CA2194801A1 - Separator and method for separating components of pressurized drilling fluid returns - Google Patents
Separator and method for separating components of pressurized drilling fluid returnsInfo
- Publication number
- CA2194801A1 CA2194801A1 CA002194801A CA2194801A CA2194801A1 CA 2194801 A1 CA2194801 A1 CA 2194801A1 CA 002194801 A CA002194801 A CA 002194801A CA 2194801 A CA2194801 A CA 2194801A CA 2194801 A1 CA2194801 A1 CA 2194801A1
- Authority
- CA
- Canada
- Prior art keywords
- vessel
- vortex
- solids
- liquid
- gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000005553 drilling Methods 0.000 title claims abstract description 34
- 239000012530 fluid Substances 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims description 8
- 239000007788 liquid Substances 0.000 claims abstract description 57
- 239000007787 solid Substances 0.000 claims abstract description 48
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 17
- 238000000926 separation method Methods 0.000 claims abstract description 10
- 230000005484 gravity Effects 0.000 claims abstract description 8
- 239000007789 gas Substances 0.000 claims description 45
- 238000007599 discharging Methods 0.000 claims description 14
- 230000002093 peripheral effect Effects 0.000 claims description 13
- 229930195733 hydrocarbon Natural products 0.000 claims description 10
- 150000002430 hydrocarbons Chemical class 0.000 claims description 10
- 238000005520 cutting process Methods 0.000 claims description 7
- 239000004215 Carbon black (E152) Substances 0.000 claims description 4
- 239000002002 slurry Substances 0.000 abstract description 6
- 230000015572 biosynthetic process Effects 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 235000008504 concentrate Nutrition 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 230000003467 diminishing effect Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 235000014666 liquid concentrate Nutrition 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000009491 slugging Methods 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D19/00—Degasification of liquids
- B01D19/0042—Degasification of liquids modifying the liquid flow
- B01D19/0052—Degasification of liquids modifying the liquid flow in rotating vessels, vessels containing movable parts or in which centrifugal movement is caused
- B01D19/0057—Degasification of liquids modifying the liquid flow in rotating vessels, vessels containing movable parts or in which centrifugal movement is caused the centrifugal movement being caused by a vortex, e.g. using a cyclone, or by a tangential inlet
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/34—Arrangements for separating materials produced by the well
- E21B43/35—Arrangements for separating materials produced by the well specially adapted for separating solids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D19/00—Degasification of liquids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/24—Feed or discharge mechanisms for settling tanks
- B01D21/2405—Feed mechanisms for settling tanks
- B01D21/2411—Feed mechanisms for settling tanks having a tangential inlet
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/24—Feed or discharge mechanisms for settling tanks
- B01D21/2494—Feed or discharge mechanisms for settling tanks provided with means for the removal of gas, e.g. noxious gas, air
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/26—Separation of sediment aided by centrifugal force or centripetal force
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/26—Separation of sediment aided by centrifugal force or centripetal force
- B01D21/267—Separation of sediment aided by centrifugal force or centripetal force by using a cyclone
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
- B04C3/00—Apparatus in which the axial direction of the vortex flow following a screw-thread type line remains unchanged ; Devices in which one of the two discharge ducts returns centrally through the vortex chamber, a reverse-flow vortex being prevented by bulkheads in the central discharge duct
- B04C3/04—Multiple arrangement thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
- B04C5/00—Apparatus in which the axial direction of the vortex is reversed
- B04C5/08—Vortex chamber constructions
- B04C5/103—Bodies or members, e.g. bulkheads, guides, in the vortex chamber
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
- B04C5/00—Apparatus in which the axial direction of the vortex is reversed
- B04C5/12—Construction of the overflow ducting, e.g. diffusing or spiral exits
- B04C5/13—Construction of the overflow ducting, e.g. diffusing or spiral exits formed as a vortex finder and extending into the vortex chamber; Discharge from vortex finder otherwise than at the top of the cyclone; Devices for controlling the overflow
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
- B04C5/00—Apparatus in which the axial direction of the vortex is reversed
- B04C5/14—Construction of the underflow ducting; Apex constructions; Discharge arrangements ; discharge through sidewall provided with a few slits or perforations
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/06—Arrangements for treating drilling fluids outside the borehole
- E21B21/063—Arrangements for treating drilling fluids outside the borehole by separating components
- E21B21/065—Separating solids from drilling fluids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2221/00—Applications of separation devices
- B01D2221/04—Separation devices for treating liquids from earth drilling, mining
Abstract
The separator comprises a vertical cylindrical pressure vessel having elliptical top and bottom heads. A mechanical means, referred to as a vortex tube cluster of vertical tubes, is mounted in the upper section of the vessel chamber, spaced above the bottom head to define a lower chamber section for fluid and solids separation. Pressurized drilling fluid returns are directed tangentially into the vortex tubes and a subsequent centrifugal action is generated. Contained gas separates and forms a gas vortex which exits upwardly from the vortex tubes and vessel top. The liquids and solids discharge into the vessel lower chamber section where solids settle by gravity to the bottom. The solids are withdrawn from the base of the vessel by a slurry pump. The oil and water components of the fluid layer also separate by gravity and are individually removed from the vessel.
