Abstract:
A well bore fluid recovery system and method is disclosed for recovering a column of well bore fluid within a stand of casing before cutting the casing. The recovery system relates to a system for preventing fluids from being spilled when casing is being finished for a well bore. After being run the casing must be cut and finished at an appropriate level to install rig equipment such as blow out preventers along with other equipment. However, because of earlier operations, the entire length of casing is typically filled with drilling fluid. Depending on conditions, the length of casing which is to be cut and removed may therefore over a 100-foot (27.4 meter) column of drilling fluid therein. The drilling fluid in this section must be properly drained before the casing is cut and removed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This is a continuation of U.S. Ser. No. 10/925,827, filed Aug. 25, 2004 now U.S. Pat. No. 7,134,502, which is incorporated herein by reference and priority to which is hereby claimed, which claimed priority to U.S. Provisional patent application No. 60/498,215 filed Aug. 27, 2003. 
   This is a continuation of U.S. Ser. No. 11/599,170, filed Nov. 14, 2006 now U.S. Pat. No. 7,373,987, which is incorporated herein by reference and priority to which is hereby claimed. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable 
   REFERENCE TO A “MICROFICHE APPENDIX” 
   Not applicable 
   BACKGROUND 
   The present invention relates generally to drilling fluid recovery and, more specifically, to a system for preventing fluids from being spilled when casing is being finished for a well bore. 
   The process of drilling subterranean wells to recover oil and gas from reservoirs, consists of boring a hole in the earth down to the petroleum accumulation in the reservoir, and installing pipe from the reservoir to the surface. Casing is a protective pipe liner within the well bore that is cemented in place to insure a pressure-tight connection to the oil and gas reservoir. The casing can be run from the rig floor as it is lowered into the well bore. 
   When running casing, drilling fluid is added to each section as it is run into the well. This procedure is necessary to prevent the casing from collapsing due to high pressures within the well bore. The drilling fluid acts as a lubricant which facilitates lowering the casing within the well bore. 
   Drilling fluid, or drilling mud, is very important to the rotary drilling process. Drilling and completion fluids which include fluids such as weighted mud, oil-based fluids, water-based muds and the like are often quite expensive and may frequently cost more than one million dollars per well. It is basically a mixture of water, clay, and special minerals and chemicals and performs many important functions. For example, drilling fluid exerts pressure inside the hole keeping fluids that may be in the formations from entering the hole and perhaps blowing out to the surface. In addition, pressure in the hole forces solid particles of clay in the mud to adhere to the sides of the hole as the drilling fluid circulates upward on its way to the surface. The solids form a thin, impermeable cake on the walls of the hole. If discharged drilling fluids can be hazardous to the environment. 
   The normal sequence for running casing involves suspending the casing from a top drive or non-top drive (conventional rotary rig) and lowering the casing into the well bore, filling each joint of casing with drilling fluid. The filling of each joint or stand of casing as it is run into the hole is the fill-up process. Lowering the casing into the well bore is facilitated by alternately engaging and disengaging elevator slips and spider slips with the casing string in a stepwise fashion, facilitating the connection of an additional stand of casing to the top of the casing string as it is run into the hole. 
   Circulation of the fluid is sometimes necessary if resistance is encountered as the casing is lowered into the well bore, preventing the running of the casing string into the hole. This resistance to running the casing into the hole may be due to such factors as drill cuttings, mud cake, or surface tension formed or trapped within the annulus between the well bore and the outside diameter of the casing, or caving of the well bore among other factors. In order to circulate the drilling fluid, the top of the casing must be sealed so that the casing may be pressurized with drilling fluid. Since the casing is under pressure the integrity of the seal is critical to safe operation, and to minimize the loss of expensive drilling fluid. Once the obstruction is removed the casing may be run into the hole as before. 
   Once the casing reaches the bottom, circulating of the drilling fluid is again necessary to test the surface piping system, to condition the drilling fluid in the hole, and to flush out wall cake and cuttings from the hole. Circulating is continued until at least an amount of drilling fluid equal to the volume of the inside diameter of the casing has been displaced from the casing and well bore. After the drilling fluid has been adequately circulated, the casing may be cemented in place. 
