US3161140A - Fluid actuated downwell pump - Google Patents

Description

P. S- BLOUDOFF FLUID ACTUATED DOWNWELL PUMP Dec. 15, 1964 Filed March 20, 1962 FILTERS INVENTOR. PETER S. BLOUDOFF BY 2 2 ATTORNEYS 3,lhl,ld Patented Dec. 15, 1964 3,161,140 FLUID ACTUATED DOWNWELL PUMP Peter S. Bloudoii, Whittier, Califl, assignor to Armco' Steel Corporation, Middletown, Ohio, a corporation of Uhio Filed Mar. 20, 1962, Ser. No. 181,0% 2 Ciaims. (Cl. 1ti346) This invention relates to fluid actuated downwell pumps for oil wells and is particularly directed to a structure that is especially adapted for use in wells producing oil that carries a high solids content.

It has heretofore been recognized that fluid actuated downwell pumps are operable only with difiiculty in wells where the production fluid contains a high percentage of paraffin. These pumps are operated by clean oil which is usually conveyed from the surface through a small diameter string of tubing known as a macaroni string, and-the production fluid and spent power oil are returned to the surface through the annulus between the well tubing and the macaroni string. In some instances, of course, separate return strings are provided for spent power oil and for production fluid. As the production fluid approaches the surface, parafiin which will remain in solution at the temperature of the system adjacent the pump condenses out of solution and adheres to the inner walls of the tubing and the outside walls of the macaroni string. When the accumulation is such that the passage is severely restricted, the pump must be shut down, the macaroni string pulled and cleaned and a swab sent down the tubing to remove the parafiin from its walls. This is a time consuming and costly operation.

In the installation according to the present invention, power oil is pumped down the annulus between the macaroni string the tubing and the production is forced up through the macaroni string. The invention is especially concerned with means to remove paraifin and other contaminating materials without pulling the macaroni string. Means are provided to clean the entire system if neces sary, or to clean the macaroni alone. This latter means includes a valve provided in the fitting which attaches the pump to the macaroni string, which valve is normally closed, but can be opened when the circulation in the well is reversed. By this simple expedient, the areas which collect paraifin during production can be cleaned without pulling the pump from the well merely by inserting a soluble plug in the macaroni string, forcing it down towards the pump and removing the accumulated paraflin out through the annulus, the circulation of fluid being thus reversed during the cleaning operation. To complete the cleaning operation, if desired, the pump can be raised from its seat in the well fittings, and clean fluid circulated in the system. During this circulation, clean power oil passes through the pump in a direction normally taken by pumped production fluid. The clean power oil is prevented from going out into the formation by the conventional standing valve assembly which is in stalled below the pump.

The installation according to the present invention does not involve the well casing in any way, nor does it require the separate side strings frequently associated with so called free pump installations. The present invention is applicable to pumps falling under the category of fixed pump" installations, and is especially advantageous for so-ealled slim-hole completions in which the diameter of thestring in which the pump isseated may be less than three inches. i

A well installation according to the present invention is shown diagrammatically in the accompanying drawings, in which:

FIG. 1 is a central, longitudinal, sectional view, with parts broken away and with other parts shown in full lines of an apparatus according to the invention in its normal operating position;

FIG. 2 is a fragmentary view of the parts shown in FIG. 1 indicating the circulation of fluid and the position oi the parts during cleaning; and

FIG. 3 is another fragmentary and diagrammatic view showing the position of the parts during an additional cleaning step.

Referring to the drawings, and particularly to FIG. 1., the present invention is shown in conjunction with a well having an outer slim casing string it) carrying certain conventional bottom hole elements such as a screen 12 adjacent the producing formation. A pump anchor packer 14 is disposed within the string 10 and a standing valve 16 is attached to the anchor in a known manner. The valve it? opens during the normal suction stroke of the pump and closes during the discharge stroke.

A fiuid actuated downwell pump unit 20 may also be a conventional unit and may be constructed and operated as described in Brennan and Bloudoff Patent No. 2,921,531, issued January 19, 1960. The pump unit is seated in the packer 14- during normal operation as shown in FIG. 1. The pump will he treated herein as a unit which is attached to the lower end of a macaroni string 22. In most installations the macaroni is used to carry power oil to the pump, but in the present instance the normal circulation is such that power oil flows down the annulus 24 between the macaroni string 22 and the casing it), and returns to the surface in the macaroni string 22. A supply connection .26 crosses over from the an nulus 24 to the inlet of the pump engine to cause reciprocation of the engine and pump pistons as shown in the Brennan and Bloudoil patent above mentioned.

