Abstract:
An improved cuttings system located adjacent a drilling rig&#39;s shale shaker system utilizing a vacuum collection/gravity fed processing system, thereby eliminating expensive and complicated cuttings transfer systems. The use of a vacuum cuttings collection system combined within a common fluid-filled open tank and submersible grinding pumps eliminate the need for extensive circulating and holding systems. Cuttings are sized and chemically prepared within the same tank and fed directly to an injection pump for discharge to cuttings transport tanks or injected down hole. Other improvements include non-restrictive cuttings sizing, filtering, and an injection pump cuttings relief system.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuing application of presently pending U.S. patent application Ser. No. 11/286,476 filed Nov. 26, 2005. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to an improved processing system for preparing drill cuttings for injection into a well formation while drilling and more particularly to an improved process for sizing and processing the drill cuttings into a particulate matter for injection into cavities within the formation surrounding a well bore while drilling. 
     GENERAL BACKGROUND 
     When drilling for oil and gas, or other types of wells, a hole is bored into the earth, typically by a drill bit. Drilling mud containing various cuttings fluids are circulated in and out of the well, lubricating the drill bit and carrying away the rock shale, sand, and earth being removed from the bore. The material being removed from the bore is called drill cuttings. While the drilling fluid is necessary to the drilling operation, the sheer nature of its formulation makes the mud a contaminant to the environment. Once the contaminated drill cuttings and drill fluid are circulated out of the well, the contaminated fluid and drill cuttings are circulated to a shaker system where the contaminant fluid and drill cuttings pass over a screen on the shakers and other fluid cleaning equipment where the drilling mud and fluids are substantially separated from the drill cuttings. 
     Drill cuttings contaminated with drilling mud and their various drilling fluids remain a contaminant to the environment and must be handled in an environmentally safe way. Therefore, several inventions have been developed to handle, transport, clean, dry, grind, and/or inject the contaminated drill cuttings and the residual drilling fluids adhering thereto back into the earth formation surrounding the well bore in an efficient and economical manner and in a way that does not restrict or choke the well&#39;s drilling production rate. Yet problems still persist that cause production delays due to an inability to process, transport, and dispose of the drill cuttings and economically recover and handle the residual drilling fluid contaminates. These problems are present in virtually all drilling operations. 
     Cuttings grinding and disposal systems as taught by the prior art have substantially improved the cuttings processing and disposal operations by injecting them back in the earth formation as the well is being drilled. Although vastly improved, such systems are complicated by numerous valves, manifolds, shakers, pumps, adjustable jets, etc., a plurality of tanks and circulatory systems, and further include separate injection skids that require supercharged pumps to expand the earth formations for injection. Although such systems performed the desired function of cuttings injection, several highly trained personnel are required to operate and maintain such systems. These systems have high operating costs, and use considerable deck space. Throughput for these cuttings injection systems have been improved over the years as a result of the addition of more and more sophisticated equipment added to the system to better prepare the cuttings for injection, such as the addition of secondary shakers, and grinding mills. Manifolds and adjustable jets were added to minimize the shutdown times for cleanout of oversize cuttings from the pump units. Improvements to manifolds and valves were made to correct pumps that wore out or plugged quickly. 
     In short, the cuttings processing and injection systems currently in use are a patchwork of makeshift add-ons used to solve immediate problems in the field. 
     The cuttings processing and injection system disclosed herein addresses the entire cuttings injection process as a whole and simplifies the process by eliminating choke points, thus improving throughput by improving flow paths, reducing equipment and over-all system size, reducing wear and thus lowering maintenance cost, reducing power consumption, and reducing manpower requirements while improving system reliability. 
     SUMMARY OF THE INVENTION 
     The disclosed invention is an improved drill cuttings processing system for well injection. The new and improved cuttings system is capable of being placed adjacent the drilling rig&#39;s shale shaker system and thus allowing use of gravity feed system and or a cuttings vacuum collection system, thereby eliminating expensive and complicated cuttings transfer systems. The use of an innovative vacuum cuttings collection system and the use of submersible in tank grinding pumps eliminate the need for extensive circulating and holding systems. Cuttings may be sized and chemically prepared within the same tank and fed directly to an injection pump or held in an adjacent make-up tank when necessary. Other embodiments disclose processes for non-restrictive cuttings sizing, filtering, and injection pump relief systems. 
