US3442329A - Paraffin valve for oil wells - Google Patents

Description

May 6, 1969 A. L. WALDRON PARAFFIN VALVE FOR OIL WELLS sheet Original Filed July 28, 1965 mvEmon: ALTON L. WALDRON ATT Y5.

May 6, 1969 A. L. WALDRON 3,442,329

PARAFFIN VALVE FOR OIL WELLS Original Filed July 28, 1965 ATTYS.

United States Patent 3,442,329 PARAFFIN VALVE FOR OIL WELLS Alton L. Waldron, Annapolis, Md., assignor to Hydrasearch (30., Inc., Annapolis, Md., a corporation of Maryland Original application July 28, 1965, Ser. No. 475,421, now Patent No. 3,361,205, dated Jan. 2, 1968. Divided and this application Sept. 1, 1967, Ser. No. 678,129

Int. Cl. E21b 43/00 US. Cl. 166-224 3 Claims ABSTRACT OF THE DISCLOSURE contained therein biased valve means which seals the inlet means from the outlet means until a predetermined pressure is reached whereupon fluid communication is obtained between the inlet and the outlet means. Positioned in the valve body is engagement means for holding the valve means in the open position until a predetermined lower pressure is reached whereupon the valve means closes off the inlet terminating fluid communication between the inlet and outlet.

This is a division of application Ser. No. 475,421, filed on July 28, 1965, now Patent No. 3,361,205.

The present invention relates to apparatus and a method for using the same in oil wells and more particularly to a valve assembly and the method of using the same which permits the treating of a well bore at predetermined regions for removing parafiin deposits accumulated therein.

When an oil well has been in operation for a period of time, the subterranean or reservoir pressure causing a flow of petroleum to the surface gradually decreases, to the point that it becomes necessary to recover the remainder of the oil in the subterranean cavern by a pumping operation. When recovering the petroleum by pumping, paraflin deposits in the tubing string of the pumping line, usually at a predetermined and calculable level, which deleteriously affects, curtails and even halts the pumping action. When this condition occurs, and in some wells which pump petroleum having a high paraflin content the condition occurs repeatedly at relatively short intervals, it is normally necessary to pull the tubing string for the purpose of cleaning, or to resort to laborious operations for cleaning the parafiin deposits while the tubing string is in position. In either case the cleaning of the tubing string by the methods abovedescribed, results in lengthy shut-downs with, of course, a concurrent financial loss,

The prior art has exhibited various means, including valve assemblies placed in the tubing string, for permitting the placement in the so-called palafiin region (i.e. the depth at which pa-raflin accumulations occur) of a solvent which will dissolve the paraflin deposits and permit further use of the well without removing the tubing string or the sucker rod interiorly mounted therein. For example, in the Abbott Patent No. 3,016,094 which issued on Jan. 9, 1962, this valve assembly requires abovesurface extensions reaching down to the valve assembly in order to effectuate a closing off of the tubing below the paraflin region. Because of the risk of corrosion by small quantities of water and sulphur in the petroleum, lvalves of this type have proved unacceptable over long periods of unattended service.

In view of the above, it is a principal object of the present invention to provide a valve assembly for placement in the tubing string whereby paraffin deposits thus occurring may be quickly and easily removed without the necessity for pulling the tubing string or sucker rod, and with a minimum delay in the operation of the Well.

Another object of the present invention is to provide a valve assembly whereby a parafiin-removing agent such as a solvent may be efiectively introduced into the tubing string at the region of paraflin deposits for effectively and economically removing the latter and restoring the production of the well.

Still another object of the present invention is to pro vide a valve which is automatically operated and needs no connecting apparatus extending from the paraflin region to the surface.