Description
FIELD OF THE INVENTION
2 The invention relates to a pressure vessel separator for continuously 3 separating the liquid, solid and gas components of pressurized drilling fluid returns, 4 produced from a well undergoing drilling. The separator utilizes a mechanical device, that creates centrifugal action to firstly separate the gas and solids from the liquid, 6 followed by gravity separation under quiescent conditions to separate liquid 7 hydrocarbons from watèr. The solids, gases, liquid hydrocarbons and water are 8 independently removed from the separator. The invention also relates to the method 9 practised.
BACKGROUND OF THE INVENTION
11 The invention is an improvement of a prior art separator and method 12 described in United States Patent No. 5,415,776 (Homan).
13 This prior art separator is used to separate the components of 14 pressurized drilling fluids returning from a well undergoing drilling, usually "underbalanced" or "multiphase flow" drilling.
16 Underbalanced drilling involves lightening drilling fluid (such as water or 17 diesel oil) with a gas (typically nitrogen). This is done so that the column of lightened 18 drilling fluid in the wellbore exerts a bottom hole pressure that is less than the pressure 19 in the formation being drilled. As a result, the drilling fluid does not invade the formation. If it were to do so, the well productivity could be adversely affected.
21 Underbalanced drilling of a well may cause reservoir liquids and gas to enter the 22 circulating drilling fluid. Furthermore, the drilling fluid is circulated under pressure. As 23 a result, the drilling fluid returns, leaving the wellbore, are under pressure and typically 2 1 ~48 0 1 comprise a mixture of solids, liquids and gases. The solids commonly comprise coarse 2 bit cuttings and "fines". The liquids can comprise the original drilling liquid as well as 3 formation or reservoir fluids. And the gases can include the lightening gas and 4 formation gas.
The drilling fluid returns, therefore, need to be handled with pressure-6 containing equipment. It is also necessary to separate the gases, liquids and solids 7 so that they are recovered as separate streams. The solids are removed. The gases 8 may be re-used or vented. And finally it is desirable to separate the hydrocarbons from 9 the balance of the liquid.
Pressure vessel separators for separating liquid/gas/solids components 11 of a stream have long been common in the oilfield equipment art. However, these prior 12 art separators are not adapted to process drilling fluid returns, which contain large 13 quantities of coarse bit cuttings and experience severe fluid slugging. Instead, drilling 14 fluid returns have almost entirely been processed using shale shakers and open mud tank systems, which would not be environmentally safe or sound especially in the16 presence of H2S gas. These systems are not capable of handling pressurized returns.
17 The previously mentioned Homan patent discloses a separator for 18 separating the components of pressurized drilling fluid returns. The separator involves:
19 ~ An elongate, horizontal, cylindrical pressure vessel having elliptical heads closing its ends. The commercial embodiment of 21 this vessel has a typical diameter of 8 feet and a length of 30 22 feet;
23 ~ A returns feed pipe extends into the vessel at its first end. The 24 feed pipe connects with an involute structure designed to reduce the velocity of the incoming feed before discharging it;
21 94~01 ~ A hopper-like compartment is located beneath the involute 2 structure, for receiving the incoming returns. The compartment3 is defined by the head, the vessel's curved sidewalls and a 4 slanted weir forming the downstream end of the compartment;
~ An outlet, at the base of the compartment, is connected with a 6 pump, for withdrawing of a solids slurry while drilling fluid 7 continues to enter the separator;
8 ~ The chamber downstream of the slanted weir is provided with 9 outlets at different elevations for removing gravity-separated water and liquid hydrocarbons; and 11 ~ The vessel has an overhead outlet for removing gases.
12 In operation, the coarse bit cuttings settle out by gravity in the inlet compartment and 13 are concentrated as they are funnelled down to the pump. Solids are removed from 14 the vessel without interfering with ongoing drilling and continuous production of drilling fluid returns. The gas breaks out and is removed for venting, flaring or re-using. The 16 liquid overflows the compartment weir and separates by gravity separation into 17 hydrocarbon and water layers. These liquids are individually removed through suitable 1 8 outlets.
19 The patented separator (developed by the present assignee) has been commercially successful. However there is on-going need to reduce the size of the 21 separator, both to reduce the vessel cost and transportability for smaller wellsites 22 and/or off-shore drilling platforms.
23 The present invention is directed to achieving these ends.
~! 9~801 SUMMARY OF THE INVENTION
2 In accordance with the preferred form of the present invention, there is 3 provided a separator comprising:
4 ~ A vertical cylindrical pressure vessel forming an internal chamber;
~ A tapered feed pipe extending into the upper end of the chamber, 6 for introducing pressurized drilling fluid returns;
7 ~ A cluster of vertical, cylindrical vortex tubes connected with the 8 feed pipe, with each tube having an inlet at its upper end. The 9 inlet is arranged so that returns are tangentially introduced into each tube. The tube has transverse top and bottom walls, the 11 top wall having a central opening for gas oufflow, the tube 12 sidewall having peripheral bottom openings for liquid and solids 1 3 oufflow;
14 ~ A vortex breaker plate is situated below the vortex tubes for stopping the gas vortex from reaching the fluid section;
16 ~ The vessel sidewall section, that extends down from the bottom 17 of the vortex tubes, and the curved bottom head together form a 18 lower chamber section;
19 ~ The solids settle out in the lower chamber section and are concentrated as they move to a central bottom outlet formed by 21 the head, the outlet being connected with a solids slurry 22 withdrawal pump. The liquid migrates upward; forming a liquid 23 layer in the vessel chamber;
~ The vessel sidewall has water and hydrocarbon outlets situated 2 above the bottom of the vortex tubes at different elevations.
