US3915225A

US3915225A - Method and apparatus for producing hydrocarbons from wells which make water

Info

Publication number: US3915225A
Application number: US170814A
Authority: US
Inventors: George A Swink
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-08-11
Filing date: 1971-08-11
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28

Abstract

A chamber having openings in the lower end thereof to allow entry of a hydrocarbon-water mixture is provided with upper and lower electronic sensing devices for detecting a hydrocarbonwater interface, both sensing devices being above the openings in the lower end of the chamber. As a hydrocarbon-water mixture enters the chamber, the hydrocarbon will rise and form a layer in the top of the chamber and gradually force the hydrocarbon-water interface downwardly. When the water level drops below the lower sensing device, a pump will be actuated and withdraw the hydrocarbon from the upper end of the chamber until the water level moves up to the higher sensing device, at which time pumping will cease and the chamber will be allowed to fill with hydrocarbon again.

Description

uruwu 01,211.88 1 318K! Swink METHOD AND APPARATUS FOR PRODUCING HYDROCARBONS FROM Primary Examiner-Stephen J. Novosad WELLS WIIICII MAKE WATER [76] Inventor:

Assistant Examiner-Jack E. Ebel Attorney, Agent, or Firm-Stewart N. Rice George A. Swink, 121 E. Scotland,

Irving, Tex. 75062 Aug. 11, 1971 [22] Filed:

[21] Appl. No.1 170,814 A chamber having openings in the lower end thereof to allow entry of a hydrocarbon-water mixture is provided with upper and lower electronic sensing devices [52] US. 166/53; 166/65 R; 210/104;

417136 for detecting a hydrocarbon-water interface, bc-th E2"; 43/00 sensing devices being above the openings in the lower 166/53, 54, 65 R,

[51] Int.

end of the chamber. As a hydrocarbon-water mixture enters the chamber, the hydrocarbon will rise and [58] Field of Search 66, 265; 210/83, 86, 104; 417/113, 118, 138, 36

form a layer in the top of the chamber and gradually force the hydrocarbon-water interface downwardly.

References Cited UNITED STATES PATENTS When the water level drops below the lower sensing device, a pump will be actuated and withdraw the hydrocarbon from the upper end of the chamber until 219/109 210/104 the water level moves up to the higher sensing device, 23/33 at which time pumping will cease and the chamber 12/1966 Meyers et al. 166/54 will be allowed to n with hydrocarbon again FOREIGN PATENTS OR APPLICATIONS Crawford 6/1956 Williams et al. 10/1956 Beckett..........

1.120.417 12/1958 166/53 8 Claims 2 Draw Figures METHOD AND APPARATUS FOR PRODUCING HYDROCARBONS FROM WELLS WHICH MAKE WATER BACKGROUND OF THE INVENTION The present invention relates to a method for producing only hydrocarbons from oil and gas wells which normally produce or make a mixture of hydrocarbons and water, and to an apparatus for carrying out such.

In producing hydrocarbons (which may include oil and/or' gas) from a well, water frequently enters the wells such that the withdrawal of the hydrocarbon is accompanied by considerable quantity of brine or salt water. The removal of such water is undesirable for many reasons. For example, in oil wells the hydrostatic pressure upon the oil in the formation is reduced by the removal of the water. Another objection to removal of water along with the hydrocarbons is that extensive onsurface separators and tanks must be installed and maintained in order to separate the hydrocarbons from the water. In fact in many wells the ratio of water to hydrocarbon is so great that the size of separators and -equipment needed to facilitate separation makes it uneconomical to install them and thus the well must be shut in.

In oil wells, another disadvantage of producing a mixture of oil and water is that an emusion of the oil and water frequently occurs when the mixture passes through the choke at the surface of the earth, such emulsions being quite difficult to break in many instances. Another important factor, in fact perhaps the most important factor. in the operation of wells wherein water is withdrawn is the disposal of the water. As mentioned above, such water is generally salty and thus disposal of such on the surface may cause pollution of the surrounding environment resulting in the destruction of both plant and animal life on land as well as in surrounding streams and bodies of water into which the salt water flows. It is thus an object of the present invention to provide an apparatus and a method for producing only hydrocarbons from well which produces both hydrocarbons and water, so that the hydrostatic pressure of the well will not be unnecessarily reduced and so that on-surface separators will not be needed. Further the production of only hydrocarbons from such a well will reduce or eliminate the problem of oil-water emulsion formation and will serve to help maintain and protect the surrounding environment. Additional objects will become apparent from the following description of the invention and the drawings included herewith.

