Abstract:
A method and apparatus for disposing of drill cuttings includes collecting drilling mud from a wellbore, the drilling mud comprising liquid and solids, separating the liquid from the solids in a first separation step, separating the liquid from the solids in a second separation step, and transferring the solids to a container with a vacuum pump.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    Embodiments of the invention generally relate to removing solids from liquid. More particularly, embodiments of the invention relate to a method and system for disposing of drill cuttings from drilling fluids. 
         [0003]    2. Description of the Related Art 
         [0004]    Drilling rigs are used to extract oil, gas, and other hydrocarbons from sub-surface formations. A drill string is typically lowered down hole, and a drill bit at the end of the drill string is rotated to cut into the mineral deposits in the sub-surface formations. Drilling fluid, such as drilling mud, is pumped through the drill bit during the drilling operation to help facilitate the drilling process, and the drilling mud with cuttings from the wellbore are circulated back up to the surface in an annular area formed between walls of the wellbore and the drill string where the mud is separated from the cuttings for re-use. 
         [0005]    Various methods and systems are used to remove and dispose of drill cuttings, but they are inefficient and/or produce unwanted waste at a work site. Therefore, there is a need for improved methods and systems of disposing of drill cuttings that overcomes the present issues. 
       SUMMARY OF THE INVENTION 
       [0006]    In one embodiment, the invention includes a method for disposing of drill cuttings that includes collecting drilling mud from a wellbore, the drilling mud comprising liquid and solids, separating the liquid from the solids in a first separation step, separating the liquid from the solids in a second separation step, and transferring the solids to a container using a vacuum pump. 
         [0007]    In one embodiment, the invention includes a system used to dispose drill cuttings comprising a first shaker, a second shaker, a vacuum pump, and a removable container. Drilling mud, which contains liquid and solids, is passed through the first and second shakers to separate the liquid from the solids, and the vacuum pump moves the solids to the removable container. 
         [0008]    In one embodiment, the invention includes a method of disposing of drill cuttings comprising collecting drilling mud from a wellbore, the drilling mud comprising liquid and solids, separating the solids from the liquid, and transferring the solids to a container with a vacuum pump. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    So that the manner in which the above recited features of the invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
           [0010]      FIG. 1  is a schematic view of a system for disposing of drill cuttings according to one embodiment of the invention; 
           [0011]      FIG. 2  is a flow chart illustrating steps for disposing of drill cuttings according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]      FIG. 1  is a schematic view of a system of disposing of drill cuttings  10  according to one embodiment of the invention. While an onshore well drilling system  10  is described, it is also contemplated that the system and method of disposing of drill cuttings described herein could be used in conjunction with any other drilling system. The well drilling system  10  includes a drill rig  12  supporting a drill string  15 . A drill bit  20  is connected to the drill string at a lower end and used to cut into a mineral formation below the surface. A casing  25  surrounds the drill string  15 , and an annular area  22  is provided between the drill string  15  and the casing  25 . Drilling mud, which may comprise liquid or both liquid and solids, is pumped through the drill string  15  and through the drill bit  20  as the drill bit  20  rotates and cuts through the formation. As a result of this drilling operation, drill cuttings from the formation are produced. The drilling mud being pumped through the drill string  15  and through the drill bit  20  carries the drill cuttings up the annular area  22  to the surface. The drilling mud with drill cuttings is collected at the surface, and then transferred to one or more rig shakers  60 , typically by a conduit  30 . 
         [0013]    The rig shakers  60  include a screen with a basin beneath the screen to collect liquid as it is removed and filtered from the drilling mud with drill cuttings. The rig shakers  60  further include a vibrator for shaking the screen. As the vibrator shakes the screen, additional liquid is removed from the drilling mud and drill cuttings, and the liquid moves to the basin. In one embodiment, the rig shakers are mounted onto rig mud tanks  140 , and the liquid removed from the drilling mud and drill cuttings may be allowed to directly filter into the rig mud tanks  140 . The drilling mud with drill cuttings remaining on the screen of the rig shakers  60 , which will be referred to herein as the first filtered drilling mud, is moved to a discharge chute of the rig shakers  60 . The discharge chute of the rig shakers  60  may transfer the first filtered drilling mud directly onto one or more second shakers  70 , or a conduit  65  may carry the first filtered drilling mud from the rig shakers  60  to the second shakers  70 . Although the drilling mud with drill cuttings is described as being circulated through the rig shakers  60 , as is well known in the art, other first filtration methods and apparatus may be used to provide the first filtered drilling mud to the second shakers  70 . 
         [0014]    In one embodiment, the second shakers  70  may include high gravity shakers, and may include a finer gauge mesh screen (than the rig shakers  60 ) positioned over a basin for collecting liquid. The second shakers  70  are capable of removing and filtering additional liquid from the first filtered drilling mud, and may isolate the drill cuttings from the first filtered drilling mud. Like the rig shakers  60 , the second shakers  70  include a vibrator for shaking the screen, and hence, the liquid in the first filtered drilling mud is removed and filtered into the basin below the screen. The second shakers  70  also include a discharge chute, and as the liquid is removed from the first filtered drilling mud, the remaining drill cuttings and other solids, hereinafter referred to as the remaining drill cuttings, may be moved to the discharge chute of the second shakers  70 . The discharge chute allows the remaining drill cuttings to be collected in a collection area, which in one embodiment includes a common low point to facilitate the drill cuttings being directed to one general location. In one embodiment, instead of the remaining drill cuttings moving to the discharge chute of the second shakers  70 , the remaining drill cuttings are directly deposited to the collection area. 
