|Publication number||USRE39292 E1|
|Application number||US 10/879,890|
|Publication date||Sep 19, 2006|
|Filing date||Jun 29, 2004|
|Priority date||Feb 24, 1998|
|Also published as||CA2320903A1, CA2320903C, US6138757, WO1999042701A1|
|Publication number||10879890, 879890, US RE39292 E1, US RE39292E1, US-E1-RE39292, USRE39292 E1, USRE39292E1|
|Inventors||Gordon D. Latos, John E. Ravensbergen|
|Original Assignee||Bj Services Company|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (25), Referenced by (14), Classifications (9), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This invention relates to fluid downhole separators and fluid separating, and more particularly to downhole fluid separators using centrifugal separating techniques and wherein a plurality of fluids pumped downhole are separated and where the separation is particularly useful in coiled tubing operations.
There are occasions in the oil and gas industry when a gas may be pumped downhole together with a liquid phase such as a treatment fluid or a drilling fluid. In particular it may be useful to pump nitrogen gas downhole during drilling or during well workover operations. There could be a variety of purposes for pumping downhole a gas with a liquid phase. Such purposes might include helping to lift liquids back to the surface and/or lowering the pressure exerted by the combination of fluids against fragile welllbores. “Underbalanced” drilling, for instance, typically utilizes a gas added to a drilling fluid to “underbalance” the pressure between the drilling fluid and portions of the formation that are open downhole.
One illustration of a well workover application where it might be useful to pump gas downhole is in rotary jet cleaning. In rotary jet cleaning a liquid is pumped downhole and out of a rotary jet cleaning tool. Gas could be advantageously added to the liquid in so far as the gas could help lift and circulate the cleaning liquid back up hole, possibly enhancing the liquid's capacity to carry debris. Drilling with a downhole motor and rotary jet drilling might have similar applications in which it could be advantageous to add gas to a working liquid, at least for lifting purposes. However, running mixed gas/liquid phase through a downhole hydraulically powered motor or other apparatus, such as a downhole drilling motor or a rotary jet cleaning tool, is not favored. The gas/liquid phase neither optimizes downhole motor performance nor optimizes maintenance of the motor parts. Sending a mixed gas/liquid phase through a rotary jet cleaner, in addition, may result in the loss of optimum cleaning power.
One aspect of the instant invention, therefore, is a methodology and apparatus affording the ability to remove a gas phase at or in a bottomhole assembly (BHA) when the presence of the gas downhole could be helpful but when it would also be useful to prevent the gas from invading and damaging elastomers in a drilling motor and/or to optimize the cleaning performance of a rotary jet cleaner by excluding a gas phase.
Existing commercially available downhole liquid/gas flow separators seem to be designed for separating production fluids. These are fluids flowing up either under natural pressure or being pumped. These separators appear optimized for narrow ranges of gas volume fraction and/or for high values of entry or initial gas volume fraction. They appear typically optimized for entry gas volume fractions of between 90% and 100% and for exit gas volume fractions of between 15% and 50%. See U.S. Pat. No. 5,482,117, column 1, line 58. These entry ranges are too high and too narrow to be useful for generally separating fluid mixtures, in particular gas/liquid mixed phase fluids, that might be pumped downhole in either a drilling application or in a jetting application or in other workover applications. The exit volume fractions are also too high.
The problems involved in cost effectively, efficiently and sufficiently separating pumped fluids flowing downhole are different from the problems involved in sufficiently separating well fluids produced into a well to be flowed or pumped up.
A further aspect of the present invention includes the design of an efficient and effective downhole fluid phase separator, which includes gas/liquid separating, that can effectively and efficiently operate without excessive loss of pressure to the fluid pumped downhole and can operate over a range of supplied gas volume fractions that might run from 10% through 90%. Further, the separator must not be too long. Important aspects of the invention include the length of the separator, ideally below three (3) feet, and the pressure drop caused by the tool, preferably below 10% of the supplied fluid pressure. The outside diameter of the tool will be limited by the diameter of the wellbores through which the bottomhole assembly is designed to run. Simplicity of operation and the absence of moving parts are further advantageous features found in embodiments of the instant design which enhance the value of the tool.