3 These outlets serve to individually discharge oil and water into 4 discharge lines;
~ A transverse baffle is located above the vortex cluster tubes - the 6 gas flows upwardly and contacts the baffle, for removal of 7 entrained liquid in the gas;
8 ~ The vessel has an outlet, at its upper end, for discharging gases 9 into a gas line; and ~ The vessel has means, such as floats, for controlling the 11 discharge of water and hydrocarbons through their discharge 12 outlets, as well as to maintain pre-determined fluid levels.
13 In operation, the feed pipe delivers equal amounts of drilling fluid returns 14 at about the same velocity into each of the several vortex tubes forming the cluster.
15 The incoming fluid enters tangentially into each tube. A central gas vortex is formed, 16 which discharges upwardly out of the tube into the upper reaches of the vessel 17 chamber, impinging on a baffle. The gases are discharged through the gas outlet and 18 gas line. The solids concentrate as a downwardly moving, rotating layer pressing 19 against the inside surface of the tube. The liquid concentrates as a downward moving, 20 rotating layer between the solids and the gas. The solids and liquids contained inside 21 each vortex tube are forced downward to the bottom of the tube and are discharged 22 through the peripheral bottom openings. The bottom section of the tubes may have 23 a vortex breaker plate or a series of elbows to eliminate the vortex. In the lower 24 chamber section, the solids settle downward, concentrated by the curved head, and 25 are subsequently withdrawn by the slurry pump through the bottom outlet. The liquid 21 ~4~01 leaving the tubes collects and forms a separate layer external to the vortex cluster in 2 the chamber. This layer submerges the bottom of the vortex tubes and keeps the gas 3 vortex from reaching the discharged liquid. As a result, the solids and the liquid in the 4 vessel chamber remain relatively quiescent. This enables efficient separation of the liquid and solids. The liquid in the layer further separates into water and hydrocarbon 6 layers, which are individually removed.
7 It has been found that a much smaller sized vessel, in accordance with 8 the invention, will provide efficient separation comparable to the prior art horizontal 9 vessel.
In one broad aspect, the invention comprises a separator for separating 11 the liquid, solids and gas components of pressurized drilling fluid returns from a well 12 undergoing drilling, comprising: a vertical cylindrical pressure vessel having top and 13 bottom end walls and a side wall, said walls forming an internal chamber; a cluster of 14 vertical vortex tubes positioned within the chamber and located above the vessel's bottom end wall, so that a chamber bottom section extends below the bottom ends of 16 the vortex tubes; each vortex tube having a side wall forming a bore, said side wall 17 having an inlet at its upper end for tangentially introducing the returns into the bore, the 18 vortex tube being open at its upper end and closed by a transverse plate at its lower 19 end and having at least one peripheral opening at its lower end for discharging the liquid and solids; means for feeding returns to each vortex tube through its inlet; the 21 vessel bottom wall being elliptical and having a central outlet; means for withdrawing 22 solids through the vessel bottom wall outlet; outlet means for discharging gas from the 23 upper end of the vessel; and outlet means, located above the bottom ends of the 24 vortex tubes, for discharging hydrocarbons and water separately through the vessel side wall.
21 ~4801 In another broad aspect, the invention comprises a method for separating 2 the components of pressurized drilling fluid returns produced from a well undergoing 3 drilling, said fluid comprising bit cuttings, liquid, which may include produced oil, and 4 gas, comprising: providing a vertical pressure vessel having top, bottom and side 5 walls which form an internal chamber, said vessel containing at least one vertical 6 vortex tube having a top opening, a closed bottom end and a peripheral side opening 7 at its bottom end, said vessel having a returns feed pipe connected with the upper end 8 of the vortex tube for feeding returns tangentially to the inner surface of the vortex 9 tube, the bottom end of the vortex tube being spaced above the vessel bottom wall so 10 that the vessel chamber includes a bottom section between the vessel bottom wall and 11 the bottom end of the vortex tube, the vessel bottom wall having a central outlet at the 12 base thereof for solids removal, the vessel side wall having liquid discharge outlets 13 spaced above the bottom end of the vortex tube, the vessel having a gas outlet at its 14 upper end, said method comprising: feeding returns tangentially into the upper end of 15 the vortex tube so that they rotate downward through the tube bore and form a central 16 gas vortex, an outer layer of solids and an inner layer of liquid; discharging the gas 17 out of the upper end of the vortex tube and through the gas outlet; discharging liquid 18 and solids from the vortex tube through its peripheral opening into the chamber bottom 19 section and temporarily retaining them in the chamber so that they separate by gravity 20 separation under quiescent conditions to form a bottom layer of solids and an upper 21 layer of liquid; withdrawing solids through the vessel's bottom wall outlet while 22 maintaining the inflow of returns into the vessel; and discharging liquid through the 23 liquid discharge outlets at restricted rates so that the bottom outlet of the vortex tube 24 remains submerged.
DESCRIPTION OF THE DRAWING
2 Figure 1 is a side view of the separator, showing the internals in shadow 3 lines;
4 Figure 2 is a top view of the separator;
Figure 3 is a process schematic of the separator assembly, showing the 6 flow directions and discharge lines;
7 Figure 4 is a top plan view of the separator showing its discharge lines;
8 Figure 5 is a side view of the liquid discharge lines; and 9 Figure 6 is a bottom view showing the solids slurry removal assembly.