SUMMARY OF THE INVENTION The present invention in one of its aspects is an apparatus for use in the extraction of hydrocarbons from wells making both hydrocarbons and water, such apparatus being adapted to be attached to the lower end of the production tubing and within the casing, said apparatus comprising (a) a chamber having one or more openings in a lower portion thereof to permit fluids to flow into said chamber and means in the upper end thereof to place the interior of said chamber in open communication with said production tubing whereby fluids may be withdrawn from said chamber into said production tubing, (b) a first sensing device extending into said chamber capable of detecting a hydrocarbonwater interface at a first predetermined level in the upper portion of said chamber which is below said means in the upper end thereof where fluids may be withdrawn, (0) a second sensing device extending into said chamber capable of detecting a hydrocarbonwater interface at a second predetermined level in said chamber. said second predetermined level being below said first predetermined level but above the said openings in the lower portion of said chamber. In another aspect the present invention is a method for producing and withdrawing only hydrocarbons from awell which makes both hydrocarbons and water from an oil producing formation and a water producing formation, which method comprises cyclically (1) allowing a mixture of hydrocarbons and water to flow through openings into the lower portion of a chamber placed in said well while at the same time preventing the flow of fluids from the upper portion of said chamber such that oil accumulates by reason of its specific gravity in the upper portion of said chamber, (2) removing the thus accumulated oil in the upper portion of said chamber therefrom when the hydrocarbon-water interface reaches a predetermined lower level in the chamber which is above said openings in the lower portion thereof and above said water producing formation,

such removal of hydrocarbon being continued until the hydrocarbon-water interface reaches a predetermined upper level in said chamber, the point of removal of the said hydrocarbon from said chamber being above said predetermined upper level.

DETAILED DESCRIPTION OF THE INVENTION FIG. I represents a vertical cross-section of a typical oil well arranged to carry out the invention.

FIG. 2 represents a vertical crosssection of a preferred embodiment of an apparatus of the present invention. The same numbers have been used in the figures to denote corresponding elements.

Referring to FIG. I. a well is shown as having a well hole 10 having a casing II extending downwardly into an oil producing zone 12 and a water zone 13 located below oil zone 12. Casing II has been perforated as indicated by perforations 14, and as indicated, these perforations I4 are not only within the oil zone but also within the portion of casing 11 extending into the water ,zone. Such perforations, or fractures, sometimes extend into both the oil producing formation and the water producing formation adjacent a ,well as shown because of an improper fracture or perforation job. The result ofsuch is that the well will make both oil and water. There are of course many other reasons that a well may make both oil and water including those wells wherein the well hole does not even extend into an underlying water producing formation, and the present invention can be applied to any such wells. It has been found, however, that the invention works best in wells wherein the interior of the casing is in communication with a water zone since water may escape more freely into the water formation. Thus the type of oil well illustrated in FIG. I is merely by way of example and is not to be taken as limiting the kind of well in which the apparatus of the present invention may operate.

Extending downwardly through casing 11 is a string of production tubing 15 having a pump 16 therein. The pump I6 is any type well known to the art. preferably one which is actuated by a reciprocating sucker rod string 17 which is raised up and down by pumping unit 18. The pump may, however, be a centrifugal type placed below the ground. A production flowline I9 is connected to the upper end of tubing and in open communication therewith, the flowline also containing valve therein. Valve 20 is responsive to controller 21 as is pumping unit 18 as indicated by the dashed lines.

Attached to the lower end of tubing 15 and below pump 16 is the apparatus 22 of the present invention. The apparatus is composed of a chamber 23 having perforations 24 in the lower portion thereof and having an opening 25 in the upper end thereof such that the chamber is in open communication at the upper end thereof with the tubing 15 via pump 16. lf desired, an orifice to control the flow to a desired quantity may be placed in opening 25. The apparatus is attached to tubing 15 by means of a threaded portion 26. Extending downwardly into chamber 23 is a rod-like first sensing device 27 and a rod-like second sensing device 28, the

,lower ends of which are capable of detecting an oilwater interface. The lower end of the shorter sensing device 27 is at a predetermined first level and the sensitive lower end of the lower sensing device 28 is at a second predetermined level which is lower than the first predetermined level but above the water zone or formation 13. As also may be seen, the first predetermined level corresponding to the lower sensitive end of sensing device 27 is below opening 25 through which fluids may be withdrawn from chamber 23 into the tubing.

