Gas Separator For A Submersible Oil Pump

Abstract

A gas separator interposed between a submersible pump and electric motor includes a plurality of flow diversion means including a coaxial impeller for impelling well fluid through a spiral gas separator chamber wherein entrained gas is centrifugally separated from the well fluid. The disentrained gas is subsequently returned to the well fluid basin while the well fluid passes from the gas separator chamber into the inlet of a submersible pump.

Description

BACKGROUND OF THE INVENTION

This invention relates to gas separators and more particularly to a gas separator for use with a submersible pump for oil and gas wells.

In oil and gas well operation, it is common practice to utilize a submersible pump having therebelow and coupled thereto an electric driving motor.

In oil and/or gas wells in which the submersible pump is to be installed, free and/or entrained gas is produced along with the well fluid being pumped. If this gas enters the submersible pump the volumetric and mechanical efficiency of the pump is reduced and in some instances produces a gas lock of the pump.

It is therefore an object of this invention to present a gas separator for use with a submersible pump which substantially prohibits entrance of the gas into the inlet of the submersible pump.

SUMMARY OF THE INVENTION

Generally the gas separator of this invention is interposed between a pump and the electric driving motor therefor and comprises a housing containing within the interior thereof an impeller which assists the propulsion of well fluid normally on its flow to the pump intake through a separation chamber where gas is centrifugally disentrained from the well fluid. The disentrained gas passes into and through a gas-collecting receptacle and subsequently is returned back into the well fluid basin while the well fluid progresses from the gas separation chamber into the inlet of the pump. The inlet to the impeller includes a plurality of vertically nested inlet cylinders or cups through which the flow of fluids is controlled.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawings is a partial cross-sectional view of the lower segment of the gas separator of this invention showing the same longitudinally disposed within a well casing.

FIG. 2 of the drawings is a partial cross-sectional view of an intermediate portion of the gas separator.

FIG. 3 is a partial cross-sectional view of the upper portion of the gas separator of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The gas separator of this invention generally denoted as the numeral 10 is interposed between a pump designated as block 12 on the drawings and pump-driving motor denoted as block 14. The pump is driven by motor 14 through a coaxial shaft 16 extending longitudinally through gas separator 10. Suitable splines 18 are provided on shaft 16 for appropriate connections with the respective shafts of the pump and motor.

The interconnected pump, gas separator 10, and pump driving motor 14, form an integral unit for insertion within the casing 20 of an oil or gas well. When received within the well casing 20, the outer wall of separator 10 is spaced relative to the inner wall of the well casing so as to permit flow of well fluid 22 therebetween. Well fluids may include oil, gas and water or combinations thereof. In operation gas separator 10 is at least partially submerged in the well fluid basin and preferably totally submerged therein.

The separator 10 is composed of a plurality of inlet cup members coaxially assembled or nested. A base member 24 is provided at the lower end thereof with a flange 26 for connection with a mating flange on the housing of pump-driving motor 14 in a conventional manner and includes a hollow interior within which shaft 16 is splined or otherwise coupled to the shaft of motor 14.

The upper end of base member 24 is provided with an upstanding circular flange having, in this instance, outer peripheral threads for engaging the lower end of an elongated cylindrical housing 28 which terminates its upper end by connection with a tubular adapter 30 having a plurality of longitudinal fluid apertures 32. The adapter 30 is outwardly notched to form a circular receiving surface 34 which receives and carries the lower edge of a cylindrical cup support 36. A plurality of transverse oval ports 38 are adjacent the upper end of support 36.

The upper peripheral edge of cup support 36 is flat to receive longitudinally nested cylindrical cup members 40A, 40B, 40C, 40D and 40E. Each cylindrical cup member includes an upper portion and at the lower end thereof a downwardly projecting inset portion 42 with an interlocking surface 44 to receive the next adjacent cup member therebetween.

Lip portion 42 of lowest cup member 40A projects downwardly into the interior of cup support 36. The interlocking surface 44 of the highest cup member 40E receives the lower end of a head member 46 which in turn is appropriately secured to the housing of pump 12. Each of the cup members 42A-42E contains therein a plurality of rectangular transverse inlet ports 48 providing access means for well fluid 22 to enter the interior of gas separator 10. Progressing upwardly from the lowest to the highest cup member the area of ports on each succeeding cup member increases to that the volume of well fluid 22 capable of entering the interior of the gas separator through each of the ports also increases from the lowest to the highest cup member.

Turning now to the internal components of gas separator 10, coaxially received over the shaft 16 is a longitudinal sleeve 50, which may be comprised of a plurality of separate nested sleeves.

Secured to base member 24 by bolts and extending upwardly therefrom is a coaxial impeller support 52 which rotatably carries an impeller 54 coaxially affixed to shaft 18 for common rotation therewith. Bearings 56 support the rotation of the impeller. Impeller 54 has therein a plurality of longitudinal openings 57 defining an impeller inlet and outlet.

Coaxially received over shaft 16 directly above impeller 54 is a gas separation chamber 58 composed of an elongated core 60 and possessing an internal gas annulus 62 which communicates with the well basin through upper port 64, and with the outlet of impeller 54 through port 66.