DESCRIPTION OF THE PREFERRED EMBODIMENT
11 The separator 1 comprises a vertical cylindrical pressure vessel 2 having 12 a side wall 3 and elliptical top and bottom heads 4,5. The vessel forms an internal 13 chamber 6.
14 A known vortex tube cluster assembly 7 is mounted in the chamber 6.
This assembly is available from Porta-Test International Inc., Edmonton, Alberta.
16 The assembly 7 comprises a tapered feed pipe 8 and one or more 17 vertical vortex tubes 9 connected thereto. Each vortex tube has an inlet 10 at its upper 18 end which communicates with the bore 30 of the feed pipe 8. The connection of the 19 feed pipe 8 with each vortex tube inlet 10 is such that incoming returns are fed tangentially relative to the inner surface 11 of the vortex tube. The vortex tube 9 has 21 a transverse top wall 12 forming a central opening 13 for the release of the gas 22 component. The vortex tube also has a transverse bottom wall 14 closing its bottom 23 end. The vortex tube side wall 15 forms peripheral openings 16 at its bottom end for 24 the discharge of liquid and solids. T he tapered feed pipe 8 is designed to supply 21~4801 approximately equal amounts of returns to each vortex tube at about the same fluid 2 velocity.
3 A horizontal vortex breaker plate 14 is suspended from the bottom ends 4 of the vortex tubes 9 in close proximity to the peripheral openings 16. The breaker plate 14 extends laterally beyond the vortex tubes but is inwardly spaced from the 6 vessel side wall 3.
7 The bottoms of the vortex tubes 9 are spaced above the bottom head 5, 8 so as to form a lower section 20 of the chamber 6. The tops of the vortex tubes 9 are 9 spaced below the top head 4 to form an upper section 50 of the chamber 6.
A pair of liquid outlets 21, 22 extend through the vessel side wall 3 at 11 positions above the bottoms of the vortex tubes 9. The outlets 21, 22 are vertically 12 spaced apart whereby the lower outlet 21 is used to discharge water and the upper 13 outlet 22 discharges oil. A pair of openings 23, 24 are positioned above the liquid 14 outlets 21, 22 respectively. Conventional float assemblies 25, 26 are mounted in the openings 23, 24 to actuate conventional dump valves 27, 28 to maintain pre-16 determined liquid levels as well as to control the discharge of water and oil through 17 lines 29, 31 respectively.
18 The bottom head 5 forms a central outlet 32 which is connected to a 19 slurry pump 33 by a solids discharge line 34. The pump 33 is used to withdraw solids form the base of the separator under pressure while the inflow of the returns is21 continued.
22 Installed in the top head 4 is a central baffle deflector 38, against which 23 the gas impinges, to trap residual liquid droplets in the gas. The deflector 38 is 24 inwardly spaced from the vessel side wall 3. The gas discharges through outlet 36 which connects with a gas discharge line 37.
In operation, the incoming returns are tangentially introduced through 2 feed pipe 8 and inlets 10 into the bores 35 of the vortex tubes 9. Each vortex tube 3 receives about the same amount of returns moving at about the same velocity. In each 4 vortex tube, the returns stream components separate under the influence of centrifugal force to form: a central gas vortex, which reverses itself and exits upwardly through 6 the opening 13, across the baffle 38 and exits through outlet 36 and gas discharge line 7 37; an outer layer of solids which rotates downward through the vortex tube bore 35 8 and discharges through the vortex tube bottom peripheral openings 16; and an 9 intermediate layer of liquid located between the gas vortex and the solids layer, which also rotates downward through the vortex tube bore 35 and also discharges through 11 the bottom peripheral openings 16. In the chamber lower section 20, the solid bit 12 cuttings settle and separate from the liquid. The cuttings are concentrated as they 13 funnel through the diminishing cross-sectional area defined by the bottom head 5 and 14 are withdrawn from the chamber 6 by the pump 33 and are discharged through the line 37. The liquid collects as a separate layer in the chamber 6 above the solids layer.
16 Oil and water separate in this layer by gravity separation. The water and oil are 17 individually dumped through lines 29, 31 under the control of float assemblies 25, 26 18 and dump valves 27, 28. The layer or level of liquid in chamber 6 covers the vortex 19 tube peripheral openings 16 to provide an effective seal that prevents gas from escaping or blowing out of the vortex tube bottom openings.
21 The separation process in the separator is characterized by the following 22 advantages:
23 ~ the gas is efficiently separated in the vortex tubes, and is 24 removed as an upwardly moving stream, so that it does not create a turbulence that would disturb liquid and solids;
21 ~4801 ~ the solids and liquids separate efficiently in the chamber outside 2 the vortex tubes, under quiescent conditions;3 ~ there is improved efficiency of the separation process utilizing a 4 mechanical device (vortex cluster); and ~ due to these improved efficiencies, a smaller sized vessel can be 6 used.
BACKGROUND OF THE INVENTION
11 The invention is an improvement of a prior art separator and method 12 described in United States Patent No. 5,415,776 (Homan).
13 This prior art separator is used to separate the components of 14 pressurized drilling fluids returning from a well undergoing drilling, usually "underbalanced" or "multiphase flow" drilling.