A lower pump inlet valve 28 is shown in dotted lines in FIG. 1, and the discharge of production fluid from the pump is through a peripheral series of discharge ports 3h into the annulus 32 between the exterior of the pump engine cylinders and the pump jacket which is designated 34. The spent power oil is discharged through a separate series of spaced ports 36 into the same annulus, and the mingled power oil and production fluid goes to the surface through the macaroni 22.

The surface equipment used with the present invention and by which power oil is put under pressure and circulated is shown very diagrammatically in FIG. 1. A conventional triplex pump 38 takes power oil from a sump 40, increases its pressure to several thousand pounds and discharges it into a power oil supply conduit 42, through a four-way valve 44 to a line 45 leading to the annulus 24 for circulation to the pump. The returned fluid, comprising comingled spent power oil and production oil, flows from the macaroni string 22 into a line 46, through 'a shut-off valve 47 and into a filter 43. A portion of this returned oil is led to a storage line or tank (not shown) and another portion is filtered and cleaned to be used as power oil. The cleaned oil is taken to sump 40 through a shut-off valve 49. In accordance with the requirements of the present invention which will become apparent, provision is made for reversing the circulation and discharging power oil from the pump 38 into the macaroni string 22 and for taking fluid from the annulus 24 back to the filters 48. For this purpose the fourway valve 44 is provided with ports which will connect the pump discharge line 42 to the line 46 ahead of the shut-off valve 47, while a second reversible valve 59, normally closed during operation, is opened to connect a by-pass line 52 between the'macaroni string and the filters 48.

In many wells the production fluid carries a high percentage of paratlin and similar solids which remain in solution at the temperatures existing at the producting horizon but which condense out and accumulate on the Walls of the conduit in which it flows to the surface. The accumulation becomes troublesome after a period of time and so restricts the flow that it must be removed. In many instances removal can be accomplished only by pulling the pump and scraping the accumulated solids away. This is particularly true if the return conduit is annular. The present invention is particularly directed to a simple and inexpensive expedient by which solids removal may be accomplished quickly and without pulling the pump and disassembling the macaroni.

The present invention provides a valve 55 preferably carried at the connection between the pump unit and the macaroni string 22 and opening in the direction of the power oil annulus 24 which may be operated from the surface. In the preferred form, the valve 55 is a simple check valve which opens whenever the pressure in the macaroni string 22 predominates over the pressure in the annulus 24. During normal operation the check valve 55 remains seated because the pressure of power oil in the annulus 24 is greater than the discharge pressure of the pump unit into the macaroni 22. However, when the circulation is reversed so that power oil is put into the macaroni string and fluid exhausted from the annulus 24, valve 55 will open.

At the well head, provision is made for a removable cap 57 or any other suitable expedient by which the interior of the macaroni string becomes accessible. A plug of parafiin or other soluble material can be placed through the opening of the cap 57, into the macaroni string. When the circulation is reversed so that power oil flows from the four-way valve 44 and into the macaroni string 22, the soluble plug can be circulated down the macaroni string, scraping paraffin from the interior of the walls of the macaroni string as it goes and forcing the accumulated solids into the annulus 24 through the now opened check valve 55. If the soluble plug is of paraffin or similar material, it will dissolve at the high temperatures encountered towards the lower end of the macaroni string where there is no accumulation of solids so that the plug itself never reaches the check valve 55. By this simple expedient, accumulated solids may be scraped from the interior of the macaroni string 22 without removing the pump from the well or without in any way disassembling the macaroni and associated elements. This circulation is indicated in FIG. 2, the soluble plug being designated 59 in this figure. During this cleaning operation, the four-way valve 44 is turned to connect power oil supply conduit 42 with the line 46 and the reversing valve 50 is turned at the same time to connect line 45 from the annulus 24 into the by-pass 52 leading to the filters 48, the fluid from the annulus 24 being thus at low exhaust pressure at this point. Valve 47 will be shut 011 so that power oil pressure does not appear at the filters.

