CA1073824A

CA1073824A - Gas separator

Info

Publication number: CA1073824A
Application number: CA261,282A
Authority: CA
Inventors: Richard F. Salant
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1975-10-08
Filing date: 1976-09-15
Publication date: 1980-03-18
Also published as: AU502021B2; GB1537560A; AU1792276A; AR214725A1; DE2645561A1; NL7610569A

Abstract

ABSTRACT

A gas separator, especially for use with a sub-mersible well pump, having a substantially conical-shaped mesh covered member in the path of flow of gas-laden fluid.
The fluid flows through the mesh gas bubbles are trapped by the mesh and are swept by the flow to a location where they are removed from the separator. Any particulate foreign matter in the gas-laden fluid is trapped by the mesh and is swept along with the gas bubbles to the gas removal location.

Description

074246-BWL 1 0 73~24 This invention relates to gas separators, especially for use with submersible well pumps which are used to pump oil from deep wells. About seventy-five percent of pumps sold annually in the United States for pumping oil rom deep wells are equipped with some form of gas-oil separators.
Many oil wells exist which have gas-oil ratios too high to economically produce oil at this time. In the Middle East, gas-oil ratios are high and, production rates are also high.
To improve the production of gas-free oil, and to permit the economical production of oil from some wells in the United States, especially in these times when there is a serious energy crisis and where it is prudent to be self-supporting in the production of oil, the concept of producing gas-free oil from wells in which the gas-oil ratlo is high becomes extremely important.
' The prior art types of gas-oil separators are generally not entirely successful in providing a substantially gas-free product. Some of the known separators are combined with a pump and use impellers mounted on the drive shaft of the pump to impact a swirling motion to the gas-oil mixture which induces the gas to migrate toward theIshaft, i from which location it is removed. Such a device appears to be useful for eliminating gas locking of the pumps, it is questionable that the device produces a substantially gas-free product.

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107382~
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One of the problems encountered in submersible well pumps is that of geometry; i.e., the size of the device is restricted tothe size parameters of such pumping devices, which may vary in diameter from about 4 inches to about 6 3/4 inches to be used in well casings which may vary from 4 1/2 inches to 8 5/8 inches in diameter. These pump assemblies may have a length, including the motor and usual seal section of approximately ten to thirty feet or more.
The separator, to be functional, must be included within these parameters and within the diameter of the pump assembly.

Other types of- gas separators are known in the art;
usually they are not for use in down hole applications.
They use porous members or filters placed in the flow stream which do not permit gas to pass; the gas is removed via a vent. All or parts of such filters may be wetted by the liquid. In order to prevent gas blockage of some filters, the filter element is constructed with both liquid wetted and liquid repellent parts, The liquid wetted parts will pass the liquid; the liquid-repellent parts will not be wetted by liquid and will remain open for the passage of gas, Prior art patents are U. S. Patents Nos. 3,175,501, 3,2 a 5,816, 3,291,057 and 3,300,950, illustrating various forms of centrifugal gas-oil separators~

Other types of gas separators are to be seen in U. S. Patents Nos. 3,492,793 and 3,631,654,

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According to this invention, an improved gas-liquid separator, particularly adaptable for use with deep well submersible pumps and adaptable for the parameters of such pumps, comprises a multi-pored member positioned in the path of a gas-liquid mixture flowing to the inlet of the pump, which member permits the passage of the liquid while, because of surface tension, does not permit the passage of gas bubbles.
The invention is particularly adapted for use with pumps which handle gas-oil mixtures; reference to gas-oil mixtures and gas-fluid mixtures are intended to be generic to the problem of separating a gas from a liquid (whatever the liquid may be), The multi-pored member is preferably a mesh having a sub-stantially conical shape which spans, preferably at its basel end, the bore of the pump housing and, at its other ~`
end, is positioned in juxtaposîtion to the pump shaft. Gas outlet means are operatively associated with one end of the multi-pored member. In the preferred embodiment, the mesh, which may be of nylon, stainless steel or other suitable material, is supported by a frame member having a plurality of openings therethrough. It has also been found that efficiency of the device is improved when the gas-laden oil flows~into the basel end of the multi-pored member and the `
gas is removed at its opposite ends, which is adjacent to ~ ~ ~the pump inlet and to the shaft.

