US2179620A - Method for well cleaning - Google Patents

Description

W. J. CRITES METHOD FOR WELL CLEANING Original Filed Jan. 2l, 1937 Fig. 4

v I I! x "Hi Illllll u. lll' INVENTOR WILBUR J. Crm-Es ATTORNEY touted MIETHIOD FOR WELL ClLEl Wilbur .1. Gritos, lesville, lllkla., assigner to Phillips Petroleum Company, a corporation oi Melaware 2 Claims.

This invention relates to improvements in well cleaning.

More specifically the invention relates to a method and apparatus for cleaning out bottom holes in wells operating with pumps.

In oil well pump installations, the present practice is to attach a screen to and directly below the standing valve assembly which is located at the bottom of the accumulation chamber of the pump. The purpose of this screen is to keep out larger particles of earth debris which might clog the pump. When there is a cave-in or a gradual accumulation of earth debris in the bottom hole,

oil cannot flow into the screen and the pump be- ]0 comes inoperative. It is then necessary to clean out the bottom hole either by removal of the tubing, pump, and screen and subsequent hailing or by backwashing through the screen perforations. Since removal of the tubing, pump, and screen is an expensive operation, the preferred method is backwashing. In the present invention instead of attempting merely to clean out the perforations in the screen as previously done, a suicient quantity of water or other suitable liquid is forced into the bottom hole to dilute the debris therein to a ovving consistency which when admitted to the-accumulation chamber through the standing valve will be further diluted by liquid retained there for that purpose to a consistency produceable by the pump.

The method and apparatus of this invention are readily applicable to a gas-lift device of the type disclosed by Stephens et al. in Patent 2,142,- 482 issued January 3, 1939. This application is a division of my copending application, Serial No. 121,688, filed January 21, 1937, entitled Method and apparatus for well cleaning. It is to be understood however that the invention is alsoapplicable to any well using a gas lift pump.

An important object of the invention is the provision of a method and apparatus for cleaning out the bottom hole in a well in an efficient manner.

A further object of the invention is the provision of a cleanout device for the bottom hole of a well which will not interfere with normal pumping operations.

A still further object of the invention is the provision of a cleanout device for the bottom hole of a Well which forms part of the pump assembly.

Other objects and advantages of the invention will become apparent during the course of the following description. In the accompanying drawing, forming a part of this specification, and in which like numerals designate like parts throughout the same,

Fig. 1 is a view partly in elevation and partly in section of a device embodying the invention,

Fig. 2 is a cross-sectional view taken on the 5 line 2-2 of Fig. 1,

Fig. 3 is a cross-sectional view taken on the line 3-3 of Fig; 1 and in which the valve springs have been omitted to simplify the showing,

Fig. 4 is a schematic showing of the device of 10 Fig. 1 in position in a bottom hole, and l Fig. 5 is a view in longitudinal section of another mbodiment of the lower section of the fitting.

In the drawing, wherein for the purposes of 15 illustration, is show'n a preferred embodiment of my invention, the numeral 6 designates generally a fitting formed for purposes of manufacture by an upper section 'I and a lower section 8. The sections meet at a ground joint 9 and are held 20 together by cap screws Il) in recesses I I. Upper section 1 is internally screw threaded at I2 and lower section 8 has an annular bore I3, screw threaded on both its cylindrical walls at I4 and I5. Engaging threads I4 is a tube I6 terminating 25 at its lower end in a standing valve I1 including valve seat I8 and a supporting element I9. Engaging threads I5 is a tubing 20 spaced from tubing I6 and terminating in a bull plug 2| having openings 22 forming a screen. Fitting 6 has pas- 30 sages 23 drilled through its side wall near the top closed by plugs 24. Each passage connects through a. port 25 with a bore 26 extending downwardly through the wall to a point adjacent the upper end of annular bore I3 with which it is in 35 communication by a port 21. In each bore 26 is a valve 28 closing port 25 by the action of a spring 29. Valve 28 is spaced from the walls of bore 26 by guides 30.

Fig. 4 shows the arrangement of the device in 40 operating position. A casing is shown at 3l cemented at 32 to the bore hole wall in the neighborhood of the producing formation. A tubing string 33 is connected at its lower end to a gaslift pump 34 having a discharge tube 35 and a 45 fluid pressure conduit 36 extending from its lower end. Discharge tube 35 extends upwardly through the pump to be connected to a ow string 3l which in turn continues upwardly to the surface of the ground. The space 38 between strings 50 33 and 31 is hermetically sealed above the ground and constitutes a uid pressure conduit to the gas-lift pump 34 from a uid pressure pipe 39 at the surface. Pipe 39 includes an intermitter 4I) and a control 'valve 4I. It is apparent from an 55` inspection of Fig. 4 that the device of the present invention constitutes a modified accumulation chamber for the gas-lift pump extending into bottom hole 42. A tube 43 depends from the lower end of pump 34 and is screw threaded into threads I2 of the fitting 6. Thus tube 43, tting 6, tubes I6 and 20 with valve `I1 and bull plug 2| form an accumulation chamber for pump 34 in which the lower part is formed of concentric, spaced receptacles, the inner one closed at the bottom by standing valve I1 and the outer one by bull plug 2I and the space in between these receptacles communicating with the interior of the accumulation chamber at fitting 6 when valves 28 are open.