Disclosed herein is a preferred embodiment for a fluid (particularly including liquid/gas) phase separator for use on fluid mixtures pumped downhole, and its methods of use. One prime application lies with coiled-tubing-based downhole operations. The device separates fluids by density, including nitrified treatment fluids and nitrified drilling fluids. The fluids are separated into at least two constituent phases or portions. The device can be structured and designed to optimize the separation of one stream, such as a liquid stream, so that the stream is relatively free of a second fluid, such as a gas. “Relatively” in the instant environment means at least 75% free. Preferred embodiments have achieved significantly greater percentages of separation.
For purposes herein fluids are distinguished or characterized as separate fluids by their density, or at least by their capacity to be separated by density. Use of the term fluid mixture implies a mixture of fluids with different densities or at least a mixture of fluids that can be separated into at least two streams by density. The disclosed tool and method separate a fluid mixture into at least two fluid streams by density and subsequently permit directing each stream to a different path in accordance with useful applications.
In the present invention separating fluids by density is preferably achieved by inducing centrifugal acceleration, or a swirling flow path, to a moving fluid stream. Preferably a significant annular flow is first or also induced within the limits of space available. Preferably also a gradually expanding flow path in terms of cross-sectional area of flow is defined in a chamber that receives centrifugally accelerated fluids.
It should be understood that the distinct stages of the disclosed preferred embodiment herein could be overlapped in alternate designs. Distinct steps disclosed by the preferred embodiment could be made simultaneous or partially simultaneous. The instant design facilitated testing of functionality. With the present design the length of the tool has been shown to be able to be satisfactorily minimized, as has the loss of head pressure for the pumped fluids due to the separation process. High efficiencies in the separation of gas from liquid have been shown to be achievable.
In regard to gas/liquid separation, which is a prime application, shop tests have indicated that a separation efficiency can be achieved such that less than three percent (3%) of the original gas is left in a liquid fluid stream. This was achieved with a tool having less than three feet of length (More than 3% of the original liquid may or may not be left in the gas, as this may not be a critical parameter.) It will be understood that multiple stages could be utilized to improve further gas separation efficiency. Alternately, gas separation efficiency could be improved by accepting more liquid in the gas discharge stream.
The combination of features designed into preferred embodiments of the tool, and designed into preferred embodiments of the methodology disclosed, advantageously provides the ability to function effectively, efficiently and economically under significant size and performance limitations, as required for downhole operations.
The invention teaches a downhole method and apparatus for separating fluids flowing through a passageway in a well. The method includes centrifugally accelerating flow of fluid downhole through at least a portion of a downhole passageway and separating centrifugally accelerated fluid by density into at least two fluid streams. In one aspect the novel method includes pumping a fluid mixture downhole and centrifugally accelerating and separating at least a part of the fluid pumped downward. Fluid pumped “downward” is intended to cover fluid flowing in the wellbore in the direction from the well head or surface and toward the well toe or bottom. It is conceivable that fluid in this “downward” flow path (which is to be distinguished from flow of fluid in the well “upward” or toward the surface) could literally be flowing, gravitationally speaking, “up” for a period of time (or at least not gravitationally “down”, as in a horizontal wellbore.) In a second aspect the novel method includes receiving centrifugally accelerated fluid in a chamber defining a flow path having a cross-sectional area of flow that gradually increases. (As illustrated, this can be accomplished without increasing the outside diameter of the flow passageway.) In a third aspect the novel method includes centrifugally accelerating flow of fluid through at least a portion of a downhole passageway wherein the centrifugal acceleration occurs at an increasing rate. A fourth aspect of the invention involves establishing in at least a portion of a downhole well passageway annular fluid flow with the annular flow path having a cross-sectional area of flow with an average radius greater than 75% of the passageway radius. (Passageway radius refers to one-half of the ID of the housing defining the passageway). The average radius of fluid flowing through a passageway with an open (unobstructed) cross-sectional area of flow, for example (as the term average is used herein) would be 50% of the passageway radius. When the term “average” radius is used, the average of all of the distances out from center of the passageway at which fluid flows is meant. No account is intended to be taken, in speaking of an “average” radius, of the fact that a greater volume of fluid flows at a greater radius. A fifth aspect of the invention includes gradually establishing annular fluid flow, preferably prior to or during centrifugal acceleration, in at least a portion of a downhole passageway.