Still another object of the present invention is to provide a valve assembly which may be placed in any part of the tubing string wherein the predetermined paraflin region occurs, and which valve may be adjusted to operate at the desired depth in the tubing string.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawings in which:

FIG. 1 is a fragmentary side elevation view partially in section illustrating an oil well having a valve constructed in accordance with the present invention, positioned therein;

FIG. 2 is an enlarged fragmentary sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a fragmentary sectional view of a portion of the exterior casing of the valve constructed in accordance with the present invention and illustrating paraflin deposits above the valve;

FIG. 4 is a sectional view taken along line 44 of FIG. 2 and as if FIG. 2 were not in section;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 2 and as if FIG. 2 were not in section;

FIG. 6 is a sectional view taken along line 66 of FIG 5;

FIG. 7 is a fragmentary sectional view similar to that illustrated in FIG. 5 with the valve of the present invention in another position than that shown in FIG. 5; and

FIG. 8 is a fragmentary sectional view taken along line 8-8 of FIG. 7.

Referring now to the drawings, and especially FIG. 1 thereof, a casing 10 having an upper casing head or flange 11 is shown inserted in a well bore 12 and having a lower terminus in a subterranean oil reservoir 13. Interiorly of the casing 10 is a tubing string 14, the lower end of which is connected to a conventional reciprocating pump 15 which, in the present instance, is positioned in the oil reservoir 13. At the upper end of the tubing string 14 is a tubing head 16, an oil discharge pipe 17, and a solvent and air bleeder pipe 18 with valves 17a and 18a respectively therein. Interiorly of the tubing string 14 and extending substantially coaxially therewith is a sucker rod 19 which sucker rod connects the tubing head 16 with the reciprocating pump 15 and permits Operation of the pump in a conventional manner.

In accordance with the invention, a valve assembly 20 is positioned in the tubing string 14 below the predetermined and calculable area of accumulation of the paraflin interiorly of the tubing string 14, whereby upon closing off of the oil outlet pipe 17 by the valve 17a and operating of the reciprocatory pump 15 with the valve 17a closed, a sufficient pressure is built up interiorly of the valve which automatically dumps the oil, or a certain set portion thereof, in the tubing string above the valve into the space intermediate the tubing string 14 and the casing 10. The pump 15 is then shut down. Upon the release of the oil in the tubing string superimposed above the valve 20, or any predetermined portion as preset, the valve automatically closes, trapping a certain amount of oil above the valve in the tubing string. At this point the valve 18a, which has associated therewith an air bleeder check valve (not shown) to admit atmospheric pressure into the tubing string above the oil as it is dumped, is opened and a solvent or the like placed into the tubing string 14. In a short period of time the solvent causes dissolving of the paraffin, tars or basic sediments which have been deposited and built up interiorly of the tubing and above the valve 20.

To this end, and as best illustrated in FIGS. 2, 4, 5, and 6, the valve 20 is provided with tubing coupling means 21 and 22 for mounting a tubular body 23 in the tubing string while permitting fluid communication therethrough as by the bore 24 interiorly of the body 23.

The operating portion of the valve which permits dumping of the oil in the tubing string upon a predetermined overpressure being reached therein, and which permits closing off of the valve upon dumping of the fluid into the casing and at a predetermined pressure, is best shown in FIGS. 2 and 5. As shown in FIG. 2, the body 23 is provided with a bore 25 having an oil inlet 26 at one end thereof which permits communication of the bore with the interior of the tubing via the bore 25 of the valve body 23. Mounted interiorly of the bore 25 is a piston 27 and at the lower end thereof a valve plug or disc 28 with, in the present instance, a conical seating portion 29 for seating in an extension 30 of the inlet 26. As shown in FIG. 5, the seating cross sectional area of the valve plug or disc 28, designated A-1 for purposes of identification, is less than the cross sectional area of the piston 27, which area is designated A2. Aligned with the piston 27 and normally biasing the disc 28 into the closed position is biasing means, in the present instance a main piston spring 31, the upper portion of which abuts an adjusting screw 32. (See FIG. 2.) As illustrated in FIG. 5, the main piston 27 is provided with a shoulder stop 33 which prevents, upon the piston being displaced vertically in the bore 25, vertical overriding of the piston. Upon sufficient pressure being applied to the inlet 26 and thus the area A-1 of the plug 29, the plug moves off its seat and the pressure at the inlet reaches the larger area A2, thus causing the piston to raise against the spring.