In Fig. 5 a modification of fitting section 1 of Fig. 1 is shown wherein instead of being integral throughout, the section is shown formed of two telescoping machined cylinders 1-A and 1-B which may be a more desirable construction for purposes of manufacture. In this form threads I4' and l5' are cut in cylinders 1-A and 1-B respectively before they are assembled and to such a depth that on assembly an annular recess I3' is formed. A lip 'I-C is formed on cylinder 1-A to positively position the two cylinders with respect to one another.

As is well known to those skilled in the art, the gas-lift pump applies gas under pressure to the surface of the oil in the accumulation chamber forcing the oil up discharge tube 35 and flow string 31. Springs 29 are so designed that valves 28 are not opened by the usual operating pressures in the accumulation chamber. When the oil level in the accumulation chamber has been lowered to a pointnear the lower end of discharge tube 35, the gas pressure supplied to pump 34 through fluid conduit 31 is cut 01T by intermitter 40 and the pump operates to exhaust the gas under pressure from the accumulation chamber, allowing the oil in the bottom hole to ow into the accumulation chamber, filling it again for a succeeding pressure stage, initiated by the action of the intermitter in reinstating the gas pressure. However, when rock and dirt debris accumulates in the bottom hole, either from natural disintegration of its walls or from a cavein thereof, the openings 22 in bull plug 2| become stopped preventing the oil in the bottom hole from flowing into the accumulation chamber. The operation of the pump must then be stopped and the bottom hole cleaned out. Control valve 4I is closed cutting off the gas pressure from space 38. Water or other suitable fluid is admitted to space 38 in suiicient quantity to cover port 23 in the accumulation chamber by the amount of liquid desired to be forced into the bottom hole as herein later more specifically described. Gas at a pressure higher than the usual pumping pressures is then applied to space 38, the same pressure being applied to ow string 31. The latter step prevents the pump from operating. It can readily be seen that all the liquid above passage 23 will be forced past valve 28, down through the conduit formed by bores 26 and the annular space between the inner and outer receptacles, to the openings in the bull plug and into the bottom hole 42. theapplication of' high 'pressure gas can be continued to agitate the mixture of mud in the bottom hole. Upon relieving the pressure on space 38 and flow string 31, the gas in the accumulation chamber above port 23 will be exhausted by the operation of the pump. The mud produced outside the bull plug will flow into the bull plug and up through the standing valve where it will be further diluted by the liquid remaining in the accumulation chamber below passage 23, thus reducing its consistency to a point at which it can be more easily handled by the gas-lift pump. The amount of liquid required will differ with the amount and character of the material blocking flow of oil in the bottom hole. It should be a sulcient quantity to achieve the degree of consistency of mud in the accumulation chamber mentioned above. It may be necessary to repeat the entire'operation several times to restore full flow of the oil.

It is to be understood that the form of my invention, herewith shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size, and arrangements of parts may be resorted to without departing from the spirit of my invention, or the scope of the appended claims.

I claim:

l. The method of cleaning out bottom holes in wells which are stopped by earth debris, wherein an accumulation chamber for a pump terminates in said bottom hole, comprising the steps of admitting liquid under pressure into said bottom hole in quantity suicient to form a owable mixture of said debris and said liquid, while retaining a quantity of liquid in said accumulation chamber, releasing said pressure whereby said mixture flows into said accumulation chamber, said liquid in said accumulationvchamber diluting said mixture to a consistency whereby said mixture can be pumped.

2. The method of cleaning out bottom holes in wells which are stopped by earth debris, wherein an accumulation chamber for a pump terminates in said bottom hole, comprising the steps of admitting liquid under pressure into said bottom hole in quantity sufficient to form a flow,- able mixture of said debris and said liquid, while retaining a quantity of liquid in said accumulation chamber, agitating said mixture, releasing said pressure whereby said mixture flows into said accumulation chamber, said liquid in said accumulation chamber diluting said mixture to a consistency whereby said mixture can be pumped.

WILBUR J. CRITES.

If desirable as in the case of cave-ins

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