   After the casing has been run to the desired depth it may be cemented within the well bore. The purpose of cementing the casing is to seal the casing to the well bore formation. In order to cement the casing within the well bore, the assembly to fill and circulate drilling fluid is generally removed from the drilling rig and a cementing head apparatus installed. A special cementing head or plug container is installed on the top portion of the casing being held in place by the elevator. Since the casing and well bore are full of drilling fluid, it is first necessary to inject a spacer fluid to segregated the drilling fluid from the cement to follow. The cementing plugs are used to wipe the inside diameter of the casing and serves to separate the drilling fluid from the cement, as the cement is carried down the casing string. Once the calculated volume of cement required to fill the annulus has been pumped, the top plug is released from the cementing head. Drilling fluid or some other suitable fluid is then pumped in behind the top plug, thus transporting both plugs and the cement contained between the plugs to an apparatus at the bottom of the casing known as a float collar. Once the bottom plug seals the bottom of the casing, the pump pressure increases, which ruptures a diaphragm in the bottom of the plug. This allows the calculated amount of cement to flow from the inside diameter of the casing to a certain level within the annulus being cemented. The annulus is the space within the well bore between the ID of the well bore and the OD of the casing string. When the top plug comes in contact with the bottom plug, pump pressure increases, which indicates that the cementing process has been completed. Once the pressure is lowered inside the casing, a special float collar check valve closes, which keeps cement from flowing from the outside diameter of the casing back into the inside diameter of the casing. At this point the casing is filled with drilling fluid. 
   After being run the casing must be cut and finished at an appropriate level to install rig equipment such as blow out preventers along with other equipment. However, because of earlier operations, the entire length of casing is typically filled with drilling fluid. Depending on conditions, the length of casing which is to be cut and removed may therefore over a 100-foot (27.4 meter) column of drilling fluid therein. The drilling fluid in this section must be properly drained before the casing is cut and removed. 
   Prior art systems for removal of the drilling fluid in the casing have consisted of cutting an opening in the casing with a casing cutter, using tarpolines and a pan in an attempt to contain the escaping column of drilling fluid in the casing to be removed. Unfortunately, the prior art systems have been slow (taking up to many hours to drain) and allowing drilling fluid to and escape into the environment creating potential environmental hazards, such as pollution. Additionally, loss of fluids can be costly as the fluids are expensive and must be replaced. 
   While certain novel features of this invention shown and described below are pointed out in the annexed claims, the invention is not intended to be limited to the details specified, since a person of ordinary skill in the relevant art will understand that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation may be made without departing in anyway from the spirit of the present invention. No feature of the invention is critical or essential unless it is expressly stated as being “critical” or “essential.” 
   BRIEF SUMMARY 
   The apparatus of the present invention solves the problems confronted in the art in a simple and straightforward manner. What is provided is a fluid recovery system for recovering drilling fluid when cutting casing, such as a recovery system mountable on one or more joints of casing, a receiving tank, and a conduit between the recovery system and the receiving tank. A valve may preferably be provided for controlling flow through the conduit. 
   The method of the invention may preferably comprise steps such as the steps of mounting a recovery system on a joint of casing, creating a hole in the joint, and collecting the fluid in a receiving tank. The method may further comprise cutting the casing and removing the stand of casing above the cut. 
   The present invention provides a more efficient operation significantly improving the speed of draining drilling fluid, improving safety, and reducing well fluid loss into the environment. 
   It is an object of the present invention to provide an improved fluid recovery system. 
   Another object of the present invention is to have the ability to reduce the time required for setting up the well bore fluid recovery system. 
   Another object of the present invention is to have the ability to reduce any discharge of drilling fluids. 
   These and other objects, features, and advantages of the present invention will become apparent from the drawings, the descriptions given herein, and the appended claims. The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
       FIG. 1  is a schematic view of the prior art system for recovering drilling fluid. 
       FIG. 2  is a schematic view of a preferred embodiment of the present invention being used to recover drilling fluid. 
       FIG. 3  is a perspective view of the recovery system in  FIG. 2 . 
       FIG. 4  is a perspective view of the body of the recovery system in  FIG. 3 . 
       FIG. 4A  is a perspective view of the drill used in the recovery system shown in  FIG. 3 . 
       FIG. 5  is a side view of the body of the recovery system in  FIG. 3 . 
       FIG. 6  is a perspective view of the mounting rack for the recovery system in  FIG. 3 . 
       FIG. 7  is a perspective view of a portion of the recovery system in  FIG. 2 . 
       FIG. 8  is a perspective view of a shaft and drill bit for the recovery system in  FIG. 2 . 
       FIG. 9  is an exploded view of the shaft and drill bit for the recovery system in  FIG. 2 . 
       FIG. 10  is a top view of a portion of the recovery system in  FIG. 2 . 
       FIG. 11  is a perspective view of a portion of the recovery system in  FIG. 2 . 
       FIG. 12  is a side view of a portion of the clamp of the recovery system in  FIG. 2 . 
       FIG. 13  is an end view of the coupling of the recovery system in  FIG. 2 . 
   

