Abstract:
A new method and device for separation of drilling cuttings from liquids and gases in air and fluid drilling operations. A liquid seal is created and maintained for proper separation of gas and liquid from cuttings and drilling slurry in air and liquid drilling. A cuttings agitation chamber is created and maintained under the liquid seal. Cuttings and particulates enter a separation vessel and fall towards the agitation chamber beneath the liquid seal and may be guided towards the agitation chamber and liquid seal by baffles or spray. Cuttings and particulates are kept in motion by nozzles in the agitation chamber for removal from the separation vessel through a discharge outlet. Outflow through the discharge outlet may be increased by a jet. The gases released from the drilling liquid exit the separation vessel through a gas outlet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. application Ser. No. 62/199,596 filed Jul. 31, 2015, and entitled “SEPARATING DRILLING CUTTINGS AND GAS USING A LIQUID SEAL,” which is hereby incorporated by reference herein in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    This specification relates generally to separation of drilling cuttings from liquids and gases in air and fluid drilling operations. 
       BACKGROUND 
       [0003]    Drill fluid generally includes one or more of hydrocarbons, water, salt, or other chemicals or substances and is widely used in oil and natural gas drilling operations. Drill fluid may provide subsurface pressure that aids in the prevention of underground fluids from entering the borehole, it lubricates and cools the drill bit, and it carries ground up earth including shale (which may be generally referred to herein as drill cuttings solids, or cuttings), in suspension, back to the surface so that it does not interfere with drilling operations. Typically, drill fluid is injected from the surface during the drilling process down through an annular channel within the drill string. The drill fluid then exits the drill string through nozzles or apertures in the drill bit where it thereafter returns to the surface in the area between the drill string and the walls of the borehole, carrying with it the drill cuttings so that they are removed from the borehole. Various mechanical means have been proposed for separating cuttings from gas or liquid during drilling operations, and for discharging the cuttings, including discharging them into a collection pit or hauloff container. 
         [0004]    Mist drilling is air drilling with liquid. The liquid can be water, soap, surfactants, or other chemicals. A water and soap mixture may be added to an air stream at the drilling surface at a controlled rate to improve annular hole cleaning. Many different mediums can be used for mist drilling (water, surfactants, etc.). The annular pressure increases in mist drilling, so the rate of penetration will usually be lower than in dust drilling. In mist drilling, the rate of penetration is often higher than in conventional mud drilling, which often means more cuttings to be disposed of per period of drilling. In mist drilling, drilling can proceed while producing fluids, hole cleaning capacity improves, risk of downhole fires decreases, and no nitrogen is needed. Air, mist, and fluid drilling operations typically require different dedicated-purpose gas-cuttings separators. Separators also vent gas at a safe distance from the wellbore. Inadequate separation of gas and cuttings can give rise to significant safety risks, including worker exposure to hazardous gases, and even flash fires at downstream cuttings collection stations. Accordingly, improvements are sought in enhanced separation of gases and cuttings in drilling operations to address these problems. 
       SUMMARY 
       [0005]    The novel devices and methods illustrated and described here provide enhanced separation of gas and liquids from cuttings during air, mist, or fluid drilling operations through creation, maintenance and use of a liquid seal. The separation of cuttings, gases, and fluids is preferably aided by one or more of a series of baffles, agitators, and liquid level controls. The liquid seal described and illustrated here allows for use of a single class of separators for drilling operations, including air, mist, and fluid drilling operations. The novel devices and methods illustrated and described significantly reduce the amount of dust and mist discharged through the gas outlets of a separation vessel. The novel devices and methods illustrated and described also significantly reduce the amount of liquid associated with the cuttings separated from the gas, liquid, or cuttings slurry. 