Various combinations of the above embodiments can be practiced. In one preferred embodiment at least two separated fluid streams include a predominately liquid stream and a predominately gas stream. Embodiments of the tool have shown an ability to separate out from a liquid/gas mixed phase a liquid stream that contains less than 5% gas by volume in the liquid stream.
Preferred embodiments have also shown an ability in tests to separate out at least one fluid stream with a head pressure loss through the tool of less than 10% of the tool to wellbore pressure differential.
In the disclosed embodiment the centrifugal accelerating occurs subsequent to the establishment of annular flow. This is not totally necessary. The embodiment disclosed sequentially performed the steps of establishing annular flow, centrifugally accelerating and then receiving into a chamber of gradually expanding cross-sectional area of flow. The embodiment performed well. However, one of skill in the art would realize that the stages could be overlapped or the steps could be performed to a certain extent simultaneously.
The invention includes apparatus for separating fluids flowing in a downhole passageway in a well. One aspect of the apparatus includes a pump attached at the surface to tubing attached to a downhole well assembly where at least a portion of the downhole assembly defines a fluid passageway. At least one vane is attached within a passageway defined by at least a portion of the downhole assembly, the vane passageway being in fluid communication with the pump. Means are provided, in fluid communication with the vane passageway, for separating centrifugally accelerated fluid by density into at least two fluid streams.
In regard to means for separating centrifugally accelerated fluid, the prior art teaches a great variety of alternate designs for separating centrifugally accelerated fluids into at least two streams. The selection of the most appropriate means is a matter of design choice. The choice would likely relate to the prime uses for the device. The instant structure disclosed for performing the separation should be recognized as just one of many different designs known. Selection of individual means is best left to estimates of the prime use for the apparatus and the prime use for the separated streams.
A further aspect of the apparatus of the invention includes at least one vane attached within a passageway defined by at least a portion of a downhole well assembly, together with a chamber in fluid communication with the vane passageway where the chamber defines a flow path having a cross-sectional area of flow that gradually increases. A third aspect of the apparatus of the present invention includes at least one vane attached within a passageway defined by at least a portion of downhole assembly where the vane has a pitch angle graduating from low to high in the direction of flow. A fourth aspect of the apparatus includes a portion of a downhole assembly defining an annular passageway. Preferably the annular passageway defines a flow path having a cross-sectional area of flow with an average radius greater than 75% of the annular passageway radius. A fifth aspect of the invention includes a portion of a downhole assembly defining an annular passageway wherein the annular passageway has gradually increasing annularity in a direction of fluid flow.
Various combinations of the above apparatus embodiments or aspects may be constructed. In one preferred embodiment the vane passageway is located in the downhole assembly downstream of the entry to the annular passageway. Further, in preferred embodiments the apparatus is less than three feet long; the annular passageway of gradually increasing annularity is achieved by locating a diverging tapered barrier, or cone, within a passageway; and the chamber having an increasingly larger cross-sectional area of flow is achieved by locating a tapered barrier, or cone, in that passageway, the taper converging in the direction of flow. In general, as the cross-sectional area of a tapered barrier or cone decreases, the cross-sectional area of flow in a passageway surrounding the barrier increases, and vice versa.
A further aspect of the present invention includes a method for operating a downhole assembly with tubing, preferably coiled tubing, that comprises pumping a fluid mixture down tubing to a downhole assembly, separating the fluid mixture downhole by density into at least two fluid streams and using at least one fluid stream with a downhole assembly tool. In preferred embodiments the downhole assembly tool might be a downhole assembly motor or a downhole assembly jetting tool. The method might also include venting at least one fluid stream to the wellbore. In some embodiments the separating of fluids will separate the fluid mixture into a predominately liquid stream and a predominately gas stream. The invention also includes apparatus for use downhole in a well comprising tubing, preferably coiled tubing, attached to a downhole assembly, a pump attached at the surface to the tubing and a fluid separator associated with the downhole assembly, the fluid separator being operable to separate by density the fluid mixture pumped down the tubing into at least two fluid streams. Preferably the apparatus includes a tool associated with a downhole assembly in fluid communication with at least one separated fluid stream. The tool may comprise a downhole motor or a downhole jetting tool. Preferably the fluid separator is a centrifugal separator.