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When observing a model of such a device, it has been noted that there is a self-sweeping action of the gas `~ bubbles; i.e., they move, together with an amount of bleed ~ ;~
oi~l, upwardly along the mesh from inlet to gas discharge location~ The discharge has a relatively high gas-oil ratio, ~t - _3_ .
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''',: . . ,, ' 10'738Z4 much higher than the entering gas-oil ratio. This action has an interesting effect on particles of foreign particulate material which collects on the mesh. This material also migrates upwardly to be discharged with the gas bubbles; thus providing what may be referred to as self-cleaning screen or mesh. Thus, the mesh does not become clogged with such material which could result in a reduction in efficiency, frequent inspection, replacement or cleaning; therefore maintenance on the device is minimal.
In summary of the above, therefore, the present invention may be broadly defined as providing a gas separator for separating gas and any particulate materlal from a flowable mixture of liquid, gas and any particulate material~ the separator comprising a multi-pored cone-like member adapted to be disposed in the path of all the flow of the flowable mixture into a housing, the multi-pored member permitting the passage therethrough of substantially gas-free liquid while trapping gas bubbles and any particulate material in the flowable mixture; passage means being connected with the multi-pored cone-like member for the removal from the member of any trapped ga~ bubbles and particulate material, the flow of the liquid sweeping trapped gas bubbles and any particulate material along the mem~er to the passage means for removal therefrom.
In the accompanying drawings:
FIGURE 1 is a schematic illustration of a gas-oil separator constructed according to this invention in the structural arrangement for use with submersi~le well pumps;
FIGURE 2 is a longitudinal sectional view showing constructional details of the gas-oil separator of this invention in the same or similar arrangement illustrated in FIGURE l; and FIGURE 3 illustrates performance curves of two cone 3~ arrangements.
Referring now to FIGURE 1 of the drawings, there is ~chema~i~ally illustrated, an arrangement which includes a gas-oil separator G positioned bet~een a pump P and a prime mover or motor M, the latter having a driven shaft S

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which passes centrally through the separator G. A seal section U is located between the separator G and the motor M. These parts are in an elongated cylindrical housing which is adapted to be lowered into a well The separator G comprises a multi-pored conical member 10, and in the preferred embodiment, the multi-pored member comprises a mesh, The basel end of the cone is located adjacent the gas-oil inlet 12. Oil passes through the mesh to the pump P. Bubbles of gas do not pass through the mesh and are swept upwardly toward the apex of of the cone by the flow of the liquid near the apex. There is a means permitting the passage of a gas-oil mixture having a gas-to-oil ratio much higher than the gas-to-oil ratio entering the cone, through radial gas outlets 14 which, when more than one is provided, are arranged in a spoke-like pattern. The gas-oil mixture is discharged to the annular regionbetween the separator housing and the well casing.

Referring now to FIGURE 2, the gas separator G
comprises a housing 20 adapted to be connected between a pump housing 22 and a motor and seal housing 24, so as to ., ~ :
form an integral part of a submersible pump assembly for lowerLng in a well casing 26 (only a portion of which is shown)~. The composite housing 20, 22, 24 is of such diameter to be spaced from the well casing 26.

The pump P may be constructed according to U. S.
Patent 3,242,360 and is illustrated here only schematically.
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' ' ~0738Z4 The seal section u may be constructed according to u. s.
Patent No. 3,153,160, and, like the pump, is illustrated here only schematically In any case, the motor has a shaft S, extending through the seal section U, through the gas separator G and into the pump P and on which the pump impellers are mounted. Because of the length of the shaft S, s~
it may be made in several parts suitablc joined together. In the gas separator, the shaft S is supported by anti-friction journals 28, 29 at the opposite ends of the housing 20.