         [0006]    A liquid seal helps to ensure proper separation of gas and liquid from cuttings. The liquid seal helps enhance gas separation and improves conveyance of cuttings from the separator. Proper separation of gas and cuttings increases the safety of handling collected cuttings downstream. The novel equipment and method allows for more complete separation of liquid from cuttings and a significantly drier recovery of cuttings. Drier cuttings can result in cost savings and reduced environmental impact from decreased need of materials such as fly ash, wood shavings, or Power Pellets (™ Martlin Distributing www.martlindistributing.com) being used to solidify and manage cuttings and other liquid waste streams generated on a well site. 
         [0007]    In some embodiments, the liquid seal is maintained at least in part by control of one or more circulation pump. The liquid seal is provided in a volume of the separation vessel substantially above a volume for agitating cuttings. In some embodiments, the cuttings agitation chamber includes one or more agitators that help assure suspension of cuttings in a slurry during outflow from the separator. The agitators may include one or more mixing nozzles supplied with pressurized liquid. In some embodiments, agitators may include one or more mixing members as befits the particular use and installation. 
         [0008]    In some embodiments, discharge from the bottom of an agitation chamber of the cuttings slurry is aided by operation of a pressurized jet into the discharge line. Operation of a pressurized jet creates a low pressure region at the outlet of the agitation chamber. 
         [0009]    In some embodiments, cuttings are directed into an agitation chamber by a centering baffle configured to centralize cuttings over the agitation chamber or cuttings discharge region. The centering baffle can be used to direct cuttings into the center of the separation vessel to create a swirling flow by the mixing influence of fluid streams from nozzles. A drill fluid liquid outlet line provides a passage out of the agitation chamber and out of the separation vessel. In some embodiments, a drill fluid liquid outlet line syphons liquids from below the mixing nozzles. These embodiments may be used in conjunction with the embodiments summarized above and below. 
         [0010]    In some embodiments, a sprayer or a series of baffles, which can be used together, within the separation vessel further reduce escape of fine particulates in the gas outflow and effectively transfer particulates from the upward air flow to the downward liquid flow. In some embodiments, a sprayer is configured as a spray bar directed toward the surface of the liquid seal above the inlet of air cuttings into the separator vessel. In some embodiments, baffles above the inlet of air cuttings direct respective air, liquid, and cuttings flows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    A more complete understanding of the present disclosure may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numerals refer to similar elements throughout the Figures, and: 
           [0012]      FIG. 1  illustrates a separator vessel having a liquid seal for air, mist, and fluid drilling operations according to one embodiment; 
           [0013]      FIG. 2  illustrates a liquid seal and agitation chamber within a separator vessel according to one embodiment; 
           [0014]      FIG. 3  illustrates a controls diagram for use in maintaining a liquid seal fluid level in the separation vessel according to one embodiment; 
           [0015]      FIG. 4  illustrates a cross-sectional view of one embodiment of a centering baffle in a separator vessel having a liquid seal; 
           [0016]      FIG. 5  illustrates a cross-sectional view of baffles within the upper space of a separator vessel having a liquid seal in yet another embodiment; and 
           [0017]      FIG. 6 . illustrates an embodiment of the novel separation vessel with liquid seal in an oil and gas drilling operation. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The following description is of exemplary embodiments, but is not intended to limit the scope, applicability, or configuration of the claimed devices or methods. Rather, the following merely describes and enables the various described embodiments of the claimed devices and methods. Various changes may be made in the function and arrangement of the elements described without departing from the scope of the disclosure. It will be appreciated that the description herein may be adapted to be employed with alternatively configured devices having different arrangements, shapes, components, agitation mechanisms, baffles, chambers, nozzles, pumps, inlets, outlets, controls, and the like and still fall within the scope of the appended claims. It will also be appreciated that it is the intent behind providing examples of multiple embodiments of various aspects of the devices and methods that one aspect of one embodiment can work with other aspects of other embodiments. Thus, the detailed description that follows is for illustration not limitation. 
         [0019]    The separation devices, systems, and methods described herein manage drill cuttings, fluids, and gases during air, mist, or fluid drilling operations. Such drilling methods previously required two separate classes of separator equipment. 