The invention will be better understood and objects other than set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:
A preferred embodiment of the instant apparatus, which was designed particularly for the separation of a liquid/gas mixture downhole and for test purposes, is illustrated in
Transition cone 5, downstream of turning vanes 8 (in the preferred embodiment there are five turning vanes) gradually increases the cross-sectional area of flow of the centrifugally accelerated fluid.
A first fluid or lighter fluid extraction port 6 is centered downstream in housing 1 for collecting the lighter fluid stream which would migrate by density toward the center of the passageway. Bypass sub 7 routes the heavier fluid stream which would migrate toward the outer periphery of bore 2 onward to the rest of the downhole assembly. Bypass sub 7 also permits venting the first fluid to the wellbore through vent ports 13. Alternate embodiments might retain the lighter fluid and route it along a path parallel to the heavier fluid phase.
Extraction port 6 and bypass sub 7 form one means for separating centrifugally accelerated fluids, such as gas and liquid, by density into at least two streams. Those familiar with centrifugal separators will be familiar with other design choices for separating into two streams of centrifugally accelerated fluid. The intended application should dictate the design choice of the separation means.
The “annularity” of the downhole passageway increases, and increases smoothly and gradually, in the disclosed embodiment as fluid flows over diverter 3 from left to right. A passageway of increasing annularity is created, being a passageway whose cross-sectional area of flow has an increasing average radius. The notion of “average” radius is discussed above.
The flow path through turning vanes 8 disclosed in
Concentric extraction port 6, as illustrated in
A computer model was developed and used to design the 1¾ inch prototype tool illustrated in
Even though separation efficiency is quite high for the preferred embodiment, it is clear that multiple stage designs could be utilized, for instance in the event that gas leaving solution below a first stage should become unacceptable.
A key aspect of the present invention is illustrated in FIG. 4.
While there are shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the scope of the following claims. ACCORDINGLY,
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US336317 *||Oct 18, 1884||Feb 16, 1886||Process or method of operating gas-wells|
|US1279758 *||Sep 24, 1917||Sep 24, 1918||James K Putnam||Separator for wells.|
|US2329745||Oct 15, 1940||Sep 21, 1943||Reed Roller Bit Co||Means for protecting bearings of roller bits|
|US2652130 *||Jun 26, 1950||Sep 15, 1953||California Research Corp||Gas-oil separator|
|US3094175||Sep 15, 1959||Jun 18, 1963||Well Completions Inc||Well drilling apparatus and method|
|US3291057 *||Nov 12, 1964||Dec 13, 1966||Borg Warner||Gas separator for submersible pump|
|US3625288 *||Apr 14, 1970||Dec 7, 1971||Roeder George K||Method and apparatus for venting gas through a downhole pump assembly|
|US4015662||Oct 23, 1975||Apr 5, 1977||Brown Oil Tools, Inc.||Well tool which changes reciprocating movement to rotary motion|
|US4074763 *||Dec 17, 1976||Feb 21, 1978||Chevron Research Company||Bottom-hole gas-liquid separator|
|US4241788 *||Jan 31, 1979||Dec 30, 1980||Armco Inc.||Multiple cup downwell gas separator|
|US4448607||Sep 20, 1982||May 15, 1984||Sun Chemical Corporation||Conditioning crude phthalocyanine pigments|
|US4481020 *||Jun 10, 1982||Nov 6, 1984||Trw Inc.||Liquid-gas separator apparatus|
