol   —   —   33       DEEP-TREAT ™, lb   —    2    2            Temperature, ° F.   120   40   120   40   120   40   120   40   120       Plastic viscosity, cP   35   103   38   80   31   124   44   N/A   53       Yield point, lb/100 ft 2     11   18   11   16   6   22   5   N/A   10       10 Sec gel, lb/100 ft 2     8   10   7   8   6   5   5    8   6       10 Min gel, lb/100 ft 2     14   16   11   9   7   8   7   10   7            Electrical stability @ 120° F., v   503   527   209   275   156       HTHP filtrate @ 250° F., ml       0.6   1.2   1.6   1.0-trace emul       Fann 35 dial readings            600 rpm   81   224   87   176   68   270   93   O/S   116       300 rpm   46   121   49   96   37   146   49   189   63       200 rpm   35   85   37   68   29   101   35   134   44       100 rpm   22   49   24   39   18   55   20    74   25        6 rpm   7   10   7   8   6   6   4    10   5        3 rpm   6   8   6   7   5   4   3    7   4                                    
         [0048]    [0048]                                                                                                                                                                                 TABLE 11                           PETROFREE ® SF       14 lb/gal; 75/25 OWR with 250,000 ppm WPS            Sample Mark   BB                    SF BASE, lb   0.516       Freshwater, bbl   0.181       GELTONE ® II, lb   4       SUSPENTONE ™ , lb   1       BDF-258, lb   3.5       Lime, lb   9       Calcium chloride, lb   21.9       BD QUAT 2HT, lb   1       BAROID ® , lb   330       DEEP-TREAT ™ , lb   3            Mixed 15 minutes at 7000 rpm on a Silverson L4RT before testing: mixed 10 minutes after rolling            Hot rolled @ 250° F., hr   —   —   16   16   16       Rev Dust, lb   —   —   —   45   —       15% NaCl brine, % vol           —   —   25            Temperature, ° F.   120   40   120   40   120   40   120   40   120       Plastic viscosity, cP   29   76   30   75   28   119   40   119   43       Yield point, lb/100 ft 2     15   32   17   24   10   16   6   35   14       10 Sec gel, lb/100 ft 2     8   14   8   11   7   7   5   15   8       10 Min gel, lb/100 ft 2     13   17   9   12   8   11   10   15   9            Electrical stability @ 120° F., v   633   *486 average   333   576   223       HTHP filtrate @ 250° F., ml       2.2   5.4   4.0   3.0-0.2 emul.       Fann 35 dial readings            600 rpm   73   184   77   174   66   254   86   273   100       300 rpm   44   108   47   99   38   135   46   154   57       200 rpm   34   81   36   73   30   93   33   111   42       100 rpm   23   52   24   45   19   50   19   65   26        6 rpm   8   16   8   13   7   7   4   15   8        3 rpm   7   14   7   11   6   5   3   13   7                                            
         [0049]    [0049]                                                                                                                                                                                         TABLE 12                       14.0 lb/gal PETROFREE SF       70/30 OWR: 250.000 ppm WPS                                    Sample Mark   Base - D. Carbajal FLC Evaluation Data                            SF BASE, bbl   0.505           Freshwater, bbl   0.220           GELTONE ® II, lb   3           LE ™ MUL, lb   3           LE ™ SUPERMUL,   3           lb           Lime, lb   5           BAROID ® , lb   330           Calcium chloride, lb   27            A 3-gal. batch was mixed at low shear; then 30 min on a Silverson L4RT                BDF-258, lb   —   1.5   3                        Samples were mixed, then hot rolled 16 hours at 150° F.            Temperature, ° F.   40   120   40   120   40   120                    Plastic viscosity, cP   75   26   90   30   97   32       Yield point, lb/100ft 2     26   16   37   30   39   33       10 Sec gel, lb/100 ft 2     17   10   30   17   32   19       10 Min gel, lb/100 ft 2     18   12   30   20   33   24            Electrical stability, volts   259   650   679       HTHP filtrate @ 250° F.,   11.8   3.2   Trace       ml oil       HTHP filtrate @ 250° F.,   5.6   —   —       ml H 2 O            Fann 35 dial readings                               600 rpm   176   68   217   90   233   97       300 rpm   101   42   127   60   136   65       200 rpm   74   33   94   49   101   54       100 rpm   47   27   61   36   66   40        6 rpm   16   10   23   17   26   20        3 rpm   16   9   20   15   23   18                    
         [0050]    These experimental results show that the product of the invention has emulsion-forming capabilities comparable to or exceeding prior art emulsifiers at only about one-third the concentration and that the product of the invention improves the electrical stability of the drilling fluid, even after heat stress. These results also show that the product of the invention imparts very low filtration properties to the drilling fluids. Further, the product of the invention provides significantly better filtration control than conventional emulsifiers, especially when used with a wetting agent, even after solids and brine contamination. Still further, the tests showed that no fluid loss control additives were needed for the same filtration properties as prior art emulsifiers when the product of the invention was used. The tests also indicate that the product of the invention performs well with other emulsifying products, which should allow simpler maintenance treatments in oil or synthetic based fluids when using the product of the invention.  
         [0051]    In the method of the invention, the product of the invention is added to an oil or synthetic based drilling fluid or a drilling fluid comprising an invert emulsion to improve or facilitate the emulsification of the oil or synthetic base fluid.  
         [0052]    The foregoing description of the invention is intended to be a description of preferred embodiments. Various changes in the details of the described product and method can be made without departing from the intended scope of this invention as defined by the appended claims.