The housing 20 is provided, at one end, with the inlet passage or passages 12 for the flow of fluid ultimately to the separatox G and an outlet or outlets 30 for the flow of oil, substantially gas-free, to the pump P. In addition, there are one or more outlets 32 from the housing 20 which open into the casing 26 for the discharge of gas-rich oil :
back into the casing from the separator G.

Within the separator housing 20, is a conical-shaped member 34 having a plurality of elongated openings 36 therethrough, which as shown in FIGURE 2, has its large or ~:
basel end 38 adjacent to the inlet passages 12. This end is constructed with a cylindrical flange 40 having an outside diameter substantially equal to the inside diameter of the housing 20 and is formed with an annular groove 42 to receive an O-ring seal 44 in order to sealingly engage the interior of the housing 20, insuring the passage of all fluid into the interior of the cone member 34.

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, The opposite end of the cone member 34 is also formed with a cylindrical flange 48 having an outside diameter also substantially the same as the inside diameter of the housing 20. This flange 48 is provided with an annular groove 50 to receive an O-ring seal 52 to sealingly engage the interior of ths housing 20 The flange 48 is provided with a plurality of openings 54 as shown in broken lines. The end 46 of the cone member 34 has an inside diameter substantially the same as the diameter of the shaft S, permitting the shaft to rotate while the cone remains stationary. Between the ends of the cone member, there are spoke-like conduits 56 which communicate the inside of the cone 34 with the outlets 32 in the housing 20.
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A mesh 58, for example of nylon, stainless steel or other suitable material, lines the interior of the cone i ~ 34~ ~he mesh is such to permit the passage of oil; bubbles . .
of gas and also particulate foreign material if present, are trapped and do not pass the mesh. The flow of the oil-gas mixture upwardly continually sweeps the gas bubbles and forelgn particles toward the outlet conduits 56, making the mesh self-cleaning.

To provide a continuous flow of gas-laden fluid to tbe~separator, an impeller I may be used. This impeller may be constructed as is the impeller in the gas separator ; of~the Carle patent No, 3,300,950, which is primaxily to eliminate gas lock of the pump. Other types o impellers can~be used Lf desired.

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~073824 The cone member may be constructed of stainless steel or a relatively cheap plastic, or other material, so long as the material will not distort or disintegrate in the environment The mesh material 58, as stated before, can be of stainless steel, nylon or other suitable material.
The mesh material may be of different mesh size at different locations relative to the cone without departing from the scope of this invention, Also, while the cone has been described as having its basel end near the inlet for the gas-oil mixture, it may be inverted. In this arrangement, the gas outlet is in juxtaposition to thei~hY~ (upper) end of the cone~ The length of the cone may also vary.

However, in experimental tests, it has been found that improved results occurred when the cone was used as described and illustrated in the preferred embodiment.