|US4531584 *||Feb 6, 1984||Jul 30, 1985||Blue Water, Ltd.||Downhole oil/gas separator and method of separating oil and gas downhole|
|US4981175 *||Jan 9, 1990||Jan 1, 1991||Conoco Inc||Recirculating gas separator for electric submersible pumps|
|US5173022 *||Oct 1, 1990||Dec 22, 1992||Societe Nationale Elf Aquitaine (Production)||Process for pumping a gas/liquid mixture in an oil extraction well and device for implementing the process|
|US5240083||Apr 21, 1992||Aug 31, 1993||Ingersoll-Rand Company||Device for removing drillhole debris|
|US5291956||Apr 15, 1992||Mar 8, 1994||Union Oil Company Of California||Coiled tubing drilling apparatus and method|
|US5314018 *||Jul 30, 1992||May 24, 1994||Cobb Delwin E||Apparatus and method for separating solid particles from liquids|
|US5355967 *||Oct 30, 1992||Oct 18, 1994||Union Oil Company Of California||Underbalance jet pump drilling method|
|US5394951||Dec 13, 1993||Mar 7, 1995||Camco International Inc.||Bottom hole drilling assembly|
|US5431228 *||Nov 28, 1994||Jul 11, 1995||Atlantic Richfield Company||Downhole gas-liquid separator for wells|
|US5482117 *||Dec 13, 1994||Jan 9, 1996||Atlantic Richfield Company||Gas-liquid separator for well pumps|
|US5662167 *||Mar 18, 1996||Sep 2, 1997||Atlantic Richfield Company||Oil production and desanding method and apparatus|
|US5693225 *||Oct 2, 1996||Dec 2, 1997||Camco International Inc.||Downhole fluid separation system|
|US6039116 *||May 5, 1998||Mar 21, 2000||Atlantic Richfield Company||Oil and gas production with periodic gas injection|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7905946||Aug 12, 2008||Mar 15, 2011||The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration||Systems and methods for separating a multiphase fluid|
|US7938203 *||Oct 25, 2010||May 10, 2011||Hall David R||Downhole centrifugal drilling fluid separator|
|US7980332 *||Oct 25, 2010||Jul 19, 2011||Hall David R||Downhole centrifugal drilling fluid separator|
|US7984772 *||Oct 25, 2010||Jul 26, 2011||Hall David R||Downhole centrifugal drilling fluid separator|
|US8584744 *||Sep 13, 2010||Nov 19, 2013||Baker Hughes Incorporated||Debris chamber with helical flow path for enhanced subterranean debris removal|
|US8844619||Sep 13, 2013||Sep 30, 2014||Baker Hughes Incorporated||Debris chamber with helical flow path for enhanced subterranean debris removal|
|US8881803||May 21, 2014||Nov 11, 2014||Cavin B. Frost||Desander system|
|US9080443 *||Oct 25, 2012||Jul 14, 2015||Premiere, Inc.||Method and apparatus for downhole fluid conditioning|
|US9157307 *||Aug 27, 2014||Oct 13, 2015||Thru Tubing Solutions, Inc.||Downhole gas separator|
|US9353590 *||Sep 16, 2014||May 31, 2016||Baker Hughes Incorporated||Debris chamber with helical flow path for enhanced subterranean debris removal|
|US20120061073 *||Sep 13, 2010||Mar 15, 2012||Baker Hughes Incorporated||Debris Chamber with Helical Flow Path for Enhanced Subterranean Debris Removal|
|US20130105152 *||Oct 25, 2012||May 2, 2013||Premiere, Inc.||Method and Apparatus for Downhole Fluid Conditioning|
|US20150000896 *||Sep 16, 2014||Jan 1, 2015||Baker Hughes Incorporated||Debris Chamber with Helical Flow Path for Enhanced Subterranean Debris Removal|
|US20150068741 *||Aug 27, 2014||Mar 12, 2015||Thru Tubing Solutions, Inc.||Downhole gas separator|
|U.S. Classification||166/265, 166/105.5|
|International Classification||E21B21/14, E21B43/38, E21B21/00|
|Cooperative Classification||E21B21/14, E21B21/002|
|European Classification||E21B21/00F, E21B21/14|
|Apr 18, 2008||FPAY||Fee payment|
Year of fee payment: 8
|Apr 11, 2012||FPAY||Fee payment|
Year of fee payment: 12