By reversing the circulation as above described, accumulated solids are removed from the interior of the macaroni string. If it is desired to further clean the well and particularly to remove accumulated solids from the pump itself, the present invention provides means to raise the pump unit from its seat as indicated in FIG. 3. Since the pump is normally seated on the anchor 14, raising the pump from the anchor will permit power oil from the annulus 24 to enter through the pump inlet valve 28 and circulate through the pump to carry ahead of it any sand, paraflin or accumulated materials. These materials are forced out through the pump discharge ports 30 into the annulus 32 between the pump cylinder and pump jacket 34 to return to the surface in the macaroni string 22. This circulation in the normal direction does not operate the pump engine, however, because the pressure at the discharge ports of the pump is essentially the same as the pressure at the engine inlet port or crossover 26. The pump with which the present invention is particularly applicable operates on a pressure differential principle and if there is insufficient pressure differential between the upper and lower faces of the pump piston the pump engine will not reciprocate. Thus the pressure of power oil at the inlet valve 28 simply raises the valve from its seat, causing the clean oil to pass through the pump in the direction normally taken by production fluid. The power oil cleans out the pump itself, and passes all of the accumulated contaminating material back to the surface. The valve 55 remains closed during this cleaning step, as does the well standing valve 16.

Tubing elevators which are Well adapted to move the pump unit from the seated position on the anchor 14 to the raised positions shown in FIG. 3 are known in the art. Therefore, the disclosure of this means in FIG. 1 comprises a simple hydraulic cylinder 60 having a piston 61 connected to a hanger and sealing member 62 from which the macaroni 22 is suspended.

While the invention has been disclosed in conjunction with a specific form and disposition of the parts, it should be expressly understood that numerous modifications and changes may be made without departing from the spirit and scope of the appended claims.

What I claim is:

1. In a fluid actuated downwell pump installation including a well tubing in which a fluid actuated pump is seated and a separate string of smaller tubing within said first tubing, said first tubing being normally connected to receive power oil for said pump unit in the annulus around said separate tubing, and said separate tubing being normally connected to receive fluid produced by said pump unit, the improvement comprising means to open said separate tubing for the reception of a soluble clean-out plug, valve means at the surface to connect said separate tubing to receive power oil and said first tubing to exhaust, whereby contaminants are removed from the interior of said separate tubing by forcing said soluble plug down under the pressure of power oil, and normally closed valve means disposed adjacent said pump unit openable by pressure in said separate tubing in the direction of said first tubing to interconnect said first and separate tubing strings to bypass fluid and contaminants forced from said separate tubing by said soluble plug.

2. In a fluid actuated downwell pump installation including a well tubing in which a fluid actuated pump unit is seated and a separate string of smaller tubing within said first tubing, said pump unit being connected to said separate string of smaller tubing, said first tubing being normally connected to receive power oil from a pump into the annulus around said separate tubing, and said separate string of tubing being normally connected to receive fluid produced by said pump unit, the improvements comprising a jack means at the surface connected to raise said separate tubing in said first tubing and said pump unit from its seat while maintaining the flow of power oil in said first tubing, whereby power oil flows through said pump unit in a direction normally taken by pumped production fluid.

References Cited in the file of this patent UNITED STATES PATENTS 1,723,162 Harris Aug. 6, 1929 2,194,740 Coberly Mar. 26, 1940 2,230,830 Coberly Feb. 4, 1941 2,411,044 Landrum et al. Nov. 12, 1946 2,663,261 Gage Dec. 22, 1953 2,980,027 Dulaney Apr. 18, 1961

Claims (1)

1. IN A FLUID ACTUATED DOWNWELL PUMP INSTALLATION INCLUDING A WELL TUBING IN WHICH A FLUID ACTUATED PUMP IS SEATED AND A SEPARATE STRING OF SMALLER TUBING WITHIN SAID FIRST TUBING, SAID FIRST TUBING BEING NORMALLY CONNECTED TO RECEIVE POWER OIL FOR SAID PUMP UNIT IN THE ANNULUS AROUND SAID SEPARATE TUBING, AND SAID SEPARATE TUBING BEING NORMALLY CONNECTED TO RECEIVE FLUID PRODUCED BY SAID PUMP UNIT, THE IMPROVEMENT COMPRISING MEANS TO OPEN SAID SEPARATE TUBING FOR THE RECEPTION OF A SOLUBLE CLEAN-OUT PLUG, VALVE MEANS AT THE SURFACE TO CONNECT SAID SEPARATE TUBING TO RECEIVE POWER OIL AND SAID FIRST TUBING TO EXHAUST, WHEREBY CONTAMINANTS ARE REMOVED FROM THE INTERIOR OF SAID SEPARATE TUBING BY FORCING SAID SOLUBLE PLUG DOWN UNDER THE PRESSURE OF POWER OIL, AND NORMALLY CLOSED VALVE MEANS DISPOSED ADJACENT SAID PUMP UNIT OPENABLE BY PRESSURE IN SAID SEPARATE TUBING IN THE DIRECTION OF SAID FIRST TUBING TO

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