US3548946A

US3548946A - Apparatus and method for liquid introduction in oil wells

Info

Publication number: US3548946A
Application number: US807745A
Authority: US
Inventors: Charles J Engle
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1969-03-17
Filing date: 1969-03-17
Publication date: 1970-12-22
Anticipated expiration: 1987-12-22

Description

United States Patent [56] References Cited UNITED STATES PATENTS [72] lnventor CharlesJ.Engle Bartlesville, Okla. [21] AppLNo. 807,745

8/1968 Littleetal. 3,414,057 l2/l968 Harbison.................

O m m .mmm ZvB 057 555 999 111 Ill 1131 1 1 398 77 042 30 222 [22] Filed Mar. 17, 1969 [45] Patented Dec. 22, 1970 [73] Assignee Phillips Petroleum Company a corporation of Delaware Primary Examiner-Marvin A. Champion Assistant Examiner-Ian A. Calvert Attorney-Young and Quigg ABSTRACT: Chemical treatment of oil wells is effected by placing the particular chemical in the well bore at the desired depth by the use of subsurface apparatus comprising a hollow sucker rod, the core of which is in communication with the well bore through the production tubing. The communication ports are isolated by packing means from the produced fluid flowing upwardly through the production tubing. The produced fluid bypasses the packed off area of the production tubing through a suitable crossover flow device.

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EOW M Mn m ww M Ans PR PM Amoo U mm M H UN 5 H mm PATENT ED 115x122 I970 INVENTOR. C. J. ENGLE 7 7 9? A T TORNEVS APPARATUS AND METHOD FOR LIQUID INTRODUCTION IN OIL WELLS This invention relates to a method and apparatus for introducing a liquid into an oil well through a hollow sucker rod.

The introducing of various liquids into oil wells in order to increase production is known in the art. Accordingly, modern production technology recognizes the value of introducing defoaming agents, slurries, fluid cements, water for water flooding, combustion supporting gas for tire flooding, and the like. The production of foam in the well requires the introduction of a defoaming agent because the oil well pumping apparatus relies for operability on the incompressibility of the produced crude. Thus, when foam exists in the crude, the incompressible nature of the produced stream is partly or wholly destroyed and the downhole recovery pump either functions at greatly reduced efficiency or completely fails to raise the produced stream to the uphole location.

The reason foam exists in the produced crude is unknown; however, one theory suggests that foaming occurs as a result of the release of CO, and other dissolved gases as the pressure on the crude drops from formation pressure to bottom hole pressure.

To a certain extent all reservoirs contain dissolved gases and foaming can become a significant production-problem in any reservoir and particularly in reservoirs that-have been subjected to an in situ combustion secondary recovery technique.

According to one typical type of insitu combustion operation a high temperature zone is established in the oil-bearing region of a reservoir around a well bore. Suitable heating means for'establishing a high temperature zone within the formation can comprise an electrical heating device or a gas fired bottom hole igniter or heater. Upon introducing a com bustion-supporting or an oxygen-containing gas such as air into the heated formation via the well bore a high temperature combustion zone'i's created by the reaction between the oxygen and combustible residues within the high temperature zone of the oil-bearing regions. Upon continued introduction of the combustion-supporting gas this high temperature zone will commence to move into the formation outwardly from the well bore.

The combustion products of the combustion are primarily CO and H andat the elevated pressures existing in subterranean reservoirs much of the large volume of CO is dissolved in the crude and subsequently released when the pressure on the crude drops to downhole pressure during recovery. Thus, foaming is even a greater problem in reservoirs subjected to in situ combustion andin the case of low gravity, viscous crudes that produce a very stable foam, such as the'Morichal crudes from Venezuela and certain of those'in the United States, the problem becomes acute.

Since the foam is thought to be produced in the oil bearing region of the well when the pressure .on the crude is reduced, a problem exists in placing the defoamingagent in the precise location where the foam is produced. If the defoaming agent is merely poured in the top of the well, it can become flocculated by the action of the upcoming produced gas and consequently fail to function. Even if the defoamer reaches the downhole location, it can form a layer on top of the column of crude in the well and fails to function because it is on top of the column instead of farther down into the column where the crude flows out of formation and into the bore hole and produces foam.

Thus, this invention represents an improvement over the prior art in that a liquid, and in a preferred embodiment a defoaming agent, can be introduced into the oil bearing region of a producing well through a hollow sucker rod and in another embodiment can be introduced into the region where the crude flows out of the formation and into the bore hole.