   DETAILED DESCRIPTION 
   Detailed descriptions of one or more preferred embodiments are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in any appropriate system, structure or manner. 
   It will be understood that such terms as “up,” “down,” “vertical” and the like are made with reference to the drawings and/or the earth and that the devices may not be arranged in such positions at all times depending on variations in operation, transportation, and the like. As well, the drawings are intended to describe the concepts of the invention so that the presently preferred embodiments of the invention will be plainly disclosed to one of skill in the art but are not intended to be manufacturing level drawings or renditions of final products and may include simplified conceptual views as desired for easier and quicker understanding or explanation of the invention. As well, the relative size of the components may be greatly different from that shown, e.g., a recovery or well bore fluid storage tank  120 , discussed below, may typically be much larger than as shown. 
     FIG. 1  is a schematic view of a prior art system for recovering drilling fluid  105 . A casing cutter  400  is used to make a cut in casing  20 . Column of drilling fluid or mud  104  located in upper section of casing  30  above the cut is then drained in pan  420 . Pan  420  can be placed on deck  70 . Tarpoline  410  is placed over the cut in an attempt to minimize the loss of drilling fluid  106 . Such prior art method is slow, taking up to several hours to drain column of drilling fluid  104  and can require the presence of three to four rig hands. Additionally, there is the risk of spillage of drill fluid  106  which can spray outside of tarpoline  410  or away from pan  420 . Furthermore, tarpoline  410  is saturated with drilling fluid and must be properly disposed of. 
     FIG. 2  is a schematic view of a preferred embodiment of the present invention being used to recover column of drilling fluid or mud  104  in upper section of casing  30 . Recovery system  10  is installed on casing  20  and an opening in casing  20  is made through hole  185 . Recovery system  10  can be connected to recovery tank  120  and column of drilling fluid or mud  104  is drained through hole  185 . Column of drilling fluid or mud  104  is located in upper section of casing  30  and above the hole drilled through hole  185 . Pump  130  can be used to increase the rate of drainage of column of drilling fluid or mud  104 . Lower section of casing  40  can then be properly finished. 
     FIG. 3  is a perspective view of the recovery system  10  in  FIG. 2 . Recovery system  10  can be comprised of body  150  and mounting rack  300 .  FIG. 4  is a perspective view of body  150  of the recovery system  10  in  FIG. 3 .  FIG. 5  is a side view of body  150  of recovery system  10  in  FIG. 3 . 
   Body  150  can be comprised of clamp  160 , tube  210 , and drill  260 . 
   Clamp  160  can be comprised of first portion  170 , second portion  180 , nipple  220 , and a plurality of fasteners  190 . Hole  185  can be included in second portion  180 . Clamp  160  and hole  185  preferably make a fluid tight seal with casing  20  after an opening in casing  20  is made through hole  185 . Clamp  160  can be sized based on the diameter of casing  20  to be drained. Nipple  220  can be attached to second portion  180  and nipple  220  can be threaded. Clamp  160  can also be removably connected to tube  210  (e.g., by a threaded connection with nipple  220 ) and a plurality of clamps  160  can be included to address different size casings  20 . Any conventionally available fastening method can be used in place of fasteners  190 . For example, first and second portions  170 , 180  can be pivotally connected on one side with a locking bracket on the other. However, a plurality of bolted fasteners  190  is preferred to accommodate variations in diameter of casing  20 . 
   Clamp  160  can also include liner  200  which assists in making a fluid tight seal against the surface of casing  20 . Liner  170  can be any conventionally available sealing material such as rubber, teflon, cork, paraffin, wax, plastic, metal, polymer, and other sealing materials. Liner  170  is shown covering first and second portions  170 , 180 , however, liner  170  can be placed only on second portion  180  or limited to the area around hole  185 , such as a washer or o-ring configuration. 
   Tube  210  can be connected to clamp  160  and drill  260 . Tube  210  can comprise T-connector  230  and coupling  250 . Valve  240  can be threadably connected to T-connector  230 . Valve  240  can include arm  241  and can be any conventionally available valve such as a ball valve, gate valve, or other commercially available valve. T-connector  230  can be threadably connected to nipple  220 . Coupling  250  can comprise a seal (e.g., O-rings  253 , 254 ) which sealingly and slidably connects shaft  280  to coupling  250 . Coupling  250  can also comprise a lubrication fitting  251 , which can be used to lubricate relative movement (longitudinal and rotational) between shaft  280  and tube  210 . Guard  312  can be attached to bracket  300  to protect against movement of shaft  280  and motor  270 . 
     FIG. 4A  is a perspective view of the drill  260  used in recovery system  10  shown in  FIG. 3 . Drill  260  can be comprised of motor  270 , shaft  280  and drill bit  290  (or hole saw). Motor  270  is preferably pneumatically powered to minimize the risk of explosion. Depth  293  of drill bit  290  (or hole saw) should be sized to at least accommodate the thickness of wall of casing  20  in which an opening is to be made through hole  185 . Diameter  294  of drill bit  290  (or hole saw) should be sized to accommodate flow of column  104  of drilling fluid or mud, but also pass through hole  185 . Drill bit  290  (or hole saw) can be any conventionally available drill bit and can also include a pilot bit to ease initial drilling of wall of casing  20 . It is to be understood that a hole saw is a special type of drill bit. 