FIGURE 3, is a curve for experimental work showing -the output of substantially gas-free oil in gallons per minute plotted against the i~put of a No. 1 fuel oil in S
gallons per minute to which ahc been added 16~8 standard cubic feet per hour of air. In this experimental work, one cone was 9 inches in length; another was 5 13/16 inches in length the mesh was a 310 x 310 nylon mesh in each case, and the inner diameter of the housing was approximately 2.3 inches. The curve for the 9 inch cone is identified as A; that for the S 13/16 inch cone is identified as B. The . ,' , . ' arrangement of the cones was substantially as described inthe description of the preferred embodiment and as illustrated in the drawing. The open areas of the cones A and B were, respectively, approxLmately 76% and 84% of the total surface area, the open area of course being covered by the mesh.
The experiments were performed at ambient temperature, approximately 70F. As can be deducted from the curves there, the gas separation varies with input feed rate; it reaches an upper level and then drops of as the input feed rate increases.
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Further experiments were performed in which ~--~' approximately 1/2 to 1% of sand, based on the volume of input oil, was bled into the system; other variables were substantially the same as described above. It was observed ~, ; . :
~ that;the product was substantially gas-free. Sand particies : :
~ ~ were observed being swept to the gas outlet.
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Addltional experiments have been conducted using high~vlscosity oils - higher than the No. 1 grade fuel oil.
Small gas bubbles were observed in the oil output but with .; ~
conventLonal laboratory equipment, the quantity of the gas bubbles~was too small to be measured The experiments above were conducted with a 310 nylon mesh;~practical mesh sizes of about 50 to about 400 ~ can~be used.l It haS been observed that using larger mesh :,jA" ~ sizes~(smaller openings) the performance at low levels is substantially the same as described; as the flow rate in-creases, the efficiency increases.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A gas separator for separating gas and any particulate material from a flowable mixture of liquid, gas and any particulate material, said separator comprising a multi-pored cone-like member adapted to be disposed in the path of all the flow of the flowable mixture into a housing, said multi-pored member permitting the passage therethrough of substantially gas-free liquid while trapping gas bubbles and any particulate material in the flowable mixture:
passage means being connected with the multi-pored cone-like member for the removal from the member of any trapped gas bubbles and particulate material, the flow of the liquid sweeping trapped gas bubbles and any particulate material along the said member to the passage means for removal therefrom.

2. A gas separator as claimed in claim 1 wherein the cone-like member has a plurality of openings therethrough which are covered with mesh material through which the flowable mixture is constrained to flow.

3. A gas separator as claimed in claim 2 wherein the cone-like member is disposed with its largest end adjacent an inlet thereto and its smallest end adjacent to an outlet therefrom.

4. A gas separator as claimed in claims 1-3 wherein the cone-like member comprises stainless steel mesh.

5. A gas separator as claimed in claims 1-3 wherein the cone-like member comprises a plastic mesh or nylon.

6. A separator assembly for separating gas and any particulate material from a flowable mixture of liquid, gas and any particulate material which assembly is adapted to be associated with a motor and a pump driven by said motor for pumping the liquid therefrom comprising:
a housing having a pair of spaced ends;
inlet means at one end of said housing communicating with a source of said flowable mixture;
an outlet from the other end of said housing in communication with an inlet of said pump means for the passage of liquid from the separator assembly to said pump means;
outlet means for the flow of separated gas and any particulate material from said housing together with a small amount of bleed liquid;
a stationary generally conical-shaped multi-pored member in said housing having its basel end spanning the housing and maintained in sealed relation with respect to the interior walls thereof and its other end generally centrally located in said housing;
one end of said multi-pored member being an entry end for said flowable mixture and the other end being an exit end;
said outlet means being connected to said exit end of said multi-pored member;
said pump means providing a continuous flow of said flowable mixture into said housing through said inlet means and to said entry end of said multi-pored member and the continuous flow of separated liquid and separated gas and any particulate material and bleed liquid to the outlet and outlet means;
said multi-pored member being so disposed in said housing to intersect the flow of all mixture which flows into and through said inlet means and to said entry end and having pores of such dimensions to permit the passage therethrough of said liquid while trapping gas in the form of bubbles and any particulate material, said trapped bubbles of gas and any particulate material being moved and swept along said multi-pored member in the general direction of continuous mixture flow and to said exit end and through said outlet means.