In one embodiment of .this invention, an apparatus is provided for introducing a liquid into the oil bearing region of a producing cased well comprising a hollow sucker rod with a passageway from the exterior to the hollow region. In another embodiment of this invention, a length oftube is positioned in a casedwell, a reciprocating pumping-means is positioned within the oil bearing region of the cased well and .a hollow sucker rod is operably attached to the reciprocal pumping means. First and second packing means are positioned respectively uphole and downhole from said sucker rod passageway slidably sealing said sucker rod to said tubing and thus forming an annular chamber. Additionally, means are provided to conduct said introduced liquid from the annular chamber to the oil bearing region, and bypass means are provided so the reciprocal pumping means can pump the produced fluid around the annular chamber and up the annular passageway between the tubing and sucker rod. In one still further em? bodiment of the invention, a closure is provided between the tubing and casing and a means positioned through said closure to communicate produced gas upward through the closure. In one still further embodiment of the invention, a closure means is positioned downhole from the inlet of the pumping means and the tubing contains a passageway positioned uphole from said closure and downhole from said pumping inlet. In one additional embodiment the means to conduct the introduced liquid from the annular passageway to the oil bearing region comprises a means to conduct said liquid downhole from said closure and the introduced liquid comprises a defoaming agent. In one still further embodiment of the invention, the means to communicate produced gas up through said closure comprises a first tube and the means to conduct fluid from said annular chamber to the oil bearing region comprises a second tube annularly positioned within said first tube.

One object of this invention is to providemethod and apparatus for introducing liquid into the oil bearing region of an oil well through a hollow sucker rod. Another object of this invention is to prevent the formation of foam within the oil hearing region of a producing well. Another object of this invention is to introduce a defoaming agent directly into the oil bearing region of a producing well. Other objects, advantages and features of this invention will be readily apparent to those skilled in the art from the following description, drawings, and appended claims.

The attached FIG. represents a portion of a profile view in partial cross section of ,a cased producing well incorporating established by methods well known in the artpenetrating a subterranean oil bearing formation thus forming an oil bearing region within the bore hole. The bore hole is then cased by a casing 5 and perforated so as to form passageways between the oil bearing formation and the bore hole. The pressure differential between the oil bearing formation and the bore hole causes crude to flow from the oil bearing formation through passageways l0 and fonn a column of crude in the bore hole. A length of tubing is then positioned within the bore hole. Tubing 20 contains a valve 35, bypass means 25, and a means to conduct an introduced liquid into the oil bearing region. A hollow sucker rod 36 is then positioned within said tubing connected to a pumping cylinder 40 containing a valve 45. Tubing 20, valve 35, pumping cylinder 40 and valve cooperate to comprise a reciprocal pumping means when actuated by sucker rod 36. The sucker rod 36 contains a passageway from the exterior to the hollow portion of the sucker rod. Sucker rod 36 is slidably sealed for reciprocating movement within said tubing 20 by packing means and packing means 60, thus forming an annular chamber between the closures. In an additional embodiment, packing means seals tubing 20 within casing 5 so as to provide a reservoir below packing means 70 in which the defoaming agent can be inserted and isolated so as to intimately admix with the foaming crude. I

Packing means 70 can be located at any distance up or downhole in the column; however,packing means 70 must be equipped with a means to communicate produced gas upward through said closure. If the top-of column 15 is below packing means 70 satisfactory results can be achieved, although in a preferred embodiment packing means '70 is below the top of column 15.

from the annular chamber 653a more desirable'result is achieved by incorporating packing means 70 into the inven-.

tion and introducing the liquid downhole from packing means 70 through liquid introduction means 30. In the preferred embodiment where the liquid is a defoaming agent this places the defoaming agent in the precise location where the foam is thought to form and greatly increases the defoaming action. If packing means 70 is not used satisfactory results can still be obtained, particularly when the top of the column of crude 15 is above the passageway from the annular chamber 65 into the bore hole and perforations extend uphole to the vicinity of the annular chamber.

N In a preferred embodiment of the invention, the packing means 70 is positioned downhole from inlets 85 through said tube 20. If inlets 85 are not provided in tubing 20, a pressure differential is created across packing means 70 because-the gas exiting through means 75 necessarily carries out quantities of liquid which will accumulate above packing means 70 and produce an extremely heavy column of: liquid above packing means 70. Althoughthe invention will operate in this manner, it is desiredto provide passageways 85 so the pressure in the column of crude 15 above packing means 70'will be substantially similar to that below packing means 70. In a preferred embodiment, the means to conduct the introduced liquid from the annular chamber to the oil bearing region comprises a first tube and the means to communicate produced gas upward through said packing means 70 comprises-an annularly positioned tube 75.

Departing from the structure of the invention and focusing attention on the operation of the invention, sucker rod 36 is reciprocally driven by suitable uphole means while cylinder 40 and valve 45 cooperate with tube 20 and valve 35 so as to transport crude from the column of crude 15 up the annular region above cylinder 40 between tubing 20 and sucker rod 36.- Subsequently the produced fluid is conducted through bypass means 25 and up the annular region between'tube 20 and sucker rod 36 to an uphole location where it is recovered and subjected to further processing steps. The gas produced by the practice of this invention flows up the annular region between tubing 20 and casing and is recovered and processed. In the embodiment where packing means 70 is utilized, the gas that is produced below packing means 70 flows through means 75 and subsequently to the uphole location.