Sensing devices, such as electronic probes, for the detection of an oil-water or gas-water interface are well known. The main requirement of those utilized in the present invention is that they be capable of withstanding the pressures and temperatures encountered. Although it is preferred because of ease of construction and space requirements, it is not necessary that the sensing devices be suspended from the top of the chamber 23. instead the sensing device could be located on the interior side wall of chamber 23 or extending therefrom at the desired predetermined level. Both

sensing device

27 and 28 are capable of sending signals to controller 21 when the oil-water interface is detected as indicated by the dashed lines leading from the upper ends thereof to controller 21. Each dashed line shown in the figures could be one or more wires necessary to accomplish the desired function. It is preferable that any wires leading from apparatus 22 to the surface be tied together in a bundle and enclosed within a protective metal and/or synthetic covering. Controller 21 may of course be placed below the ground and even incorporated into the structure of apparatus 22.

In addition to the foregoing elements, there is a packer 29 which is above the casing perforations l4 and chamber perforations 24. Packer 29 serves to seal the annular space between apparatus 22 and casing 11. Packer 29 may be of any of the conventional types known in the industry, such as a J-type packer, which is capable of providing the desired sealing action at the pressures to be encountered. There is also a valve 30 located between apparatus 22 and pump 16 which will be used in start-up operations as hereafter explained. Valve 30 may be actuated by any desirable means as by electrical means or by mechanical means. For example. valve 30 may be a ball valve which is positively seated by a spring, and opened by a plunger which unseats the ball such as by a twist of the tubing or the lowering of sucker rod 17.

At the beginning of operations of the equipment illustrated in HO. 1, the equipment will be situated as illustrated. Tubing 15 as well as the annular space between casing 11 and tubing 15 will generally be filled with an oil-water mixture and it is desirable that this be replaced with oil before starting operations. With valve 30 closed, valve 20 in flowline l9 will then be opened and pumping unit 18 started so as to remove the oilwater mixture from the tubing so that it may be replaced with only oil from a surface supply. As pointed out it is also preferable to remove the oil-water mixture between the casing and tubing before beginning operations to prevent corrosion of tubing. wires and the like and also to aid in detecting a leaking packer 29. Pumping of the casing water may be accomplished by such as by providing closable perforations in the tubing at a point between valve 30 and pump 16. These perforations would be closed by a shut-off device, such as those actuated by a twist of the tubing or lowering of the sucker rod after the oil-water mixture had been removed from the annular space and replaced with oil. After the foregoing is accomplished, operations may begin for withdrawing oil from the oil zone 12. First, the leads from sensing

device

27 and 28 are connected to controller 21 and the controller programed such that when water is in contact with the sensitive lower end of sensing device 27 then valve 20 will be closed and pumping unit 18 will be inoperative; and such that valve 20 will open and pumping unit 18 will start when an oil-water interface drops below the end of sensing device 28.

if it has not already done so, a mixture of oil and water will then pass or continue to pass into casing ll through perforations 14. The oil-water mixture entering the casing will be prevented from migrating upwardly by packer 29 and will thus seep into chamber 23 through perforations 24. Due to the difference in specific gravities of oil and water, the oil entering chamber 23 will migrate upwardly and fill the upper part of chamber 23 and the tubing up to the point of valve 30. As more oil seeps into the chamber, the oil-water interface will gradually drop lower and lower within chamber 23 forcing water in the lower part of the chamber outwardly through perforations 24. When the oil-water interface eventually drops below the end of the longer sensing device 28, valve 30 will then be opened by the appropriate means; and valve 20 will be opened and pumping unit 18 started by controller 21 in response to the signal from sensing device 28. Valve 20 will remain open and pumping will continue such that oil is withdrawn through opening 25 until the oil-water interface rises to the lower sensitive end of sensing device 27. At this point in time, controller 21 will cause valve 20 to close and pumping unit 18 to stop until enough oil seeps into chamber 23 to once again force the oil-water interface to fall below the end of sensing device 28. Of course at this time pumping will once again resume with valve 20 open. With respect to the operation of pumping unit 18, it has been found that a slow, short stroke is best since such lessens the tendency of the water to follow the hydrocarbon through opening 25.