In order to dump the oil contained in the tubing string 11 above the valve 20 and to hold the piston open against the spring 31, outlet means for dumping the oil in the tubing string is provided to dump the oil into the casing while piston engaging means are provided to engage and hold the piston 27 until a predetermined low pressure is reached at which time the piston is permitted to move downwardly and the plug 29 to reseat in the seat of the inlet extension 30. To this end, and as best illustrated in FIGS. 6, 7, and 8, at least one outlet means, in the present instance two outlets 34 are provided which permit communication, when the piston 27 is in its raised or elevated position, with the bore 25 and thus the inlet 26, the outlets connecting and permitting the dumping of the oil in the tubing string above the valve into the space between the tubing 14 and the casing 10.

To permit the piston to be held in the elevated position to allow communication between the inlet 26 and the outlets 34 until a preset low pressure corresponding to a fixed amount of oil remaining in the tubing string is left, the piston 27 is provided with engagement means, in the present instance an annular groove 35 which permits engagement of pressure responsive detent means 36, located on either side of the piston and which engage the engagement means and hold the piston in an elevated position. As illustrated in FIG. 6, each of the detent means 36 comprises a ball 37 lying in rubbing engagement with the piston 27, a ball piston 38 and a grease-filled conduit 39 fitted with a diaphragm 40. The opposite side of the diaphragm communicates with the bore 24 of the valve 20 thus causing the movement of the ball pistons to be responsive to changes in internal pressure in the tubular valve body 23. The purpose in filling the conduit 39 with grease instead of allowing direct communication of the oil with the base of the ball pistons 38 is to avoid, as much as possible, corrosive contact with the oil, which may contain sulphur and water and other impurities. Such impurities, because of their corrosive effect, may deleteriously affect the operation of the valve. As illustrated in FIGS. 7 and 8, as the piston 27 raises against the spring pressure 31, the outlets 34 permit dumping of the oil into the casing 10, while the pressure existing at the inlets 41, causes inward deflection of the diaphragm and thus of the ball pistons. This causes placement of the balls into the annular groove 35, when the piston 27 raises to a position wherein the groove aligns with the balls. At a predetermined pressure, depending upon the setting of the detent means 36, the spring pressure of the spring 31 will overcome the piston 27 and the detent means 36 and permit the piston 27 to reseat in the inlet extension 30.

It should be kept in mind that each oil well is different and that the valve as heretofore described may be placed in the tubing string anywhere from 500 to 5,000 feet below the earths surface. In addition, it has been found that the valve spring pressures should be designed so that an overpressure of from 200 to 350 p.s.i. imposed on the static head in the tubing string 14 will cause the valve to operate While a low pressure of approximately 50 to 200 psi. will cause the valve to reseat. In any event, the valve may be set to close with from to 600 feet of oil remaining in the tubing string as the low pressure setting is proportional to the depth at which the valve is placed and inversely as the weight of the pumped oil.

As will be known to those skilled in the art, the areas and spring pressures of the various components of the valve 20 as heretofor described may vary from well to well and the depth at which the valve 20 is placed. Generally, it has been found that a ratio between the areas A1 and A2 of approximately 1:6 or a value of A4 equal to 16 to 20% of A2 achieves the desired result, above described, and which provides parameters for spring compression design. Obviously, the adjustment of the spring compression by the adjusting screw 32 is dependent primarily upon the location of the lower portion or bottom of the parafiin zone and the specific gravity of the oil being pumped.

In practice, the valve is preferably placed at a depth of 400 to 500 feet below the bottom of the paraffin zone and thus the desired valve pressure setting will be the static pressure at a point 400 to 500 feet below this region and may be determined roughly from the following equation:

Valve pressure setting in p.s.i.=(D.+400) S.G. .433

where D=valve installation depth from ground level. S.G.=specific gravity of the petroleum.