     FIG. 7  is a perspective view of a portion of body  150  including clamp  160 , valve  240 , T-connector  230 , and coupling  250 . Valve  240  can include handle  241  and coupling  250  can include lubrication fitting  251 .  FIG. 8  is a perspective view of shaft  280  including drill bit  290 , and base  281 . Drill bit  290  can include pilot drill bit  291  attached to the center of bit  290 . Drill bit  290  attaches to shaft  280  and shaft  280  attaches to base  281 . Base  281  attaches to motor  270 .  FIG. 9  is an exploded view of shaft  280  and drill bit  290 . Drill bit  290  can include base  292  and base  292  attaches to shaft  280 . 
     FIGS. 10-11  illustrate insertion of drill bit  290  into body  150  through hole  185 .  FIG. 10  is a top view of a portion of body  150 . Shaft  280  is partially inserted into body  150  through hole  185 .  FIG. 11  is another perspective view of a portion of body  150  with drill shaft  280  partially inserted into body  150  through hole  185 . 
     FIGS. 12-13  illustrate longitudinal passage  186  through body  150 .  FIG. 12  is a side view of a portion of body  150  showing hole  185  and longitudinal passage  186 . Longitudinal passage  186  can extend from hole  185  of section portion  180  through coupling  250  to end  256 . T-connector  230  provides an alternative path from passage  186  when valve  240  is in an open position.  FIG. 13  is an end view of coupling  250  showing passage  186 . O-rings  253 , 254  can be used to make a fluid tight seal between shaft  280  and coupling  250 . Port  255  for lubrication fitting  251  can be used to allow lubrication to be injected between O-rings  253 , 254  and facilitate rotation/sliding between shaft  280  and O-rings  253 , 254 . 
     FIG. 6  is a perspective view of the mounting rack  300  for the recovery system  10  in  FIG. 3 . Mounting rack  300  can be comprised of mounting bracket  310 , body  320 , drive shaft  340 , crank  350 , and base  330  for motor  270 . Mounting bracket  310  can have V-cuts  311  to attach to the wall of casing  20 . V-cuts  311  can be triangular or semicircular shaped. Motor  270  can be mounted on base  330 . Base  330  can be threadably connected to drive shaft  340  and track along length of body  320 . Turning crank  350  in the direction of arrow  351  can move base  330  in a longitudinal direction of arrow  352 . Turning crank  350  in the opposite direction can move base  330  in the opposite direction. Connectors  380  and arms  360  can be used with chain  360  (shown in  FIG. 2 ) to mount rack  300  on casing  20 . 
   Before attaching recovery system  10  to casing  20 , body  150  is attached to mounting rack  300 . Clamp  160  was sized for the particular diameter of casing  20 . First portion  170  is removed from clamp  160 . Recovery system  10  is placed against casing  20  aligning hole  185  approximately at the location where casing  20  is ultimately to be cut. Mounting bracket  310  is placed against the wall of casing  20 . Second portion  180  of clamp  160  should also mount against the wall of casing  20 . Chain  360  is wrapped around casing  20 , arms  370  and connected to connectors  380 . First portion  170  of clamp  160  is attached to second portion  180  via fasteners  190 . Liner  200  will make a fluid tight seal with wall of casing  20 . Recovery system  10  can then be connected to pump  30  and recovery tank  120  through hoses  134  and  135 . 
   After being connected to casing  20 , motor  270  is started which rotates shaft  280  and drill bit  290  in longitudinal passage  186  of body  150 . As shown in  FIG. 6 , crank  351  can be rotated in the direction of arrow  351  causing base  330  and drill  270  to move in the direction of arrow  352 . Shaft  280  and drill bit  290 , which are both located in longitudinal passage  186 , also move in the direction of arrow  352 . Drill bit  290  will pass through opening  185  and contact the wall of casing  20 . Pilot drill bit  291  will first contact wall of casing  20  making a pilot hole and steadying the drilling by drill bit  290 . Drill bit  290  will continue through the wall of casing  20  creating an opening the size of drill bit  290 . The portion of the wall of casing  20  which is cut out will be contained in the interior of drill bit  290 . Crank  350  is then turned in the opposite direction of arrow  351  causing drill bit  290  move in the opposite direction as arrow  352  and to recess into longitudinal passage  186 . 
   Column of drilling fluid or mud  104  will enter hole  185  and into longitudinal passage  186  of tube  210 . O-rings  253 , 254  sealing contact with shaft  280  will prevent drilling fluid or mud  104  from exiting from coupling  250 . Liner  200  prevents spillage of column of drilling fluid or mud  104  from between casing  20  and clamp  160 . Instead, flow of column of drilling fluid or mud  104  is directed from longitudinal passage  186  to valve  240  which can be opened via handle  241 . Flow will continue through hose  134 , pump  130 , hose  135  and into receiving tank  120 . Pump  130  can be used to greatly increase the flow of column of drilling fluid or mud  104  compared to gravity feed of the column. 
   After column of drilling fluid or mud is drained, recovery tool  10  is removed from casing  20  and casing  20  is cut using casing cutter  400  creating upper section of casing  30 . Upper section of casing  30  is then removed and lower section of casing  40  is prepared for further work related to oil and gas production. 
   While system  10  is shown as being constructed with most elements located below rig floor  17  where tanks  30  and  40  are conveniently out of the way, fluid recovery system  10  could also contain one or more tanks above the rig floor or positioned as is convenient for rig conditions. 
   The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and it will be appreciated by those skilled in the art, that various changes in the size, shape and materials, the use of mechanical equivalents, as well as in the details of the illustrated construction or combinations of features of the various elements may be made without departing from the spirit of the invention. 
   The following is a list of reference numerals: 
   