         [0015]    It is contemplated that the second shakers  70  may include other drying cuttings technology, such as Verti-G or cyclone-type technology. For example, the first filtered drilling mud could be spun until the remaining drill cuttings are separated from the liquid, and the remaining drill cuttings are moved to a discharge chute that moves the remaining drill cuttings to a collection area. 
         [0016]    A vacuum conduit  72  is positioned within the collection area, and in one embodiment is positioned in or near the low point of the collection area. The vacuum conduit  72  also extends to and is connected to at least one container  85 A. The container  85 A is further connected to a vacuum pump conduit  95  that is connected to a vacuum pump  100 . The vacuum pump  100  creates suction within the container  85 A, and therefore within the vacuum conduit  72 , which results in the remaining drill cuttings being transferred to the container  85 A through the vacuum conduit  72 . An exemplary vacuum pump  100  includes a Triton 1500 Electric Vacuum Pump Skid. The container  85 A is an enclosed container and is capable of withstanding suction pressure created by the vacuum pump  100 , and is commonly referred to as a vacuum container by those skilled in the art. 
         [0017]    In one embodiment, the vacuum conduit  72  may extend to a manifold  75  wherein one or more secondary vacuum conduits  80 A,  80 B may extend to one or more containers  85 A,  85 B. In  FIG. 1 , only two secondary vacuum conduits  80 A,  80 B and containers  85 A,  85 B are shown, but it is contemplated that any number of secondary vacuum conduits and containers could be used. The manifold  75  may allow the one or multiple containers  85 A,  85 B to be filled with drill cuttings at a given time by adjusting the position of one or more valves located within the manifold. 
         [0018]    In one embodiment, the vacuum pump conduit  95  may be connected to a vacuum manifold  92  which may allow one or more secondary vacuum pump conduits  90 A,  90 B to extend to the containers  85 A,  85 B. In  FIG. 1 , only two secondary vacuum pump conduits  90 A,  90 B are shown, but it is contemplated that any number of secondary vacuum conduits could be used. The vacuum manifold  92  may allow the one or multiple containers  85 A,  85 B to be provided with suction from the vacuum pump  100  at a given time by adjusting the position of one or more valves located within the manifold. In one embodiment, a single manifold may be used to control vacuum suction within secondary vacuum conduits  80 A,  80 B and to control vacuum return within vacuum pump conduits  90 A,  90 B. 
         [0019]    After the drill cuttings are vacuumed into one or more of the containers  85 A,  85 B, the containers  85 A,  85 B may be removed and/or replaced by other like containers. The containers  85 A,  85 B may be hauled by truck or other transportation, and the drill cuttings contained therein may be recycled or disposed of in a controlled manner. 
         [0020]    Optionally, in one embodiment, a liquid conduit  110 A may extend from the second shakers  70  to the rig mud tank  140 , wherein liquid removed from the first filtered drilling mud may be transferred to the rig mud tank  140 . A pump, such as a submersible pump, may be used to move the liquid from the second shakers  70  to the rig mud tank  140 . Optionally, in one embodiment, a liquid conduit  110 B may extend from the second shakers  70  to one or more centrifuges  130 , wherein the liquid is processed further to remove excess particulates and impurities. A pump may also be used to move the liquid from the second shakers  70  to the centrifuges  130 . In one embodiment, the liquid processed by the centrifuges  130  may then be transferred to the rig mud tank  140  by a conduit  145 A. Furthermore, liquid in the rig mud tank  140  may be transferred by a conduit  145 B to the centrifuges  130  for processing, and then moved back to a separate compartment in the rig mud tank  140  via the conduit  145 A. 
         [0021]    In one embodiment, one or more of the second shakers  70  and/or the vacuum pump  100  may be positioned on a bin  105 , and in some instances, may be mounted on the bin  105 . In one embodiment, the bin is a low wall shale bin. The bin  105  may provide secondary containment to the second shakers  70  and/or the vacuum pump  100 , and the bin  105  may also provide easy transportation for the components contained therein. The bin  105 , along with the components therein, may be hauled by truck or other transportation from work site to work site, facilitating ease of the transfer of a large portion of the system for disposing drill cuttings described above. 
         [0022]      FIG. 2  is a flow chart illustrating steps of a method  200  for disposing drill cuttings according to one embodiment of the invention. In a first step  210 , drilling mud carrying drill cuttings is collected from a well drilling system  10 . The drilling mud carrying drill cuttings is transferred to one or more rig shakers  60 . In a second step  220 , liquid is removed from the drilling mud carrying drill cuttings by the rig shakers  60 , which leaves a first filtered drilling mud. The first filtered drilling mud is transferred to one or more second shakers  70 . In a third step  230 , liquid is removed from the first filtered drilling mud, which leaves drill cuttings. In a fourth step  240 , the drill cuttings are transferred to one or more containers  85 A,  85 B by a vacuum pump  100 . Optionally, in a fifth step  250 , the containers  85 A,  85 B filled with drill cuttings may be removed from the work site. In addition, the liquid removed during the first and second steps  220 ,  230  may optionally be transferred to one or more centrifuges  130 , wherein the liquid is processed in a sixth step  260 . Liquid from the rig shakers  60 , second shakers  70 , or centrifuges  130  may be collected in a rig mud tank  140 . 
         [0023]    While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.