Thus for example if the lowest point at which paarffin accumulates is 1500 feet below the surface, and assuming the valve is positioned in the tubing string 2000 feet below the surface level, the valve should be set to open at approximately 1000 to 1200 psi If the valve is set to close at between and psi, approximately 200 to 280 feet of oil would be located in the tubing string above the valve. Thereafter of course the solvent would be applied and allowed to remain for a sufficient period to dissolve the paraffin and then pump it out.

Thus a novel valve assembly is provided by the present invention for placement in the tubing string which valve permits the removing of paraffin deposits accumulated in the string without the necessity for pulling the tubing string or sucker rod for cleaning, thus providing the economic gain of minimum downtime. In addition, a novel method of dissolving the paraflin in the paraflin region is provided wherein a predetermined amount of oil above the valve may be dumped into the casing for placement in the tubing string of paraflin dissolving solvents.

Although the invention has been described with a certain degree of particularity, it is understood that the present disclosure ,has been made only by way of example and that numerous changes in the details of construction, method of operation, and the combination and arrangement of parts may be made without departing fromthe spirit and the scope of the invention as hereinafter claimed.

What is claimed is: i 1. A valve for permitting the dumping of at least a portion of the liquid in a well having a tubing string 'positioned interiorly of a well casing; said valve comprising a valve body for positioning in said tubing string, said valve having means for permitting fluid communication therethrough; fluid inlet means in said valve communicative with the interior of said tubing string and fluid outlet means communicative with said well casing; bore means connecting said inlet and said outlet means, and a pressure responsive and biased valve means in said bdre sealing said inlet means from said outlet means until a first predetermined pressure is reached whereby fluid communication is obtained between said inlet and said outlet means, said pressure responsive and biased valve means including a piston having a disc at one end thereof for sealing said inlet means and a biasing spring for keeping said piston against said inlet means, and engagement means for holding said valve means in the open position until a second predetermined pressure lower than said first predetermined pressure is reached whereby said valve means is biased closed, said engagement means including detent means having a ball poistioned for rubbing engagement with said piston, a ball piston, conduit means leading from said ball piston to the interior of said valve body to provide pressure responsive communication with the fluid in said valve body, means on said piston for engagement with said ball and a diaphragm transversely positioned in said conduit means, the portion of said conduit means between said diaphragm and said ball piston being filled with a separate fluid from the fluid on the opposite side of said diaphragm.

2. A valve in accordance with claim 1 wherein said means on said piston for engagement with said ball comprises an annular groove.

3. A valve for permitting the removal of parafln deposits in oil wells having a tubing string positioned in a well casing; said valve comprising a tubular valve body having coupling means for mounting in said tubing string and permitting fluid communication therethrough; a valve assembly in said body including an upstanding bore having piston means mounted therein; said bore having an inlet communicative with the interior of said tubing string adjacent one end thereof and biasing means positioned to keep said piston sealed against the inlet during normal pumping operations; outlet means in said bore connecting said bore with said casing and positioned so as to permit a flow of oil into said casing upon said piston being displaced from the inlet; and piston engagement means to engage and hold the piston away from the inlet upon said piston being displaced, said engagement means including detent means having a ball positioned for rubbing engagement with said piston, a ball piston, conduit means leading from said ball piston to the interior of said valve body to provide pressure responsive communication with the fluid in said valve body, a diaphragm transversely positioned in said conduit, the portion of said conduit between said diaphragm and said ball piston being filled with a separate fluid from the fluid on the opposite side of said diaphragm, and means on said piston for engagement with said ball, said engagement means being responsive to a pressure decrease in said tubing string whereby upon a predetermined decrease in pressure said piston means closes off said inlet.

References Cited UNITED STATES PATENTS 2,431,769 12/1947 Parker.

2,651,319 9/1953 Cummings 137-155 2,795,238 6/1957 Hirsch 25194 X 3,018,786 1/1962 Stratton 137118 3,107,498 10/1963 Messer 251-94 X 3,169,587 2/1965 Hub-bard 166224 X 3,334,697 8/1967 Edwards et al. 166224 X CHARLES E. OCONNELL, Primary Examiner. JAN A. CALVERT, Assistant Examiner.

U.S. Cl. X.R. 251-94; 137118,47l

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