7. Separator assembly for separating gas from a flow-able mixture of oil and gas and which assembly is adapted to be positioned in a well and between a submersible motor and a pump driven by said motor with a motor shaft passing centrally through said separator assembly, said pump pumping the oil therefrom, comprising:
a housing having a pair of spaced ends;
inlet means at one end of said housing communicating with a source of said flowable mixture;
an outlet from the other end of said housing in communication with the inlet of said pump for the passage of oil from the separator assembly to said pump;
outlet means for the flow of separated gas from said housing together with a small quantity of bleed oil;
a stationary generally conical-shaped mesh member in said housing having its basel end spanning the housing and main-tained in sealed relation with respect to the interior walls there-of and its other end generally centrally located in said housing;
said basel end being an entry end and said other end being an exit end;
said outlet means being connected to said exit end of said mesh member;
impeller means positioned below said housing connected to said motor shaft and driven by said motor, said impeller means and said pump providing a continuous flow of said flowable mixture into said housing through said inlet means and into the basel end of said mesh member and the continuous flow of separated oil and separated gas and bleed oil to said outlet and said outlet means;
said mesh member being so disposed in said housing to intersect the flow of all mixture which flows into and through said inlet means to the basel end thereof and having a mesh size to permit the passage therethrough of said oil while trapping gas in the form of bubbles of gas, said trapped gas being moved and swept along the mesh member inwardly to said exit end and through said outlet means by the continuous flow of mixture to and through said assembly.

8. A separator assembly for separating gas from a flowable mixture of a liquid, gas and any particulate material comprising:
a housing having a pair of spaced ends;
an inlet to one end of said housing adapted to communicate with a source of said flowable mixture;
an outlet at the other end of said housing and an outlet means for the flow of separated liquid and gas with any particulate material from said housing;
a conical mesh member in said housing, one end of which is maintained in sealed relation to the interior walls of said housing and located between said inlet and said outlet, said member having an entrance end into which all said flowable mixture flows, said mesh member permitting the flow therethrough of separated liquid to said outlet;
said outlet means being connected to said mesh member adjacent an end removed from said entrance end;
said gas and any particulate material being trapped by said mesh member and being moved along its surface to and through said outlet means; and means for providing a continuous flow of said flowable mixture to said inlet into said housing and to the entrance end of said mesh member and the flow of the separated liquid and separated gas with any particulate material to the outlet and outlet means, respectively.

9. A separator for use in a well and associated with a pump for pumping a liquid therefrom comprising:
a generally cylindrical housing having a pair of spaced ends;
an inlet to one end of said housing for receiving a flow into said housing of a flowable mixture comprising liquid and non-liquid material;
an outlet from the other end of said housing for the flow of liquid;
outlet means from said housing for the flow comprising non-liquid material;
a multi-pored cone-like member in said housing having one end maintained in sealed relation to the interior walls there of and receiving all the flow of said mixture from said inlet into said housing;
said multi-pored member having a porous surface permitting the passage therethrough to said outlet of liquid while trapping non-liquid material on the surfaces thereof;
said outlet means being connected to said cone-like member at a location removed from the said one end thereof;
the continual flow of said mixture to said multi-pored member and the flow of liquid through the porous surface of said multi-pored member sweeping trapped non-liquid material along said surfaces to said outlet means and from said housing.

10. A separator assembly for separating non-liquid materials from a flowing mixture of such materials and a liquid, said assembly being adapted to be connected to a pump and a motor for driving said pump, said separator comprising:
a housing having an entrance end and an exit end;
an impeller-diffuser assembly in said housing adjacent said entrance end;
. an inlet to said impeller and an outlet from said impeller-diffuser assembly;
a conical mesh member in said housing between said impeller-diffuser assembly and said exit end;
said conical mesh member having one end spanning said housing such that the flow of mixture is intercepted thereby;
said mesh member having an inlet communicating with the outlet of said impeller-diffuser assembly;
said mesh member having an outlet communicating with a surface thereof;

said housing having an outlet adjacent said exit end;
and said mesh member being so constructed to permit the passage therethrough of liquid to said housing outlet while retaining on said surface non-liquid materials, the flow of mixture and liquid sweeping said non-liquid materials to said outlet of said mesh member.