US2259429A

US2259429A - Method of treating wells

Info

Publication number: US2259429A
Application number: US287788A
Authority: US
Inventors: Drury M Simmons
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1939-08-01
Filing date: 1939-08-01
Publication date: 1941-10-14
Anticipated expiration: 1958-10-14

Description

CCL 14 194l D.. M. slMMoNs Filed Aug. l, 1939 ff f 'Wa/ /Lmi 2555-2-1- El METHOD TREATING WELLS INVENTOR ra/y M .immo/7.5

c/ ATTORNEYS .i Patented Oct. 14, 1941 METHOD OF TREATING WELLS Drury'M. Simmons, Shreveport, La., assigner to The Dow Chemical Company, Midland, Mich., a corporation of Michigan Application August 1, 1939, Serial No. 287,788

(Cl. 16B-21) 4 Claims.

The invention relates to an improvement in the use of fluid agents, particularly acids, for the treatment of deep wells, such as those yielding oil or gas, to increase the production therefrom.

In the treatment of wells with acids it has beenqthe practice, as described in U. S. Patent No. 1,916,122, first to introduce into the well a quantity of a liquid or solution that is substan' tially inactive toward the earth formation, which liquid is of a higher specific gravityi than the acid, so as to fill the voids in the earth underlying the producing stratum. By such means the acid, when subsequently introduced, is prevented from draining away from the stratum to be treated and spent ineffectively or harmfully on the non-productive earth below the producing stratum. Such method however, has certain disadvantages which clearly limit its usefulness. For example, in some wells the underlying formation is readily permeable to such liquids and the lattermay flow readily into the underlying earth, so that the acid cannot be maintained in the well in the desired position. In some instances, as wherein the underlying formation is,y producing water, the acid may increase the per' meability of the water producing formation to the extent that the water inflow kills the well by preventing the inflow of oil thereinto. An`r other disadvantage is that when fluid pressure is applied to the acid, as is usually done to force it into the stratum to be treated, the additional pressure tends to cause the supporting fluid to be' displaced into the formation even though the formation is not readily permeable, thereby permitting the acid to act upon non-productive earth or rocobon a stratum that may greatly harm the producing capacity of the well.

The principal object of the present invention is to provide a means of introducing a iiuid treating agent into a well at a desired level While preventing its infiltration into a stratum located at a lower level. Still further objects and advantages of the invention will appear as the description proceeds.

I have discovered that these and other objects may be attained by introducing the fluid treating agent into the well through a conduit, the lower open end of which is located adjacent the producing stratum, while introducing an inac tive liquid into the Well through a second con' duit, the lower open end of which is located be-' low that of the first conduit.

By the term inactive liquid used herein and in the appended claims is meant a liquid such reacting with the formation or constituents thereof, and preferably one that is immiscible with the treating agent being employed. As an example, when acid is being employed as the treating agent, crude oil may be suitably employed as the inactive liquid.

The invention then consists in the method hereinafter fully described and particularly pointed out in the claims, the accompanying drawing and following description setting forth in detail a mode of carrying out the invention, such mode illustrating however but one of the various ways in which the principle of the invention may be carried out.

The single figure of the accompanying drawing is a diagrammatic view in vertical section of an oil well suitably equipped for. a treatment in accordance with the invention. As shown, the upper portion I of the well bore is cased with metal pipe 2 to a point 3 a short distance above the producing stratum. The lower portion of the well bore 4 penetrates an oil producing stratum 5 and ends in stratum 6 from which water encroachment is occurring. Above the ground level, the well is shown equipped with a conventional casing head 1, through which conduit 8, in this instance the well tubing, extends into the well bore to a point 9 adjacent the oil producing stratum 5. Pipes I0 and I I, suitably controlled by valves I2 and I3, communicate with the well which water encroachment is occurring. The

second conduit is sealed to the well tubing above the ground level as by means of swagenipple I6. Valve I1, suitably connected to the smaller conduit I4 serves as a means of controlling the introduction of fluid through this conduit. The

portion of the well bore adjacent the water stratum is shown filled with an inactive liquid, such as oil I8, while the portion of the bore adjacent the oil stratum is shown filled with acid I9. The remainder of the well bore above the oil stratum is shown filled with a pressuring fiuid, such as oil 20, which serves to control the level to which the acid may rise in the well bore.