16 Underbalanced drilling involves lightening drilling fluid (such as water or 17 diesel oil) with a gas (typically nitrogen). This is done so that the column of lightened 18 drilling fluid in the wellbore exerts a bottom hole pressure that is less than the pressure 19 in the formation being drilled. As a result, the drilling fluid does not invade the formation. If it were to do so, the well productivity could be adversely affected.
21 Underbalanced drilling of a well may cause reservoir liquids and gas to enter the 22 circulating drilling fluid. Furthermore, the drilling fluid is circulated under pressure. As 23 a result, the drilling fluid returns, leaving the wellbore, are under pressure and typically 2 1 ~48 0 1 comprise a mixture of solids, liquids and gases. The solids commonly comprise coarse 2 bit cuttings and "fines". The liquids can comprise the original drilling liquid as well as 3 formation or reservoir fluids. And the gases can include the lightening gas and 4 formation gas.
The drilling fluid returns, therefore, need to be handled with pressure-6 containing equipment. It is also necessary to separate the gases, liquids and solids 7 so that they are recovered as separate streams. The solids are removed. The gases 8 may be re-used or vented. And finally it is desirable to separate the hydrocarbons from 9 the balance of the liquid.
Pressure vessel separators for separating liquid/gas/solids components 11 of a stream have long been common in the oilfield equipment art. However, these prior 12 art separators are not adapted to process drilling fluid returns, which contain large 13 quantities of coarse bit cuttings and experience severe fluid slugging. Instead, drilling 14 fluid returns have almost entirely been processed using shale shakers and open mud tank systems, which would not be environmentally safe or sound especially in the16 presence of H2S gas. These systems are not capable of handling pressurized returns.
17 The previously mentioned Homan patent discloses a separator for 18 separating the components of pressurized drilling fluid returns. The separator involves:
19 ~ An elongate, horizontal, cylindrical pressure vessel having elliptical heads closing its ends. The commercial embodiment of 21 this vessel has a typical diameter of 8 feet and a length of 30 22 feet;
23 ~ A returns feed pipe extends into the vessel at its first end. The 24 feed pipe connects with an involute structure designed to reduce the velocity of the incoming feed before discharging it;
21 94~01 ~ A hopper-like compartment is located beneath the involute 2 structure, for receiving the incoming returns. The compartment3 is defined by the head, the vessel's curved sidewalls and a 4 slanted weir forming the downstream end of the compartment;
~ An outlet, at the base of the compartment, is connected with a 6 pump, for withdrawing of a solids slurry while drilling fluid 7 continues to enter the separator;
8 ~ The chamber downstream of the slanted weir is provided with 9 outlets at different elevations for removing gravity-separated water and liquid hydrocarbons; and 11 ~ The vessel has an overhead outlet for removing gases.
12 In operation, the coarse bit cuttings settle out by gravity in the inlet compartment and 13 are concentrated as they are funnelled down to the pump. Solids are removed from 14 the vessel without interfering with ongoing drilling and continuous production of drilling fluid returns. The gas breaks out and is removed for venting, flaring or re-using. The 16 liquid overflows the compartment weir and separates by gravity separation into 17 hydrocarbon and water layers. These liquids are individually removed through suitable 1 8 outlets.
19 The patented separator (developed by the present assignee) has been commercially successful. However there is on-going need to reduce the size of the 21 separator, both to reduce the vessel cost and transportability for smaller wellsites 22 and/or off-shore drilling platforms.
23 The present invention is directed to achieving these ends.
~! 9~801 SUMMARY OF THE INVENTION
2 In accordance with the preferred form of the present invention, there is 3 provided a separator comprising:
4 ~ A vertical cylindrical pressure vessel forming an internal chamber;
~ A tapered feed pipe extending into the upper end of the chamber, 6 for introducing pressurized drilling fluid returns;
7 ~ A cluster of vertical, cylindrical vortex tubes connected with the 8 feed pipe, with each tube having an inlet at its upper end. The 9 inlet is arranged so that returns are tangentially introduced into each tube. The tube has transverse top and bottom walls, the 11 top wall having a central opening for gas oufflow, the tube 12 sidewall having peripheral bottom openings for liquid and solids 1 3 oufflow;
14 ~ A vortex breaker plate is situated below the vortex tubes for stopping the gas vortex from reaching the fluid section;
16 ~ The vessel sidewall section, that extends down from the bottom 17 of the vortex tubes, and the curved bottom head together form a 18 lower chamber section;
19 ~ The solids settle out in the lower chamber section and are concentrated as they move to a central bottom outlet formed by 21 the head, the outlet being connected with a solids slurry 22 withdrawal pump. The liquid migrates upward; forming a liquid 23 layer in the vessel chamber;
~ The vessel sidewall has water and hydrocarbon outlets situated 2 above the bottom of the vortex tubes at different elevations.
3 These outlets serve to individually discharge oil and water into 4 discharge lines;
~ A transverse baffle is located above the vortex cluster tubes - the 6 gas flows upwardly and contacts the baffle, for removal of 7 entrained liquid in the gas;
8 ~ The vessel has an outlet, at its upper end, for discharging gases 9 into a gas line; and ~ The vessel has means, such as floats, for controlling the 11 discharge of water and hydrocarbons through their discharge 12 outlets, as well as to maintain pre-determined fluid levels.
13 In operation, the feed pipe delivers equal amounts of drilling fluid returns 14 at about the same velocity into each of the several vortex tubes forming the cluster.