         [0020]    As illustrated in  FIGS. 1, 2, and 3 , separator vessel  10  is charged with liquid, typically water to a predetermined level referred to as the process level  12  that is maintained preferably between a high level  14  and a low level  16 . Level controls may be operated from a control panel  18  and may include programmable logic controllers (“PLC”)  20  or variable frequency drives (“VFD”)  22 , and pumps. Pumps may include discharge pumps  24 , spare pumps  26 , and circulation pumps  28 . The liquid seal created in separation vessel  10 , in one preferred embodiment, is above cuttings discharge tube  30  having outlet  31  and intake  32 . Discharge tube  30  drains agitation chamber  42 . In some embodiments, this liquid is continually circulated in and out of separator vessel  10  in a closed loop with a discharge pump  24  that also maintains the fluid level of the liquid seal at or near process level  12 . Separation vessel  10  may include as an alternative embodiment a chevron  52  to help remove dust or moisture from the air or gases prior to exiting one or more gas outlet  48 . 
         [0021]    Separator vessel  10  receives drill cuttings from a drilling rig through air cuttings inlet  34 , and the drilling fluid (mud, gas, slurry) through one or more mud, gas, slurry (MGS) inlets  36 . As illustrated in  FIGS. 1, 2, 4, and 5 , drill cuttings are forced downward by downward baffles  38 ,  38 ′, and  38 ″ in one preferred embodiment. Fluid and cuttings are also directed by center baffle  40  to the center of separator vessel  10  into an agitation chamber  42 , which is defined by the approximate area between the bottom wall  44  of separator vessel  10  and the liquid seal preferably placed at approximately process level  12 . In this process, air is forced upward, around downward baffles  38 ,  38 ′, and  38 ″, one or spray bar  46 , and out of separation vessel  10  though an air outlet  48 . One or more sprayers  46  are placed to wet small solid particulates to prevent them from being carried upward and out of the vessel through air outlet  48 . In the embodiment of  FIG. 1 , sprayer  46  is configured as a spray bar. Sprayer  46  may also add any suitable chemical, e.g., defoamer, surfactant, that may be required or desired. 
         [0022]    Solids, including wetted particulates, are prevented from settling in the bottom of separation vessel  10  by operation of mixing nozzles  50 ,  50 ′ that keep solids substantially moving at all times. Wetted particulates fall into the liquid at the bottom of separation vessel  10  and are discharged. In one preferred embodiment, the solids are jetted and pumped out of separation vessel  10  by aid of a jetting nozzle  64  (as illustrated in  FIG. 6 ) charged by discharge pump  24 . Solids and liquids are removed from separation vessel  10  by pumping liquid to send the solids and liquids to a diffuser or other equipment (as illustrated in  FIG. 6 ). Liquid is recirculated back into separation vessel  10  through mixing nozzles  50 ,  50 ′ and sprayer  46 ; this cycle is typically continuous during operation of separator vessel  10 . 
         [0023]    With continued reference to  FIG. 1 , separator vessel  10  includes downward baffles  38 ,  38 ′, and  38 ″, one or sprayer  46 , a gas outlet  48 , and agitation chamber  42 . Separator vessel  10  creates a liquid seal proximate to process level  12 . The liquid seal separates cuttings and gases in both air drilling and fluid drilling operations by controlling inflow and outflow of liquids. In one embodiment, during fluid drilling, the fluid and cuttings enter into separation vessel  10  by MGS inlet  36 . Fluid is forced across downward baffles  38 ,  38 ′, and  38 ″. The fluid and cuttings in one preferred embodiment spread across downward baffles  38 ,  38 ′, and  38 ″ so that entrapped gases can escape and flow up and out of separator vessel  10 . The solids and fluid flow down to the bottom of separation vessel  10  and fill the vessel to approximately process level  12  below which is preferably positioned above discard tube  30 . The liquids and cuttings are forced into centering baffle  40  and above outlet  31  and inlet  32  of discharge tube  30 . The liquid level is maintained as illustrated in  FIGS. 1, 2, and 6  at approximately the height of process level  12  so as to maintain a downward pressure on outlet  31  of discharge tube  30 . Fluids and cuttings can be agitated in separation vessel  10 , in one preferred embodiment, by the use of mixing nozzles  50 ,  50 ′ to which fluid is pumped. One additional purpose of pumping drilling fluid is to keep the system from becoming clogged. 