     In operation the improved drill cuttings collection and processing system, including its injection pump system, utilizes a high velocity vacuum system for suctioning drill cuttings into an inverted hopper having its open end submerged in any open, fluidized container. The cuttings drop by gravity from the inverted hopper into the fluidized container where they are agitated and ground by submersible pumps located within the container into a fine particulate matter suitable for injection. The cuttings particulate within the fluidized container is selectively drawn into the inlet of an injection pump for discharge into a well bore. 
     It can be seen that open, fluidized containers allow easy access to the grinding pumps and visual inspection of the cuttings slurry. Further, the improved drill cuttings processing system reduces space requirements, utilizes onboard existing equipment whenever possible, reduces personnel, and reduces downtime and operating cost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which, like parts are given like reference numerals, and wherein: 
         FIG. 1  is side elevation view of the improved cutting injection system; 
         FIG. 2  is a top view of the improved cuttings injection system; 
         FIG. 3  is a side elevation cross-section view of the improved cuttings system with makeup tank; 
         FIG. 4  is a side elevation cross-section view of the improved cuttings system with dual submersible grinders; 
         FIG. 5  is a side elevation cross-section view of the improved cuttings system with submersible grinder and impingement control; 
         FIG. 6  is a side elevation cross-section view of the rotating screen assembly identified as detail  6  seen in  FIG. 3 ; 
         FIG. 7  is a side elevation cross-section view of a non-rotating screen assembly identified as detail  7  seen in  FIG. 4   FIG. 8  is a partial cross-section view of the valve assembly seen in  FIG. 5 ; 
         FIG. 9  is a cross-section view of the screen assembly seen in  FIG. 6  taken along sight lines  9 - 9 ; and 
         FIG. 10  is an end view of the triplex pump inlet and outlet manifold. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in  FIG. 1 , the improved injection system  10  includes a open top receiving tank  12  that may be supplied on a skid  14  or provided by the drill site thus reducing the need for additional special equipment on site. In any which case the vacuum units and injections pump units  16  and  19  respectively may be mounted on separate or combined equipment skids as shown or independent of the tank unit  12 . In any case a set of steps  20  or ladder for accessing the top of the open receiving tank is generally provided for workers to visually inspect and control the inflow of cuttings through tubing  22  to the receiving tank  12  from shaker screens or other cuttings processing systems via conventional conveying systems or the vacuum hood or plenum  24  and vacuum pump  16  as shown. In this configuration vacuum is maintained on the hood or plenum  24  via the pump or blower  16  suction line  23 . Cuttings drop by gravity from an open portion of the hood or plenum  24  submerged into the liquid filled receiving tank  12  where they are continuously agitated and sized via grinding pumps located within the open top receiving tank, forming a slurry of entrained finely ground cuttings and a carrier fluid, before being drawn into the inlet line  26  of an injection pump unit  30  at low pressure for discharge via line  27  into cuttings boxes or high pressure for disposal or injection into the well casing annulus and/or forced into the formation cavities and fractures surrounding a well bore being drilled. Air and hydraulic control panels  34  and electric power panel  36  respectively may be attached to or placed on the upper decking  32  as shown in  FIG. 2 . Handrails  37  may be added as need to secure the safety of the operating personnel. It is important to note that visual inspection of the cuttings slurry within the liquid filled tank  12  is an important aspect of the cuttings injection process. It is also important for the liquid levels  42  within the receiving tank to be maintained at all times to insure suction on the vacuum hood or plenum  24 . 