15 The incoming fluid enters tangentially into each tube. A central gas vortex is formed, 16 which discharges upwardly out of the tube into the upper reaches of the vessel 17 chamber, impinging on a baffle. The gases are discharged through the gas outlet and 18 gas line. The solids concentrate as a downwardly moving, rotating layer pressing 19 against the inside surface of the tube. The liquid concentrates as a downward moving, 20 rotating layer between the solids and the gas. The solids and liquids contained inside 21 each vortex tube are forced downward to the bottom of the tube and are discharged 22 through the peripheral bottom openings. The bottom section of the tubes may have 23 a vortex breaker plate or a series of elbows to eliminate the vortex. In the lower 24 chamber section, the solids settle downward, concentrated by the curved head, and 25 are subsequently withdrawn by the slurry pump through the bottom outlet. The liquid 21 ~4~01 leaving the tubes collects and forms a separate layer external to the vortex cluster in 2 the chamber. This layer submerges the bottom of the vortex tubes and keeps the gas 3 vortex from reaching the discharged liquid. As a result, the solids and the liquid in the 4 vessel chamber remain relatively quiescent. This enables efficient separation of the liquid and solids. The liquid in the layer further separates into water and hydrocarbon 6 layers, which are individually removed.
7 It has been found that a much smaller sized vessel, in accordance with 8 the invention, will provide efficient separation comparable to the prior art horizontal 9 vessel.
In one broad aspect, the invention comprises a separator for separating 11 the liquid, solids and gas components of pressurized drilling fluid returns from a well 12 undergoing drilling, comprising: a vertical cylindrical pressure vessel having top and 13 bottom end walls and a side wall, said walls forming an internal chamber; a cluster of 14 vertical vortex tubes positioned within the chamber and located above the vessel's bottom end wall, so that a chamber bottom section extends below the bottom ends of 16 the vortex tubes; each vortex tube having a side wall forming a bore, said side wall 17 having an inlet at its upper end for tangentially introducing the returns into the bore, the 18 vortex tube being open at its upper end and closed by a transverse plate at its lower 19 end and having at least one peripheral opening at its lower end for discharging the liquid and solids; means for feeding returns to each vortex tube through its inlet; the 21 vessel bottom wall being elliptical and having a central outlet; means for withdrawing 22 solids through the vessel bottom wall outlet; outlet means for discharging gas from the 23 upper end of the vessel; and outlet means, located above the bottom ends of the 24 vortex tubes, for discharging hydrocarbons and water separately through the vessel side wall.
21 ~4801 In another broad aspect, the invention comprises a method for separating 2 the components of pressurized drilling fluid returns produced from a well undergoing 3 drilling, said fluid comprising bit cuttings, liquid, which may include produced oil, and 4 gas, comprising: providing a vertical pressure vessel having top, bottom and side 5 walls which form an internal chamber, said vessel containing at least one vertical 6 vortex tube having a top opening, a closed bottom end and a peripheral side opening 7 at its bottom end, said vessel having a returns feed pipe connected with the upper end 8 of the vortex tube for feeding returns tangentially to the inner surface of the vortex 9 tube, the bottom end of the vortex tube being spaced above the vessel bottom wall so 10 that the vessel chamber includes a bottom section between the vessel bottom wall and 11 the bottom end of the vortex tube, the vessel bottom wall having a central outlet at the 12 base thereof for solids removal, the vessel side wall having liquid discharge outlets 13 spaced above the bottom end of the vortex tube, the vessel having a gas outlet at its 14 upper end, said method comprising: feeding returns tangentially into the upper end of 15 the vortex tube so that they rotate downward through the tube bore and form a central 16 gas vortex, an outer layer of solids and an inner layer of liquid; discharging the gas 17 out of the upper end of the vortex tube and through the gas outlet; discharging liquid 18 and solids from the vortex tube through its peripheral opening into the chamber bottom 19 section and temporarily retaining them in the chamber so that they separate by gravity 20 separation under quiescent conditions to form a bottom layer of solids and an upper 21 layer of liquid; withdrawing solids through the vessel's bottom wall outlet while 22 maintaining the inflow of returns into the vessel; and discharging liquid through the 23 liquid discharge outlets at restricted rates so that the bottom outlet of the vortex tube 24 remains submerged.
DESCRIPTION OF THE DRAWING
2 Figure 1 is a side view of the separator, showing the internals in shadow 3 lines;
4 Figure 2 is a top view of the separator;
Figure 3 is a process schematic of the separator assembly, showing the 6 flow directions and discharge lines;
7 Figure 4 is a top plan view of the separator showing its discharge lines;
8 Figure 5 is a side view of the liquid discharge lines; and 9 Figure 6 is a bottom view showing the solids slurry removal assembly.
DESCRIPTION OF THE PREFERRED EMBODIMENT
11 The separator 1 comprises a vertical cylindrical pressure vessel 2 having 12 a side wall 3 and elliptical top and bottom heads 4,5. The vessel forms an internal 13 chamber 6.
14 A known vortex tube cluster assembly 7 is mounted in the chamber 6.
This assembly is available from Porta-Test International Inc., Edmonton, Alberta.