The foregoing explanation with respect to FIG. 1 is by way of illustration only and is not to be taken in a limiting sense. For example, as was explained above. valve 30 is only for the purpose of emptying the casing and tubing of water and, once opened, remains open throughout future operations. Obviously other means than that described above could be used to remove the oil and water in the tubing and/or casing at the beginning of operations and thus valve 30 could be eliminated entirely if desired. Also the apparatus 22 does not have to be placed near the bottom of the well hole but can instead be up the hole above the oil-producing zone. Orie of the main requirements is that the sensitive lower end of electrode 28 not be within the zone or formation which produces the water entering the casing; otherwise the oil-water interface in chamber 23 will not generally drop below the end of sensing device 28 so as to start pumping unit 18. Also, FIG. 1 represents an oil well yet the present invention will operate satisfactorily in wells which produce only gas and water or produce oil, gas and water. Of course, if only gas and water are present then valve and pumping unit 18 would be responsive to a gas-water interface, and gas would be the fluid withdrawn through opening 25. In wells making gas, oil and water, there would be formed in chamber 23 an upper gas layer, a middle oil layer and a lower water layer, with valve 20 and pumping unit 18 being responsive to the oil-water interface. in the latter type -of wells, the gas would first be withdrawn through opening followed by the oil.

F IG. 2 illustrates a preferred method for constructing the apparatus 22 of the present invention. As can be seen, this particular apparatus 22 contains a sealed upper compartment 31 in which valve 32 is located in line 33 which places chamber 23 in communication with the production tubing. Valve 32 is for example, a solenoid valve and is responsive to

sensing devices

27 and 28 via controller 21. The controller would be programmed to open valve 32 when the oil-water interface reaches the sensitive lower end of sensing device 28 and to close valve 32 when the oil-water interface dropped below sensing device 27. Upper compartment 31 is sealed and preferably filled with transformer fluid in order to help protect solenoid valve 32. The seal 34 through which the wires or leads from sensing

devices

27 and 28 and valve 32 exit chamber 31 could be in the form of a male or female plug adapted to receive a cable from controller 21. As may be seen chamber 23 is reduced in diameter at point 35, the purpose of such being that a packer may be placed at the point 35 of reduction and provide a more positive sealing action than on those apparatuses wherein there is no reduction in size.

Because of the small diameters of well holes and casings, the reduction of size of chamber 23 may necessitate placement of sensing device 28 in the center of chamber 23 as shown so that such sensing device may extend downwardly to the desired level. Also FIG. 2 illustrates the preferred practice of placing a protective sheath 36 around and coaxial with sensing device 28. in order to allow the oil-water'interface to move up and down in the annular space between sheath 36 and senthat illustrated and could for example, merely be a perforated, hollow sphere surrounding the lower end of sensing device 28.

Many other modifications could be made of the apparatus 22 as illustrated in FIGS. 1 and 2 and still be within the scope of the invention. Thus additional compartments could be placed on the apparatus to house various components. By way of example, controller 21 could be placed in a sealed compartment above compartment 31 of FIG. 2. Also instead of, or in addition to, perforations 24, the bottom of chamber 23 could be completely open.

Uses for the apparatus of the present invention other than the separation of hydrocarbons and water will also be apparent. For example, in the event of a fire at the well head, valve 32 of FIG. 2 could be closed so as to prevent the flammable oil or gas from reaching the well head and thus terminate the fire. This closing of valve 32 would usually occur automatically in such cases because solenoid valves are normally closed and therefore a loss of power (such as that caused by a fire) to the valve would result in its automatic closing.

By the term "hydrocarbons" as used herein is meant all of the hydrocarbons that are produced from wells including those which are normally a gas, such as natural gas, methane, and the like, and those which are normally liquid, such as oil, or as it is sometimes called, petroleum.

What is claimed is:

1. An apparatus for use in the extraction of hydrocarbons from wells making both hydrocarbons and water, such apparatus being adapted to be attached to the lower end of the production tubing and within the casing, said apparatus comprising (a) a chamber having one or more openings in a lower portion thereof to per mit fluids to flow into said chamber and means in the upper end thereof to place the interior of said chamber in open communication with said production ttibing whereby fluids may be withdrawn from said chamber into said production tubing in response to the hereafter defined first and second sensing devices, (b) a first sensing device extending into said chamber capable of detecting a hydrocarbon-water interface at a first predetermined level in the upper portion of said chamber which is below said means in the upper end thereof ,where fluids may be withdrawn, (c) a second sensing device extending into said chamber capable of detecting a hydrocarbon-water interface at a second predetermined level in said chamber, said second predetermined level being below said first predetermined level but above the said openings in the lower portion of said chamber.