     Looking now at  FIG. 3 , we see the receiving or cuttings tank  12  in cross-section is divided into two tanks by partition  39 , the slurry-grinding tank  38  and the slurry make-up tank  40 . It is essential that slurry liquid  42  in each tank be maintained at a constant level. We also see that submersible grinders  44  are utilized for sizing the cuttings and maintaining the cuttings in constant state of agitation within the grinding tank. The grinders  44  may be placed in opposition to each other in a manner whereby the grinder/pump discharge outlets  46  force cuttings to collide under pressure, thereby further reducing their size. It can also be seen that a filter screen assembly  48  is provided to insure that only properly sized cuttings are allowed to enter the make-up tank  40 . In some cases this filter screen assembly may be rotated to prevent cuttings build up on the surface of the filter screen. A more detailed view of this arrangement may be seen in  FIG. 6 . The cuttings slurry being discharged from the filter screen assembly  48  into the make-up tanks  40  is drawn into the inlet tube  26  of the injection pump  30  and discharged under high pressure to a well bore annulus. 
     In some cases it may be possible to utilize a single grinding tank  42 , as shown in  FIG. 4 , where the filter screen assembly  48  is fixed and attached directly to the inlet  26  of the injection pump  30  for high pressure discharge to the well annulus and its surrounding formation cavities and/or fractures. 
     Submersible centrifugal grinder pump  44  is fitted with a special impeller having carbide inserts to reduce wear and insure proper grinding of the cuttings. The pump may be located adjacent an impingement plate  50 , as shown in  FIG. 5 , so that the cuttings are directed onto the plate  50  under pressure. This arrangement further reduces clumping and further sizes the cuttings. Submerged centrifugal pumps such as seen in  FIG. 5  may be fitted with a variable orifice discharge port such as a valve assembly  52  having an extended actuator rod and handle as further detailed in  FIG. 8 . However, the adjustable orifice or valve assembly  52  may be attached directly to the discharge outlet  46  of the grinder/pump  44 . The valve assembly  52  is usually controlled from the upper deck  32 . It is important to understand the need to reduce the discharge orifice size of the pump by up to 50 percent to ensure sufficient grinding residence within the grinder/pump  44 . Float assembly  54  attached to the cuttings hood  24  may automatically control the level of slurry  42  in the slurry tank  38 . 
     As previously mentioned, the filter screen assembly  48  may be made rotatable, as shown in detail in  FIG. 6 . In this case a hollow shaft gear reducer assembly  56  is mounted to the make-up tank side of the partition wall  39  and driven by either a pneumatic, hydraulic, or electric gear motor  58 . A tubular shaft  64  with a plurality of holes  60  therein is inserted through the hollow shaft portion of the gear reducer  62  and secured therein. The linear screen assembly  48  is secured to the tubular shaft  64  surrounding the holes and in a manner whereby the linear screen allows the passage of the proper size cuttings in the slurry to pass the screen  66  and to enter the holes  60  for discharge into make-up tank. However, the linear screen  66  may be non-rotatably fitted to the wall of the tank  38  and attached directly to the intake tube  26  as shown in  FIG. 7 . 
     As further detailed in  FIG. 8 , the valve assembly  52  previously mentioned shows that the spade portion  70  of the valve assembly  52  has a “V” shaped notched opening  72  which provides an inability to fully close off material flow though the valve. This prevents the possibility of placing the grinding pump  44  in a fully blocked condition, thus producing pump cavitations. 
     As shown in  FIG. 9 , the filter screen  66  is composed of a series of longitudinal triangular bars  74  held in a spaced-apart configuration, thus allowing only the properly sized cuttings to pass. Such screens are fabricated for a particular use and are widely used in the industry where heavy material loads and pressures are encountered. 
     Looking at  FIG. 10 , a crossover or feedback relief system  80  is provided for releasing the pressure on the slurry being pumped from the grinding tank  38  or the make-up tank  40  for discharge to cuttings holding tanks or directly to a well for injection in the annulus and/or fractures down hole. The crossover relief system  80  may be constructed in a variety of ways but the preferred embodiment is simply a loop or manifold tube  82  connected at one end to the discharge tube  27  and at the opposite end to the pump inlet tube  26  with a ball valve  84  there between. The ball valve  84  may be operated to an open or closed position by a rotary actuator assembly  86 , which may be hydraulic or electrically driven as required to increase or decrease pressure on the discharge line  27 . 
     Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in any limiting sense.