In carrying out the method of the invention in an oil well having its productive stratum disposed in calcareous earth or rock, wherein acid is to be employed to facilitate the production therefrom, the well is first filled with oil to render it hydrostatically controllable. This may be acas oil, water, or the like, which is incapable of complished by pumping oil into the well through @cui pipe II while valves I2 and I3 are maintained in an open posi-tion. After the well has been filled with oil, the acid solution is started into the well through pipe I I communicating with the well tubing 8, while oil is allowed to escape at the casing head through pipe I0. After a suicient quantity of acid has been introduced to fill the annular space between the tubing 8 and conduit I4, valve I2 controlling pipe I0 is closed and a quantity of inactive liquid, such as, for ex; ample, oil, is started into the well through conduit I4. During the introduction of the desired amount of acid, oil or the like is continuously pumped into the well through the conduit I4 and forced into the water stratum 6, thereby preventing the acid from reaching and attacking this formation. After the desired quantity of acid has been introduced, the well may be closed in to allow the acid to spend itself. The smaller conduit may then be removed from the well and the spent acid 'bailed or pumped from the well,

after which it may be put into production.

By carrying out the treatment in the foregoing manner improved results are obtained as regards directing the fluid treating agent into the desired 'section of the formation, since by bringing about the introduction of the inactive liquid at a point below the point of introduction of the treating fluid, assurance is had that the inactive liquid is entering the lower portion of the formation while the treating fluid is conned to the upper portion of the formation.

` Although it is preferable to employ an inactive liquid which is immiscible with the treating fluid, inactive liquids of the type which are miscible with the treating agent may also be employed. For example, in carrying out an acid treatment although oil is preferably used, water may be employed as the inactive liquid, since any mixing that occurs when the two are pumped into the formation does not detract appreciably from the eifectiveness of the acid solution.

AThe rate at which the two liquids should be introduced relative to one another may be varied quite widely, although it is usually preferable to introduce the inactive liquid at substantially the same rate as the treating liquid or uid. However, this rate is in turn dependent upon the extent of the formation into which it is desired to prevent the entrance of fluid treating agent relative to the extent of the formation yto be treated.

Although the method has been described with particular reference to carrying out the acid treatment of a well, it is to be understood that the method is also applicable to carrying out a treatment with other agents, such as parain solvents, chemical plugging agents, and the like, which are in uid form.

Other modes of applying the principle of my invention may be employed instead of those explained, change being made as regards the meth.. od herein disclosed, provided the step or steps stated by any of the following claims or the equivalent of such stated step or steps be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a method of treating a well with a fluid treating agent, said well being equipped with the usual casing and well tubing, the steps which consist in introducing the fluid treating agent into the well through the well tubing, the lower open end of which is located adjacent the formation to be treated, while introducing an inactive liquid into the well through a second tubing disposed within the casing and having its lower open end located below that of the well tubing, and forcing both the fluid treating agent and the inactive liquid into the formation while applying pressure on the fluid treating agent through the casing to prevent the upward displacement in the well of the fluid treating agent as it is being forced into the formation.

2. In a method of treating with hydrochloric acid a well having its producing formation 1ocated in calcareous earth or rock formation, said well being equipped with the usual casing and well tubing, the steps which consist in introducing the acid into the well through the well tubing, the lower open end of which is located adjacent the formation to be treated, while introducing oil into the well through a second tubing disposed within the well tubing and having its lower open end located below that of the well tubing, and forcing both the hydrochloric acid and the oil into the formation while applying pressure upon the acid through the casing to prevent its upward displacement in the well bore as it is being forced into the formation.

3. In a method of treating with hydrochloric acid a well having its producing formation disposed in a calcareous earth or rock formation, said well being equipped with the usual casing and well tubing, the steps which consist in introducing the acid into the well through the well tubing, the lower open end of which is located adjacent the formation to be treated while introducing water into the well through a second tubing disposed within the well tubing and having its lower open end located below that of the well tubing, and forcing both the hydrochloric acid and the water into the formation while applying pressure upon the acid through the casing to prevent its upward displacement in the well bore as it is being forced into the formation.

4. In a method of treating a well with a fluid treating agent, the steps which consist in introducing the fluid treating agent into the well through a conduit disposed within the well bore and having its open end adjacent the formation to be treated, while introducing an inactive liquid into the well through a second conduit disposed within the well bore and having its lower open end located below that of the rst conduit and controlling the rate of introduction of the inactive liquid so as to conduct the uid treating agent to the desired portion of the formation.

DRURY M. SIMMONS.