         [0024]    With reference now to  FIG. 2 , a liquid seal approximately at process level  12  is shown at a level in separation vessel  10  slightly lower than the top rim edge  41  of centering baffle  40  and agitation chamber  42 . In this embodiment, agitation chamber  42  includes mixing nozzles  50 ,  50 ′ configured to agitate cuttings with a swirling action (depicted by counter current arrows) to prevent settling of solids and to enhance flowability of the suspension of solids exiting discharge tube  30  of separator vessel  10 . Discharge tube  30  and discharge tube outlet  31  are positioned and configured to convey liquid from agitation chamber  42  and to help maintain the fluid level of the liquid seal atop agitation chamber  42  at approximately process level  12 . In one preferred embodiment, outlet  31  of discharge tube  30  is above inlet  32  of discharge tube  30  as shown. A liquid seal is maintained by controlling the level of fluid above discharge tube  30 . 
         [0025]    With reference now to  FIGS. 3 and 4 , the liquid seal level, according to one embodiment, is maintained at approximately process level  12  by control of one or more pumps, in particular discharge pumps  24  alone or in conjunction with circulation pumps  28  in response to detection of fluid levels by level sensors including low low level sensor  56 , low level sensor  58 , process level sensor  60 , and high level sensor  62 . Other and different sensors may be included to meet the needs of the particular installation. In the illustrated embodiments, variable frequency drive  22  makes discharge pump  24  a variable discharge pump. Control panel  18  controls the outflow of fluids bearing solids from the bottom of agitation chamber  42 . The speed of one or more variable discharge pump is controlled to maintain the level of the liquid seal atop agitation chamber  42  in accordance with input from process level sensor  60 , or from high level sensor  62  and low level sensors  56 , or  58 . Additional sensors can provide greater resolution of liquid levels and greater levels of pump control. Suitable sensors include mechanical sensors, harmonic sensors, or other electronic sensors, or switches configured to generate an output signal in response to the presence or absence of a fluid. Fluid level sensors  56 ,  58 ,  60 ,  62  are coupled to a controller  18  for controlling at least a discharge pump  24 . Liquid level sensors  56 ,  58 , 60 ,  62  can alternatively be used to control other pumps, including circulation pump  28 , and to detect operational anomalies and to inform operators by triggering an alert, e.g., an audible or visual warning alert, or to inform upstream and downstream operators and equipment controls. 
         [0026]    Turning now to  FIGS. 3 and 6 , circulation pump  28  provides pressurized fluid to the mixing nozzles  50 ,  50 ′, sprayer  46 , and discharge jet  64 . In some embodiments, a single circulation pump can serve three high-pressure fluid delivery mechanisms. One or more additional pumps  26  can also be provided. Mixing nozzles  50 ,  50 ′ agitate cuttings in agitation chamber  42  to enhance flow of suspended cuttings. In one preferred embodiment ( FIG. 6 ), discharge jet  64  enters separation vessel  10  from below to help ensure continued flow of solids through discharge tube  30 . Solid cuttings exit agitation chamber  42  to one or more cuttings collectors (represented in  FIG. 6  as discharge tanks and shaker tanks). In some embodiments, one or more circulation pump  28  operates at a fixed rotational speed and operating pressure while the discharge pump  24  operates at variables speeds to maintain the desired liquid seal fluid level. In some cases, the circulation pump  28  can also be operated at variable speeds and be controlled in maintaining a desired liquid seal fluid level. Nozzles  50 ,  50 ′ agitating the swirling of cuttings in agitation chamber  42  can be adjusted for flow rate and swirl pattern. 