16 The assembly 7 comprises a tapered feed pipe 8 and one or more 17 vertical vortex tubes 9 connected thereto. Each vortex tube has an inlet 10 at its upper 18 end which communicates with the bore 30 of the feed pipe 8. The connection of the 19 feed pipe 8 with each vortex tube inlet 10 is such that incoming returns are fed tangentially relative to the inner surface 11 of the vortex tube. The vortex tube 9 has 21 a transverse top wall 12 forming a central opening 13 for the release of the gas 22 component. The vortex tube also has a transverse bottom wall 14 closing its bottom 23 end. The vortex tube side wall 15 forms peripheral openings 16 at its bottom end for 24 the discharge of liquid and solids. T he tapered feed pipe 8 is designed to supply 21~4801 approximately equal amounts of returns to each vortex tube at about the same fluid 2 velocity.
3 A horizontal vortex breaker plate 14 is suspended from the bottom ends 4 of the vortex tubes 9 in close proximity to the peripheral openings 16. The breaker plate 14 extends laterally beyond the vortex tubes but is inwardly spaced from the 6 vessel side wall 3.
7 The bottoms of the vortex tubes 9 are spaced above the bottom head 5, 8 so as to form a lower section 20 of the chamber 6. The tops of the vortex tubes 9 are 9 spaced below the top head 4 to form an upper section 50 of the chamber 6.
A pair of liquid outlets 21, 22 extend through the vessel side wall 3 at 11 positions above the bottoms of the vortex tubes 9. The outlets 21, 22 are vertically 12 spaced apart whereby the lower outlet 21 is used to discharge water and the upper 13 outlet 22 discharges oil. A pair of openings 23, 24 are positioned above the liquid 14 outlets 21, 22 respectively. Conventional float assemblies 25, 26 are mounted in the openings 23, 24 to actuate conventional dump valves 27, 28 to maintain pre-16 determined liquid levels as well as to control the discharge of water and oil through 17 lines 29, 31 respectively.
18 The bottom head 5 forms a central outlet 32 which is connected to a 19 slurry pump 33 by a solids discharge line 34. The pump 33 is used to withdraw solids form the base of the separator under pressure while the inflow of the returns is21 continued.
22 Installed in the top head 4 is a central baffle deflector 38, against which 23 the gas impinges, to trap residual liquid droplets in the gas. The deflector 38 is 24 inwardly spaced from the vessel side wall 3. The gas discharges through outlet 36 which connects with a gas discharge line 37.
In operation, the incoming returns are tangentially introduced through 2 feed pipe 8 and inlets 10 into the bores 35 of the vortex tubes 9. Each vortex tube 3 receives about the same amount of returns moving at about the same velocity. In each 4 vortex tube, the returns stream components separate under the influence of centrifugal force to form: a central gas vortex, which reverses itself and exits upwardly through 6 the opening 13, across the baffle 38 and exits through outlet 36 and gas discharge line 7 37; an outer layer of solids which rotates downward through the vortex tube bore 35 8 and discharges through the vortex tube bottom peripheral openings 16; and an 9 intermediate layer of liquid located between the gas vortex and the solids layer, which also rotates downward through the vortex tube bore 35 and also discharges through 11 the bottom peripheral openings 16. In the chamber lower section 20, the solid bit 12 cuttings settle and separate from the liquid. The cuttings are concentrated as they 13 funnel through the diminishing cross-sectional area defined by the bottom head 5 and 14 are withdrawn from the chamber 6 by the pump 33 and are discharged through the line 37. The liquid collects as a separate layer in the chamber 6 above the solids layer.
16 Oil and water separate in this layer by gravity separation. The water and oil are 17 individually dumped through lines 29, 31 under the control of float assemblies 25, 26 18 and dump valves 27, 28. The layer or level of liquid in chamber 6 covers the vortex 19 tube peripheral openings 16 to provide an effective seal that prevents gas from escaping or blowing out of the vortex tube bottom openings.
21 The separation process in the separator is characterized by the following 22 advantages:
23 ~ the gas is efficiently separated in the vortex tubes, and is 24 removed as an upwardly moving stream, so that it does not create a turbulence that would disturb liquid and solids;
21 ~4801 ~ the solids and liquids separate efficiently in the chamber outside 2 the vortex tubes, under quiescent conditions;3 ~ there is improved efficiency of the separation process utilizing a 4 mechanical device (vortex cluster); and ~ due to these improved efficiencies, a smaller sized vessel can be 6 used.
Claims (4)
1. A separator for separating the liquid, solids and gas components of pressurized drilling fluid returns from a well undergoing drilling, comprising:
a vertical cylindrical pressure vessel having top and bottom end walls and a side wall, said walls forming an internal chamber;
a cluster of vertical vortex tubes positioned inside the vessel chamber between the vessel top and bottom walls, so that upper and lower chamber sections extend above and below the vortex tubes;
each vortex tube having a side wall forming a bore, said side wall having an inlet at its upper end for tangentially introducing returns into the bore, the vortex tube being open at its upper end and closed by a transverse wall at its lower bottom end, said side wall forming at least one peripheral opening at its lower end for discharging liquid and solids;
means for feeding returns to each vortex tube through its inlet;
the vessel bottom wall being elliptical and having a central outlet;
means for withdrawing solids through the vessel bottom wall outlet;
outlet means for discharging gas from the upper chamber section; and outlet means, located above the bottom ends of the vortex tubes, for discharging liquids through the vessel side wall.
a vertical cylindrical pressure vessel having top and bottom end walls and a side wall, said walls forming an internal chamber;
a cluster of vertical vortex tubes positioned inside the vessel chamber between the vessel top and bottom walls, so that upper and lower chamber sections extend above and below the vortex tubes;
each vortex tube having a side wall forming a bore, said side wall having an inlet at its upper end for tangentially introducing returns into the bore, the vortex tube being open at its upper end and closed by a transverse wall at its lower bottom end, said side wall forming at least one peripheral opening at its lower end for discharging liquid and solids;
means for feeding returns to each vortex tube through its inlet;
the vessel bottom wall being elliptical and having a central outlet;
means for withdrawing solids through the vessel bottom wall outlet;
outlet means for discharging gas from the upper chamber section; and outlet means, located above the bottom ends of the vortex tubes, for discharging liquids through the vessel side wall.