     
       
             
           
             
             
           
             
             
           
         
             
                 
             
             
               LIST OF REFERENCE NUMERALS 
             
           
        
         
             
               (Reference No.) 
               (Description) 
             
             
                 
             
           
        
         
             
               10 
               recovery system 
             
             
               20 
               casing 
             
             
               30 
               upper section of casing 
             
             
               40 
               lower section of casing 
             
             
               50 
               rig 
             
             
               60 
               rig floor 
             
             
               70 
               deck 
             
             
               80 
               deck 
             
             
               90 
               water surface 
             
             
               100 
               drilling fluid or mud 
             
             
               104 
               column of drilling fluid or mud 
             
             
               105 
               drilling fluid or mud 
             
             
               106 
               drilling fluid or mud 
             
             
               110 
               drilling fluid or mud 
             
             
               120 
               recovery tank 
             
             
               130 
               pump 
             
             
               134 
               hose 
             
             
               135 
               hose 
             
             
               150 
               body of recovery system 
             
             
               160 
               clamp 
             
             
               170 
               first portion of clamp 
             
             
               180 
               second portion of clamp 
             
             
               185 
               hole 
             
             
               186 
               longitudinal passage 
             
             
               190 
               fasteners 
             
             
               200 
               liner 
             
             
               210 
               tube 
             
             
               220 
               nipple 
             
             
               230 
               T-connector 
             
             
               240 
               valve 
             
             
               241 
               handle 
             
             
               250 
               coupling 
             
             
               251 
               lubrication fitting 
             
             
               253 
               O-ring 
             
             
               254 
               O-ring 
             
             
               255 
               port for lubrication fitting 
             
             
               256 
               end of coupling 
             
             
               260 
               drill 
             
             
               270 
               motor 
             
             
               280 
               shaft 
             
             
               281 
               base 
             
             
               282 
               end 
             
             
               283 
               keyway 
             
             
               290 
               drill bit (or hole saw) 
             
             
               291 
               pilot drill bit 
             
             
               292 
               base of drill bit 
             
             
               293 
               arrow 
             
             
               294 
               arrow 
             
             
               300 
               mounting rack of recovery system 
             
             
               310 
               mounting bracket 
             
             
               311 
               V-cut 
             
             
               312 
               guard 
             
             
               320 
               body 
             
             
               330 
               base for motor 
             
             
               340 
               drive shaft (which can be threaded) 
             
             
               350 
               crank 
             
             
               351 
               arrow 
             
             
               352 
               arrow 
             
             
               360 
               chain 
             
             
               370 
               arm 
             
             
               380 
               connector 
             
             
               400 
               casing cutter 
             
             
               410 
               tarpoline 
             
             
               420 
               pan 
             
             
                 
             
           
        
       
     
   
   All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise. 
   It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention set forth in the appended claims. The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.