2. The apparatus of claim 1 wherein said chamber contains a plurality of openings in a lower portion thereof.

3. The apparatus of claim I wherein both said first sensing device and said second sensing device are rodlike elements the lower ends of which are capable of sensing an oil-water interface, both said first device and said second device being suspended from the upper end of said chamber, said second device being longer than said first device.

4. The apparatus of claim 3 wherein said second se nsing device is surrounded by a sheath of electrically nonconductive material said sheath being of a size such that there is a space between said sheath and said second sensing device, said sheath having at least one opening therein at a point above said second predeter- 7 8 mined level. and at least one opening therein at a point 7. The apparatus of claim 6 wherein said means in the below Said Second Pledelermlned levelupper end of said chamber whereby fluids maybe with- The aPpmaum Ofclalm. 1 wherein Said means in the drawn includes valve means to control the flow offiuids upper end of Said chamber whereby fluids may bs from said chamber, said valve means being located in drawn includes valve means responsive to said first and 5 second sensing devices, said valve means being for controlling the flow of fluids from said chamber.

6. The apparatus of claim 1 wherein said first sensing device and said second sensing device are electronic and send electrical signals in response to the detection 10 cfimduclive materialof the hydrocarbon-water interface.

a sealed compartment above said chamber and being responsive to said first and second sensing devices.

8. The apparatus of claim 7 wherein said second sensing device is protected by a sheath of electrically non-

Claims

1. AN APPARATUS FOR USE IN THE EXTRACTION OF HYDROCARBONS FROM WELLS MAKING BOTH HYDROCARBONS AND WATER, SUCH APPARATUS BEING ADAPTED TO BE ATTACHED TO THE LOWER END OF THE PRODUCTION TUBING AND WITHIN THE CASING, SAID APPARATUS COMPRISING (A) A CHAMBER HAVING ONE OR MORE OPENINGS IN A LOWER PORTION THEREOF THE PERMIT FLUIDS TO FLOW INTO SAID CHAMBER AND MEANS IN THE UPPER END THEREOF TO PLACE THE INTERIOR OF SAID CHAMBER IN OPEN COMMUNICATION WITH SAID PRODUCTION TUBING WHEREBY FLUIDS MAY BE WITHDWAWN FROM SAID CHAMBER INTO SAID PRODUCTION TUBING IN RESPONSE TO THE HEREAFTER DEFINED FIRST AND SECOND SENSING DEVICES, (B) A FIRST SENSING DEVICE EXTENDING INTO SAID CHAMBER CAPABLE OF DETECTING A HYDROCARBONWATER INTERFACE AT A FIRST PREDETERMINED LEVEL IN THE UPPER PORTION OF SAID CHAMBER WHICH IS BELOW SAID MEANS IN THE UPPER END THEREOF WHERE FLUIDS MAY BE WITHDRAWN, (C) A SECOND SENSING DEVICE EXTENDING INTO SAID CHAMBER CAPABLE OF DETECTING A HYDROCARBON-WATER INTERFACE AT A SECOND PREDETERMINED LEVEL IN SAID CHAMBER, SAID SECOND PREDETERMINED LEVEL BEING BELOW SAID FIRST PREDETERMINED LEVEL BUT ABOVE THE SAID OPENINGS IN THE LOWER PORTION OF SAID CHAMBER.

3. The apparatus of claim 1 wherein both said first sensing device and said second sensing device are rod-like elements the lower ends of which are capable of sensing an oil-water interface, both said first device and said second device being suspended from the upper end of said chamber, said second device being longer than said first device.

4. The apparatus of claim 3 wherein said second sensing device is surrounded by a sheath of electrically nonconductive material said sheath being of a size such that there is a space between said sheath and said second sensing device, said sheath having at least one opening therein at a point above said second predetermined level, and at least one opening therein at a point below said second predetermined level.

5. The apparatus of claim 1 wherein said means in the upper end of said chamber whereby fluids may be withdrawn includes valve means responsive to said first and second sensing devices, said valve means being for controlling the flow of fluids from said chamber.

6. The apparatus of claim 1 wherein said first sensing device and said second sensing device are electronic and send electrical signals in response to the detection of the hydrocarbon-water interface.

7. The apparatus of claim 6 wherein said means in the upper end of said chamber whereby fluids may be withdrawn includes valve means to control the flow of fluids from said chamber, said valve means being located in a sealed compartment above said chamber and being responsive to said first and second sensing devices.

8. The apparatus of claim 7 wherein said second sensing device is protected by a sheath of electrically non-conductive material.