According to the operation of this invention, the liquid, which can comprise any liquid but in a preferred embodiment comprises a defoaming agent, is injected by suitable means such as described in Reese U.S. Pat. 2,639,674 down the hollow region of sucker rod 36-and flows into annular chamber 65 while sucker rod 36 is reciprocatingly driving cylinder 40 that cooperates with tubing 20 and the noted valves to comprise-a pumping means. The liquid then fiows from annular chamber 65 through means 30 into the oil bearing region and in a preferred embodiment where the packing means 70 is used, the liquid is deposited downhole fro'm packing means 70. Thus, according to the operation of the preferred embodiment of this invention a defoaming liquid can be introduced down the hollowsucker rod and further conducted into the oil bearing region to be intimately mixed with the oil flowing into the cased well so as to reduce foaming.

Examples of liquids that can be introduced down hollow sucker rod 36include defoaming agents, slurries, fluid cemerits, water for water flooding, gas for fire flooding. As previously noted in a preferred embodiment, a defoaming agent is introduced. The defoaming agent used in the preferred embodiment can comprise any material capable of being injected in the bore hole according to-this invention that will reduce or eliminate foaming. Specifically, two kinds of silicon compounds are commercially available to reduce or eliminate foam. One is a compounded silicon antifoam and the other is a straight dimethyl oil. Compounded antifoams'are dispersions of silica filler in a low viscosity silicon fluid. The dimethyl silicon oils are high viscosity long chain polymers of silicon to oxygen bonds with two methyl groups attached to each car- This invention is thus broadly applicable to the introduction of a liquid into the oil bearing region of aiwell through a hollow sucker ro'cl. 4

As noted above, the drawing is merely diagrammatic and is not intended to fully show all component parts of the'eq'uipment which one skilled in the art would routinely design 'for operation. Specifically as noted, the position of packing means 70 can vary within the length of the column and several embodiments of means 30 and means 75 are provided. Indeed,

the showing of one element of piece of equipment does not mean that all such are similar pieces of equipment which may or can be designed by one skilled in the art in possession of this-disclosure. cannot be utilized as substitution therefor.

Likewise, the omission of an element which one skilled in the art may include in an actual unit does not mean that such a piece of equipment is intended to be omitted simply because it does not appear in the drawing. Sufiice to say the drawing is for illustrative purposes only, as is the description thereof.

1 claim:

1. Apparatus for introducing a liquid into the oil bearingregion of a producing cased well comprising:

a. a length of tubing residing in said cased well from an uphole location to said oil bearing region;

b. reciprocal pumping means positioned within said casing in the oil bearing region adapted to pump produced fluid up said tubing;

c. a hollow suckerrod containing a passageway from the exterior of the rod to the hollow region, said rod positioned within said tubing and adapted to reciprocally actuate said pumping means;

d. first and second packing means positioned respectively.

up hole and down hole from said sucker rod passageway slidably sealing said sucker rod to said tubing so as to form an annular chamber;

e. means to conduct said introduced liquid from said annular chamber to said oil bearing region; and

f. bypass means to conduct said produced fluid around said annular chamber and up said tubing.

2. The apparatus of claim 1 further comprising:

a. closure means between said casing and tubing; and

b. means to communicate produced gas upward through said closure.

3. The apparatus of claim 2:

a. wherein said closure means is positioned down hole from the inlet of said pumping means;

b. wherein said tubing contains a passageway positioned up hole 'from said closure means and downhole from said.

tube centrally positioned within said first tube.

5. A method of introducing a liquid into the oil bearing zone of a producing cased well comprising the steps of:

a. providing a reciprocally driven pump in pumping position in said oil bearing zone;

b. actuating said pump with a hollow sucker rod containing a passageway from the exterior of the rod to said hollow region;

c. providing a tubular closure around said sucker rod;

d. forming an annular chamber by:

chamber to said'oil bearing region comprises a second I 1 providing a first closure means uphole from said sucker rod passageway slidably sealing said sucker rod to said tubular closure; v

2 providing a second closure means downhole from said sucker rod passageway slidably sealing said sucker rod to said tubular closure;

e. conducting a liquid down said hollow sucker rod through said passageway and annular chamber and into said oil bearing zone;

f. pumping produced fluid from said oil bearing zone around said annular chamber and up said tubular closure to an uphole location; and

g. recovering produced gas from said oil bearing zone.

6. The method of claim 5 further comprising the steps of:

a. providing a closure within said casing;

b. providing a passageway through said casing closure for the recovery of said produced gas.

7. The method of claim 6:

a. wherein said casing closure is positioned downhole from the inlet of said reciprocally driven pump;

b. wherein said liquid comprises a defoaming agent;

c. wherein said tubular closure contains a passageway positioned uphole from said casing closure and downhole from said pump inlet. I

8. The method of claim 7 further comprising:

a. recovering produced gas through a tubular passageway in said casing closure; and v p b. introducing said defoaming agent into said oil bearing zone through a tubular member positioned annularly within said gas recovery passageway.