2. The separator as set forth in claim 1 wherein the vessel side wall forms vertically spaced apart water and hydrocarbon liquid outlets positioned above the bottom ends of the vortex tubes.
3. The separator as set forth in claim 2 comprising:
a transverse baffle positioned in the upper chamber section between the gas outlet means and the vortex tubes, for deflecting gas flow therebetween to remove residual liquid in the gas.
a transverse baffle positioned in the upper chamber section between the gas outlet means and the vortex tubes, for deflecting gas flow therebetween to remove residual liquid in the gas.
4. A method for separating the components of pressurized drilling fluid returns from a well undergoing drilling, said fluid comprising bit cuttings, liquid, which may include produced oil, and gas, comprising:
providing a vertical pressure vessel having top, bottom and side walls which form an internal chamber, said vessel containing at least one vertical vortex tube having a top opening, a closed bottom and a peripheral opening at its bottom end, said vessel having a returns feed pipe connected with the upper end of the vortex tube to feed returns tangentially to the inner surface of the vortex tube, the bottom of the vortex tube being spaced above the vessel bottom wall so that the vessel chamber includes a bottom section between the vessel bottom wall and the bottom of the vortex tube, the bottom wall having a central outlet at the base thereof, the vessel side wall having vertically spaced apart oil and water discharge outlets spaced above the bottom of the vortex tube, the vessel having a gas outlet at its upper end;
feeding returns into the upper end of the vortex tube so that they rotate downward through the tube bore and form a central gas vortex, an outer layer of solids and an inner layer of liquid;
discharging the gas out of the upper end of the vortex tube and through the gas outlet;
discharging liquid and solids from the vortex tube through its peripheral opening into the chamber bottom section and temporarily retaining them in the chamber so that they separate by gravity separation under quiescent conditions to form a bottom layer of solids and an upper layer of liquid;
withdrawing solids through the vessel's bottom wall outlet while maintaining the inflow of returns into the vessel; and discharging separate individual streams of oil and water through the liquid discharge outlets at restricted rates so that the bottom outlet of the vortex tube remains submerged in liquid at all times.
providing a vertical pressure vessel having top, bottom and side walls which form an internal chamber, said vessel containing at least one vertical vortex tube having a top opening, a closed bottom and a peripheral opening at its bottom end, said vessel having a returns feed pipe connected with the upper end of the vortex tube to feed returns tangentially to the inner surface of the vortex tube, the bottom of the vortex tube being spaced above the vessel bottom wall so that the vessel chamber includes a bottom section between the vessel bottom wall and the bottom of the vortex tube, the bottom wall having a central outlet at the base thereof, the vessel side wall having vertically spaced apart oil and water discharge outlets spaced above the bottom of the vortex tube, the vessel having a gas outlet at its upper end;
feeding returns into the upper end of the vortex tube so that they rotate downward through the tube bore and form a central gas vortex, an outer layer of solids and an inner layer of liquid;
discharging the gas out of the upper end of the vortex tube and through the gas outlet;
discharging liquid and solids from the vortex tube through its peripheral opening into the chamber bottom section and temporarily retaining them in the chamber so that they separate by gravity separation under quiescent conditions to form a bottom layer of solids and an upper layer of liquid;
withdrawing solids through the vessel's bottom wall outlet while maintaining the inflow of returns into the vessel; and discharging separate individual streams of oil and water through the liquid discharge outlets at restricted rates so that the bottom outlet of the vortex tube remains submerged in liquid at all times.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002194801A CA2194801A1 (en) | 1997-01-10 | 1997-01-10 | Separator and method for separating components of pressurized drilling fluid returns |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002194801A CA2194801A1 (en) | 1997-01-10 | 1997-01-10 | Separator and method for separating components of pressurized drilling fluid returns |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2194801A1 true CA2194801A1 (en) | 1998-07-10 |
Family
ID=4159624
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002194801A Abandoned CA2194801A1 (en) | 1997-01-10 | 1997-01-10 | Separator and method for separating components of pressurized drilling fluid returns |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2194801A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111119764A (en) * | 2018-11-01 | 2020-05-08 | 中国石油化工股份有限公司 | Gas invasion preventing device and drilling string comprising same |
| CN113289382A (en) * | 2021-07-28 | 2021-08-24 | 山东鹤鹏技术有限公司 | Petrochemical fluid distribution device based on simultaneous operation of multiple servo motors |
-
1997
- 1997-01-10 CA CA002194801A patent/CA2194801A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111119764A (en) * | 2018-11-01 | 2020-05-08 | 中国石油化工股份有限公司 | Gas invasion preventing device and drilling string comprising same |
| CN113289382A (en) * | 2021-07-28 | 2021-08-24 | 山东鹤鹏技术有限公司 | Petrochemical fluid distribution device based on simultaneous operation of multiple servo motors |
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |