Patent Publication Number: US-8533974-B2

Title: Reclamation of components of wellbore cuttings material

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/469,851 filed on May 21, 2009, which is a division of U.S. patent application Ser. No. 11/543,301 filed on Oct. 4, 2006 and incorporated by reference herein for all they contain. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to systems and methods for reclaiming components of wellbore drilling cuttings mixtures; and in one aspect, to transferring dried lean phase cuttings materials to other systems. 
     2. Description of the Related Art 
     Drilling fluids—typically called “muds”—used in hydrocarbon well drilling, as well known in the prior art, pick up solid cuttings and debris which must be removed if the fluid is to be re-used. These fluids are typically water based or oil-based. Often a mud with various additives is pumped down through a hollow drill string (pipe, drill collar, bit, etc.) into a wellbore and exits through holes in a drillbit. The mud picks up cuttings, rock, other solids, and various contaminants, such as, but not limited to, crude oil, water influx, salt and heavy metals from the well and carries them upwardly away from the bit and out of the well in a space between the well walls and the drill string. The mud is pumped up the wellbore and at the top of the well the contaminated solids-laden mud is discharged, e.g., to a shale shaker which has a screen or a series of screens that catch and remove solids from the mud as the mud passes through them. If drilled solids are not removed from the mud used during the drilling operation, recirculation of the drilled solids can create weight, viscosity, and gel problems in the mud, as well as increasing wear on mud pumps and other mechanical equipment used for drilling. 
     The prior art discloses a variety of drill cuttings treatment methods and systems, and methods for reinjecting processed drilling fluid back into a well, including, but not limited to, as disclosed in U.S. Pat. Nos. 4,942,929; 5,129,469; 5,109,933; 4,595,422; 5,129,468; 5,190,645; 5,361,998; 5,303,786; 5,431,236; 6,640,912; 6,106,733; 4,242,146 and 4,209,381—all of these patents incorporated fully herein for all purposes. In one example of a typical prior art system, land-based or offshore (e.g. as shown in U.S. Pat. No. 5,190,645), a well is drilled by a bit carried on a string of drill pipe as drilling mud is pumped by a pump into the drill pipe and out through nozzles in the bit. The mud cools and cleans the cutters of the bit and then passes up through the well annulus flushing cuttings out with it. After the mud is removed from the well annulus, it is treated before being pumped back into the pipe. The mud enters a shale shaker where the relatively large cuttings are removed. The mud then enters a degasser where gas can be removed if necessary. The degasser may be automatically turned on and off, as needed, in response to an electric or other suitable signal produced by a computer and communicated to degasser. The computer produces the signal as a function of data from a sensor assembly associated with shale shaker. The mud then passes to a desander and (or a desilter), for removal of smaller solids picked up in the well. In one aspect, the mud next passes to a treating station where, if necessary conditioning media, such as barite, may be added. Suitable flow controls e.g. a valve, control the flow of media. The valve may be automatically operated by an electric or other suitable signal produced by the computer as a function of the data from sensor assembly. From the treatment station, the mud is directed to a tank from which a pump takes suction, to be re-cycled through the well. The system shown is exemplary; additional components of the same types (e.g. additional treatment stations) or other types (e.g. centrifuges) are be included. 
     In another prior art system (e.g. as disclosed in U.S. Pat. No. 6,106,733) cuttings, debris, material, soil and fluid from a drilling operation in a wellbore W are conveyed to a shaker system. Separated oily solids (cuttings, soil, etc.) are conveyed with a conveyor (a pump may be used) to a thermal treatment system. The thermal treatment system produces a discharge of treated solids suitable for disposal and a stream containing liquids (e.g. oil and water). 
     In certain prior art systems and methods on an offshore rig wet cuttings, produced, e.g., by shale shakers, are mixed with sea water to form a mixture with a desired mud weight and viscosity which, in some aspects, results in a pumpable slurry. The resulting drilling fluid is then fed to a known cuttings reinjection system or to storage. Wet material generally weighs more and can occupy more volume than dry material. 
     A variety of problems are associated with certain prior art systems and methods which begin with wet drilling material, “wet” being defined as the fluid content of material taken directly from shale shakers. Cohesive bridging and arching of wet material are problems associated with attempts to process wet material to recover reusable drilling fluid. 
     There has long been a need for an effective and efficient system for treating drilling mixtures to recover reusable fluid and to process cuttings material for transfer and, in some cases, for reinjection into the earth. There has long been a need, recognized by the present inventor, for such systems which deal with dry drill cuttings material so it can be effectively handled and reinjected into the earth and which reduce the volume of cuttings material for ease of handling and economies of scale. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention teaches methods for reclaiming component materials from a drill cuttings mixture of drilling fluid and cuttings material, the methods in certain aspects including: flowing a drill cuttings mixture of drilling fluid and cuttings material to a dryer; producing with the dryer dry cuttings material; and conveying with a conveyor system the dry cuttings material to a secondary system, the conveyor system including a positive pressure pneumatic conveying apparatus for conveying the dry cuttings material to the secondary system. 
     The present invention teaches systems for separating drilling mixture components and for reinjecting cuttings material into a wellbore, the systems in certain aspects including: a dryer for producing dry cuttings material from a cuttings mixture of drilling fluid and cuttings material, the dryer in certain aspects for reducing in size pieces of material fed to it and, in one aspect, reducing material to powder; and a conveying system for conveying the dry cuttings material to a secondary system, e.g. a thermal treatment system or a reinjection apparatus, the conveying system including positive pressure pneumatic conveying apparatus. 
     The present invention discloses, in certain embodiments, a wellbore cuttings component reclamation system that processes cuttings material from a wellbore drilling mixture and treats the cuttings material to produce acceptably disposable material (in certain aspects for transfer to a thermal treatment facility and subsequent landfill disposal; or for reinjection, e.g. into a dedicated reinjection well or through an open annulus of a previous well into a fracture, e.g. a fracture created at a casing shoe set in a suitable formation and, in certain aspects, recyclable drilling fluid. Such systems may be land-based or configured for offshore use. 
     In certain embodiments, a system according to the present invention has cuttings material processed by a dryer, e.g. a vortex dryer, that produces relatively dry material containing primarily drill cuttings material and some drilling fluid. In one aspect “dry” material is material that is a powder-like substance able to be transferred or conveyed in lean (or “dilute”) phase (i.e. substantially all particulates contained in an air stream are airborne), facilitating transfer by a positive pressure pneumatic conveyor. Using a dryer that produces both dried cuttings material and drilling fluid can, according to the present invention, optimize or maximize the reclamation of drilling fluid (“mud”) and minimize the volume of cuttings material to be transported and/or treated prior to disposal. In certain aspects, by passing the cuttings material through a Vortex dryer or similar apparatus, the size of pieces of cuttings material is reduced and the transfer of such material is thereby facilitated; in one aspect, a Vortex dryer produces a powder from input cuttings material. In many instances, additional grinding of the material by an appropriate grinder apparatus facilitates treatment of the material by a shaker. Broken down material is slurrified more easily than relatively larger material; e.g., when, for reinjection, the material is mixed with seawater. By using a dryer that reduces size of material, wear and tear on downstream grinders is reduced. Using a positive pressure pneumatic conveying apparatus, dried cuttings material can be dosed into a treatment facility in a controlled manner. 
     Accordingly, the present invention includes features and advantages which are believed to enable it to advance drill cuttings conveyance technology. Characteristics and advantages of the present invention described above and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments and referring to the accompanying drawings. 
     Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures, functions, and/or results achieved. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention. 
     What follows are some of, but not all, the objects of this invention. In addition to the specific objects stated below for at least certain preferred embodiments of the invention, there are other objects and purposes which will be readily apparent to one of skill in this art who has the benefit of this invention&#39;s teachings and disclosures. It is, therefore, an object of at least certain preferred embodiments of the present invention to provide: 
     New, useful, unique, efficient, non-obvious systems and methods for the reclamation of drilling material components and which treat drill cuttings material to produce conveyable dry drill cuttings material conveyable by positive pressure pneumatic conveying apparatus on land-based or offshore drilling rigs; 
     Such systems and methods that provide for further treatment and/or processing of relatively dry cuttings material, including, but not limited to reinjection and thermal treatment; and 
     Such systems and methods that reclaim re-usable re-cyclable drilling fluids. 
     It will be understood that the various embodiments of the present invention may include one, some, or all of the disclosed, described, and/or enumerated improvements and/or technical advantages and/or elements in claims to this invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more particular description of embodiments of the invention briefly summarized above may be had by references to the embodiments which are shown in the drawings which form a part of this specification. These drawings illustrate certain preferred embodiments and are not to be used to improperly limit the scope of the invention which may have other equally effective or equivalent embodiments. 
         FIG. 1  is a schematic view of a system according to the present invention. 
         FIG. 2  is a side view in cross-section of part of the system of  FIG. 1  showing a mixer. 
         FIG. 3  is a side view in cross-section of part of the mixer in  FIG. 2 . 
         FIG. 4  is a schematic view of a system according to the present invention. 
     
    
    
     Presently preferred embodiments of the invention are shown in the above-identified figures and described in detail below. It should be understood that the appended drawings and description herein are of preferred embodiments and are not intended to limit the invention or the appended claims. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims. In showing and describing the preferred embodiments, like or identical reference numerals are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness. 
     As used herein and throughout all the various portions (and headings) of this patent, the terms “invention”, “present invention” and variations thereof mean one or more embodiment, and are not intended to mean the claimed invention of any particular appended claim(s) or all of the appended claims. Accordingly, the subject or topic of each such reference is not automatically or necessarily part of, or required by, any particular claim(s) merely because of such reference. 
     DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT 
     As shown in  FIG. 1 , one particular embodiment of a system  10  according to the present invention has a system  12  with a dryer  13  for producing dry cuttings material and then feeding the dry cuttings material in a line A to a system  14 , a positive pressure pneumatic conveying system that selectively conveys the dry material into the line B (for eventual reinjection). In one particular aspect the system  14  is a system as disclosed in co-owned U.S. Pat. Nos. 6,936,092 and 6,988,567 and U.S. application Ser. No. 10/875,083 filed Jun. 22, 2004, all incorporated fully herein for all purposes. In one aspect the dryer produces dried cuttings material in a powder-like form. 
     A sensor SR on the line A senses moisture content of the material in the line and conveys this information to a control system CS (e.g., but not limited to a control system as disclosed in the co-owned patents and U.S. patent applications listed above) which can shut down flow from the system  12 . The control system CS controls the various items, devices and apparatuses in the system  10  and, in one aspect, communicates with a control system CM of a cuttings reinjection system CRI. The control system CS can adjust the flow rate of dried material to a blender  24  using a standard PID algorithm with a setpoint based on acceptable density, feedback for which is obtained from a meter of the CRI system. 
     Material in a line B is conveyed to the blender  24 . Water (or sea water) from a tank  22  is circulated in lines D and C to the blender  24  by a pump  23 . The pump  23  pumps liquid from the tank  22  which mixes with the inflowing air flow from the line B in the blender  24 . A viscosity/density meter  28  provides the control system CS with information regarding the viscosity and density of the material flowing from the tank  22 . The cuttings material and water mix together and are pumped by the pump  23  through a screen  21  into the tank  22  of a first stage  20  of the system  10 . 
     Water (or sea water) as needed is fed into the tank  22  by a pumping system  25 . An agitator  26  helps maintain solids in suspension in the tank  22 . 
     Density (and weight) and viscosity of the mixture in the tank  22  are sensed by sensors (e.g. meter  28 , sensor ST) which convey sensed levels of density, weight, and viscosity to the control system CS, and, as needed, are adjusted by changing the feed from the system  14  using a control system CS  2  for the system  14  with the control system CS in communication with the control system CS  2 . A resulting slurry of the material is pumped by a pump  27  in a line E to a line G to a tank  32  or, optionally, first to a shaker system  34 . A control valve  29  selectively controls flow in the line G. When the tank&#39;s contents are at an acceptable density and/or viscosity, the valve  29  is opened, flow in Line B ceases, and the tank is emptied into the line G sending a batch of material to the tank  32 . The shaker system  34  removes oversize solids returned in a line F back to the tank  22 ; and drilling fluid with particles of material of an acceptable size (which pass through the shaker&#39;s screens) is fed in a line H to the tank  32  of a second stage  30 . Sensors SS sense levels of density, weight and viscosity of the material in the tank  32  and convey this information to the control system CS. As needed, weight and viscosity are adjusted. An agitator  36  agitates the contents of the tank  32 . A discharge rate of the system  14  is adjustable via adjusting a variable speed metering screw  14   a  of the system  14 . 
     Drilling fluid is pumped in lines I, J and K by a pump  33  for injection into a wellbore W e.g., for drilling operations employing pumped drilling fluid with valves VA and VB closed and valve VC open. Optionally, the pump  33  pumps material to the cuttings reinjection (“CRI”) system which may include a or several first stage booster pump(s) for a or several triplex pump(s) or similar pump(s) useful in cuttings reinjection. 
     Optionally, with valves VA and VC closed, the material from the tank  32  is pumped by the pump  33  in the line I, J, L to a storage facility T through valve VB. Optionally with the valves VB and VC closed, the pump  33  pumps material from the tank  32  in the lines I, J, M back into the tank  32  through valve VA for storage and/or further processing. 
     Any suitable known blender or mixer can be used for the blender  24  (e.g. a high shear mixing unit or mixer). In one aspect, as shown in  FIGS. 2 and 3 , the blender  24  has an inlet  31  in an upper body  38  into which dry material flows from the system  14 , e.g. in a continuously flowing air-conveyed stream. Liquid recirculated from the tank  22  flows into an inlet  32 , sucking material from the inlet  32 . A mixer  41 , e.g. an in-line static ribbon mixer, mixes the various flows. The material flows down a pipe  36  to a diffuser  39  which has a screen (or screens)  21  through which the material flows into the tank  22 . Numeral  34  indicates a typical level of material in the tank  22  and numeral  35  indicates a low level of the material. Dried material from the dryer  13  is reduced in size by the dryer. This lightens the load on downstream grinders and increases the efficiency of the blender  24  and results in a focused high energy interaction between the relatively smaller solids (in powder form) and water (e.g. seawater), optimizing or maximizing resultant homogeneity of the mixture fed to the tank  22 . Wear, tear and downtime of downstream grinders, e.g. grinder pumps of a CRI system are reduced due to the flow of the size-reduced material from the dryer. 
     As shown in  FIG. 3  the body  38  includes an interior flow member  37  through which the dry material flows and exits from an outlet  37   a  to mix with the incoming liquid flowing in from the inlet  32 . 
       FIG. 4  illustrates a system  100  according to the present invention in which a feed conveyor  110  conveys drill cuttings material processed by shakers  120  (e.g. on a land rig or offshore rig) either to a dryer  130  or to a cuttings container  140 . Recovered well drilling fluid (with some solids) from the dryer  130  is, optionally, fed in a line  215  to a holding tank  150  and then to a centrifuge  160  for centrifugal processing. Dried cuttings material from the dryer  130  is fed by a conveyor system  220  to a feeder system  170  (a positive pressure pneumatic conveying system), with a feeder  172  and an outlet  174 , to a tank system  180  from which it is fed to a cuttings reinjection system  190 . 
     Optionally, cuttings material from the tank system  180  is fed to a storage system  192  on a vessel  194  from which it is subsequently introduced to a cuttings reinjection system  196  at another site or rig. The system  170  can send the material to the tank system  180  and/or the tank system  180  can send the material to the system  190 . The system  100  may have a control system like the system CS,  FIG. 1 . 
     In one particular aspect the dryer  130  is a vortex dryer, e.g. a commercially available National Oilwell Varco Brandt Vortex Dryer which, optionally, can be flushed with liquid material from the holding tank  150  via lines  201 ,  202 ,  203 . Via lines  201 ,  202  and  204  material from the tank  150  is fed to the centrifuge  160 . Solids output by the centrifuge  160  flow in a line  205  to a conveyor  206  which transfers the solids in a line  207  to the container  140 . The holding tank  150  is a weir tank with a middle weir dividing the tank into two sides  151 ,  152 . 
     The feed conveyor  110  feeds material in a line  208  to the container  140  and in a line  209  to the dryer  130 . Recovered material flows from the dryer  130  to the tank  150  in a line  215 . Drilling fluid from the centrifuge  160  flows in a line  211  back to the tank  150 . Reusable drilling fluid flows from the tank  150  in a line  212  to a rig mud system  210 . Optionally, this fluid flows through a filtration system FL prior to introduction to the system  210 . Material in a line  214  from a side  151  of the tank  150  is fed back to the centrifuge in a line  201 . Material flows in a line  213  to the line  212 . A pump  218  pumps material in the line  201 . 
     The system  170 , which receives dry material from the dryer  130 , including a positive pressure pneumatic conveying system, including, e.g., those disclosed in the two U.S. patents and the pending U.S. patent application referred to above. Dry material from the dryer  130  is fed by the reversible conveyor  220  to the system  170  in lines  223 ,  224 . A moisture meter  230  measures the moisture level of material from the dryer  230  and, if the material&#39;s moisture content exceeds a pre-set level (e.g. 10% by weight)—a level at which conveyance by the positive pressure pneumatic conveying apparatus would be impeded or prevented—the reversible conveyor  220  reverses and the material is fed in the lines  221 ,  222  to the container  140 . In one aspect the dryer is a vortex dryer that produces the dry cuttings material as dry powder in lean phase. 
     Suitable valves, check valves, filters, flow controllers and controls for them are used on the lines of the system  100 . 
     Dry material from the system  170  is moved, in one aspect, to a suitable storage and processing system, e.g. a tank system  180  which may be any tank or vessel (or tanks or vessels) disclosed in the two U.S. patents and the U.S. patent application referred to above, including a vessel (land-based; on a rig; on a ship) which doses material to an apparatus or system (e.g. to the system  190  or to the system  196 ). The reinjection systems  190  and  196  may be like that of  FIG. 1  or they may be any suitable known cuttings reinjection system for reinjecting material into a wellbore. 
     In one particular aspect, if the moisture sensor  230  indicates that screens in the dryer  130  are blinding (indicating the moisture content of the material is too high for the conveying system to convey or to effectively convey the material), material from the dryer  130  is directed in the line  222  to the container  140 . Optionally, material from the system  170  is fed to a thermal treatment system  197  (from which it can then be transferred to the system  190  or to a transport for transfer to the system  196 . As with the transfer of material to the system  190 , material can be sent directly from the system  170  to the system  197 , or to the system  180  and then to the system  197 . 
     The present invention, therefore, provides in some, but not necessarily all, embodiments a method for reclaiming component materials from a drill cuttings mixture of drilling fluid and cuttings material, the method including: flowing a drill cuttings mixture of drilling fluid and cuttings material to a dryer; producing with the dryer dry cuttings material; and conveying with a conveyor system the dry cuttings material to a secondary system, the conveyor system including a positive pressure pneumatic conveying apparatus for conveying the dry cuttings material to the secondary system. Such a method may include one or some, in any possible combination, of the following: wherein the secondary system is a cuttings reinjection system, the method further including reinjecting the dry cuttings material into a wellbore using the cuttings reinjection system; sensing moisture content of the dry cuttings material; if the moisture content indicates that the dry cuttings material will impede conveyance by the conveyor system, diverting the dry cuttings material away from the positive pressure pneumatic conveying apparatus; producing with the dryer a drilling fluid mixture with some solids from the drill cuttings mixture, and flowing the produced drilling fluid mixture from the dryer with some solids to a holding system; flowing the drilling fluid mixture from the holding system to a rig mud system; flowing drilling fluid mixture from the holding system to a centrifuge for processing by the centrifuge to produce centrifuged solids and centrifuged drilling fluid; flowing the centrifuged drilling fluid to the holding system; the conveyor system including a reversible conveyor, the method further including reversing the reversible conveyor to prevent dry drill solids from the dryer from flowing to the positive pressure conveying apparatus; wherein the secondary system is a thermal treatment system, the method further including treating the dry cuttings material with the thermal treatment system; dosing material from the positive pressure pneumatic conveying apparatus to the secondary system; wherein a primary control system controls operations of the system and a secondary control system controls the cuttings reinjection system, the secondary control system in communication with the primary control system, the method further including adjusting using the primary control system a rate of feed of material to a mixer, and feeding material from the mixer to the cuttings reinjection system; wherein the secondary control system provides density measurements from a density meter to the primary control system, the primary control system taking said measurements into account in said adjusting; wherein the cuttings material includes pieces of material, each piece having a size, the method further including the dryer reducing the size of said pieces; and/or wherein the dryer reduces the pieces to powder. 
     The present invention, therefore, provides in some, but not necessarily all, embodiments a method for reclaiming component materials from a drill cuttings mixture of drilling fluid and cuttings material, the method including: flowing a drill cuttings mixture of drilling fluid and cuttings material to a dryer; producing with the dryer dry cuttings material; conveying with a conveyor system the dry cuttings material to a reinjection system, the conveyor system including a positive pressure pneumatic conveying apparatus for conveying the dry cuttings material; reinjecting the dry cuttings material into a wellbore using the reinjection system; sensing moisture content of the dry cuttings material; the conveyor system having a reversible conveyor, the method further including if the moisture content of the dry cuttings material is of such a level that conveyance by the conveyor system would be impeded, reversing the reversible conveyor to prevent dry cuttings material from the dryer from flowing to the positive pressure conveying apparatus. 
     The present invention, therefore, provides in some, but not necessarily all, embodiments a system for separating drilling mixture components and for reinjecting cuttings material into a wellbore, the system including: a dryer for producing dry cuttings material from a cuttings mixture of drilling fluid and cuttings material; a conveying system for conveying the dry cuttings material to a reinjection apparatus, the conveying system having positive pressure pneumatic conveying apparatus; and a thermal treatment apparatus or a reinjection apparatus for reinjecting the dry cuttings material into a wellbore. Such a method may include one or some, in any possible combination, of the following: a moisture sensor for sensing moisture content of the dry cuttings material, and the conveyor system further having a reversible conveyor, the reversible conveyor for feeding the dry cuttings material to the positive pressure pneumatic conveying apparatus and for reversing, if the moisture content of the dry cuttings material is such that conveyance by the positive pressure pneumatic conveying apparatus would be impeded, so that the dry cuttings material do not flow to the positive pressure pneumatic conveying apparatus; a centrifuge for receiving a drilling fluid stream from the dryer, the drilling fluid stream containing reclaimable drilling fluid, and the centrifuge for processing the drilling fluid stream from the dryer producing reusable drilling fluid; and/or wherein the dryer is for reducing in size the size of pieces of cuttings material, in one aspect, to powder. 
     In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited herein is to be understood as referring to the step literally and/or to all equivalent elements or steps. This specification is intended to cover the invention as broadly as legally possible in whatever form it may be utilized. All patents and applications identified herein are incorporated fully herein for all purposes.