Progressing horizontally outwardly and upwardly from the bottom of the top of the outer wall of core 60 is an upwardly inclined spiraled flange 68 the outer edge of which is bounded by a coaxial encompassing member 70 sleeved thereover and extending downwardly to rest on impeller support 52. The coaxial superpositioning of encompassing member 70 over core 60 and flange 68 creates an annular impeller outlet chamber 72 for accepting fluid expelled by impeller 54 and a continuous enclosed upwardly spiraled passageway 74 through gas separation chamber 58 communicating at the lower end thereof with impeller outlet chamber 72. Intermediate the convolutions of flange 78 transverse ports 76 enable passageway 74 to communicate with gas receptacle 68 at a plurality of points.

Gas separation chamber 58 terminates with an upwardly progressing circular flange 78 having the upper outer peripheral edge thereof notched to engage the inner lower edge of tubular adapter 30.

Threadably received in the inner threads of adapter 30 is the lower end of a tubular member 80 projecting upwardly through cup support 36 and cup members 40A-40E to threadably engage at the upper end thereof the internal threads of head member 46. Tubular member 80 divides the upper portion of the gas separator into an elongated annular well fluid outlet passageway 82 communicating with the inlet of the pump and an elongated annular well fluid inlet passageway 84 which communicates through apertures 32 in adapter 30 with the annular spacing between encompassing member 70 and cup support 36 to provide a well fluid flow route to the inlet of impeller 54.

As can be best seen by FIGS. 2 and 3 of the drawings ports 48 and the lip portions 42 associated therewith form tributaries feeding well fluid 22 into inlet passage 84. Thus well fluid entering through inlet ports 48 in the cup members is channeled downwardly into inlet passageway 84 and subsequently into the inlet of impeller 54.

OPERATION

In operation, a stream of well fluid 22 along with any free and entrained gas molecules enters the separator through inlet ports 48 in the longitudinal cup members 40A-40E (depending on the level) and also through the ports 38 in cup supports 36. The fluid is then channeled downwardly by lip portions 42 into well fluid inlet passageway 84 and continues downwardly through the spacing between the encompassing member 70 and the wall of cup support 36 to the inlet of the impeller 54. During the downward flow of well fluid 22, a portion of the entrained gas molecules becomes disentrained for which reason the receiving of the greatest volume of well fluid in ports 48 in the upper cup members is desirable.

Impeller 54, rotating at same revolutions per minute as the shaft 16, creates a suction force of sufficient magnitude to reverse the flow of well fluid 22 and to draw the same upwardly into the inlet thereof. The well fluid exiting from the outlet of impeller 54 into outlet chamber 72 has imparted thereto a centrifugal force which frees an additional portion of the gas molecules entrained in the well fluid and also drives well fluid 22 upwardly into spiraled passageway 74. The freed gas molecules due to the high pressure thereof pass through port 66 into gas receptacle 62 and from thence through port 64 back into the well basin.

During the passage of well fluid through passageway 74 the centrifugal force disentrains from the well fluid substantially all of the remaining gas molecules which due to the high pressure thereof pass through apertures 76 into gas receptacle 62 and subsequently back into the well fluid basin.

Substantially gas-free well fluid 22 exits from spiraled passageway 74 into outlet passageway 82 where the suction of pump 12 draws the well fluid into the pump inlet from whence the fluid is pumped into fluid-gathering systems.

During the description of preferred embodiments specific language has been used for the sake of clarity, however, it is to be understood that the words used are not words of limitation and include all equivalents which operate in a similar manner to accomplish a similar purpose.

Claims

What is claimed is:

1. A gas separator for a submersible well pump for pumping well fluid from a well basin comprising:

a housing having at least one inlet adapted to admit well fluid within the interior thereof and at least one outlet in communication with the inlet of said submersible well pump;

a rotatable impeller within said housing and within the flow path of said well fluid and adapted to assist said submersible pump in transferring well fluid from said inlet to said outlet, said impeller including means for imparting centrifugal force to said well fluid during transfer thereof whereby gases entrained in said well fluid are disentrained therefrom;

a cylindrical gas separator chamber disposed within said housing between said impeller and said outlet and adapted to receive well fluid from said impeller and conduct same to said inlet of said pump; said gas separation chamber including an internal gas-collecting receptacle in communication with the well fluid basin and the output of said impeller for receiving gas centrifugally separated from said well fluid; said gas separation chamber further including outwardly of said gas-collecting receptacle a spiraled passageway through which said well fluid upwardly passes from said impeller to said pump unit; said passageway being in communication with said gas-collecting receptacle whereby gas disentrained from said well fluid during passage therethrough enters said receptacle and subsequently back into said well basin.

2. A gas separator as in claim 1 wherein said housing is comprised of:

a plurality of cylindrical cups each including a downwardly extending inset portion, said cups being longitudinally nested to form said cylindrical longitudinal housing such that said inset portions on each cup extend downwardly into the next lower cup; each cup including at least one transverse aperture for admitting well fluid within the interior of said housing whereby said well fluid flows downwardly into the inlet of said impeller.

3. A gas separator of claim 2 wherein the transverse apertures of each cup increase in area progressively upward.