         [0027]    With reference now to  FIGS. 1, 2, 5, and 6 , centering baffle  40  concentrates and directs cuttings towards the center of agitation chamber  42  for maximum agitation there by mixing nozzles  50 ,  50 ′. An upper splash baffle  38 ″ also helps to direct liquids and cuttings downward as they enter separator vessel  10 . More than one baffle  38 ,  38 ′, and  38 ″ can help direct cuttings downward and help prevent the upward movement of cuttings and particulates towards air outlet  48 . In alternative embodiments, there may be a plurality of baffles  38 ,  38 ′, and  38 ″ of a variety of sizes, shapes, and downward angles. 
         [0028]    During the operation of separator vessel  10 , cuttings, gas, and the drilling air stream or drilling fluid stream enter separator vessel  10 . A series of baffles  38 ,  38 ′,  38 ″ divert solids and liquids downward towards agitation chamber  42  while allowing gas to rise upward towards one or more gas outlet  48 . Operation of separation vessel  10  creates a reservoir of liquid, also referred to as a liquid seal, that is preferably maintained at approximately the lower end of separator vessel  10  to maximize separation of gases above from solids below. The liquid seal helps insure that the gas and air passing out of one or more gas outlet  48  is cleaned of particulates. The liquid seal also helps insure that the outflow of fluids and cuttings from discharge tube  30  contains significantly less fluid that was previously possible. Agitation of the solids within agitation chamber  42 , by mixing nozzles  50 ,  50 ′ or other means, mechanical, hydraulic, electro-mechanical, passive, or active helps maintain flowability of solids and helps release entrained gases prior to discharge of cuttings. 
         [0029]    The liquid seal fluid level is created and then is maintained at approximately process level  12  through manipulation of discharge pump speeds in response to detection of fluid levels by various sensors. Maintenance of the fluid level is further controlled by inflow of fluid into the system and by one or more discharge pumps  24  and circulation pumps  28  supplying mixing nozzles  50 ,  50 ′, discharge line jet  64 , and sprayers  46 . The discharge pump can in one embodiment provide a closed loop recirculation of liquids. Closed loop recirculation reduces water consumption. 
         [0030]    The novel liquid seal system and method provides increased safety through reduction of flammable and otherwise hazardous gases that otherwise would accompany discharge of solids from a separator vessel. Drier cuttings can result in cost savings and reduced environmental impact. The system and method of the novel fluid seal in separator vessel  10  disclosed herein also saves significant time, cost, and footprint during shipping, installation, operation, maintenance, and relocation of separator vessel  10  and related equipment. 
         [0031]    Accordingly, the novel liquid seal system and method using separator vessel  10  accommodates enhanced separation of gases and cuttings in both air drilling and fluid drilling operations. Separator vessel  10 , baffles  38 ,  38 ′, and  38 ″ and other structural components may be constructed of metal, carbon fiber, composite or other material suitable for the intended operations. Similarly, while the present fluid seal system and method has been described herein for use in air drilling and fluid drilling operations, it may be readily used in any number of other industrial applications and with any number of other drilling equipment or other similar devices now known or hereafter developed. 
         [0032]    Finally, while the fluid seal system and method has been described with reference to various exemplary embodiments, many changes, combinations and modifications may be made to the exemplary embodiments without departing from the scope of the accompanying claims. For example, the various components may be implemented in alternative ways and the various embodiments may be used with other embodiments. These alternatives can be suitably selected depending upon the particular application or in consideration of any number of factors associated with the operation of the device. In addition, the techniques described herein may be extended or modified for use with other types of devices. These and other changes or modifications are intended to be included within the scope of this disclosure.