CA1170169A

CA1170169A - Method of treating a well bore

Info

Publication number: CA1170169A
Application number: CA000391866A
Authority: CA
Inventors: Howard I. Lorenz
Original assignee: Pool Co
Current assignee: Pool Co
Priority date: 1981-04-02
Filing date: 1981-12-09
Publication date: 1984-07-03

Abstract

Abstract of the Disclosure Steam is injected into the tubing positioned in a casing in a well bore to conduct heat to a formation in the well bore. Foam is injected into the casing annulus sur-rounding the tubing to assist in retaining heat in the steam that is injected into the tubing, and thereafter slugs of steam and foam are alternately injected into the tubing and circulated down the well bore and then upwardly out of the well bore through the casing annulus to assist in the flow of viscous hydrocarbons from the well bore formation as well as cleaning the well bore and formation.

Description

Summary of the Invention Various well treating procedures employing steam and foam have been employed in the past as re~resented by U. S. Patent Nos. 3,410,344; 3,412,793; 3,463,231; 3,530,939;
3,565,177; 3,583,483; 3,583,489; 3,707,193 and 4,161,217.
The primary object of the present invention is to provide a method of treatiiug a well bore by circulating steam through the tubing in the well bore to a hydrocarbon bearing formation while maintaining foam in the annulus surrounding the tubing to assist in retaining as much heat as possible in the steam until it is discharged from the tubing into the well bore adjacent the formation. The pressure on the foam on the annulus may be maintained as steam and is injected downwardly through the tubing and adjacent the formation un-til the formation has been steam treated a sufficient or de-sired length of ti~ne. Thereafter, slugs of foam and steam are alternately fed into the tubing and circulated downwardly to be discharged out the lower end thereof and circulated up-wardly in the annulus to assist in heating and cleaning of the hydrocarbon bearing formation, as well as increasing the fluidity of viscous hydrocarbons in the formation.
In another method of the invention, the hydrocarbon bearing formation of the well bore may be treated by subject-ing it to alternate slugs of foam and steam to assist in heating and cleaning the formation and well bore as well as increasing the fluidity of viscous hydrocarbons therein.
Brief Description of the Drawings:
Fig. 1 is a schematic view of a cased well bore with tubing illustrating a method of foam packing the annulus .~

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and supplying steam heat to a hydrocarbon formation and sub-sequent flow to clean the well bore and formation.
Fig. 2 illustrates schematically a method of alter-nately slugging the well bore and formation with steam and foam for cleaning thereof and to assist in flow.
Description of the Preferred Embodime In the drawings the well bore is referred to gener-ally by the numeral 10 and is illustrated as having a hydro-carbon bearing formation 11 adjacent the lower portion of the well bore. The well bore 10 is provided with a casing C and a tubing T is provided in the casing C with an annulus A be-tween the casing C and tubing T.
In Fig. 1 a steam generator 15 is connected to the tubing T by the conduit 16 with a valve 18 therein and a pressure gauge 1~. A foam source 20 is communicated by con-duit 21 to the annulus A of the casing C, as shown in Fig.
1, and is provided with a valve 22 in such conduit to control flow between the foam source and the annulus A. A pressure gauge 23 is provided in the conduit 21. A second conduit 25 connects the foam source 20 directly with the tubing T, as shown in Fig. 1, for supplying foam to the tubing T as will be described.
In one procedure of the present invention, hot steam from the steam generator 15 is conducted through the steam line 16 to the tubing T to be discharged from the lower end 30 of the tubing adjacent the hydrocarbon bearing forma-tion 11. As the hot steam is discharged at 30, foam from the foam source 20 is supplied through the foam line 21 to the casing annulus A to fill or pack the casing annulus A

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surrounding the tubing T with foam ~s illustrated at 32. In this procedure, it is contemplated that steam from the generator 15 will be supplied continuously through the steam line 16 to the tubing T and some of the heat from the steam will initially be lost in heating the tubing T.
Foam does not conduct or transmit heat very well and by packing the annulus A surrounding the tubing T with foam, heat loss from the tubing may be retarded. After the initial heating of the tubing T, the heated steam will then heat the hydrocarbon producing formation 11 and transmit heat to the hydrocarbon formation 11 to assist in increasing hydrocarbon flow from the formation as well as to assist in increasing the fluidity of viscous hydrocarbons in such for-mation. Steam may be injected through the tubing T while the annulus A is packed with foam for any suitable length of time. The pressure gauges 23 and 19 may be employed in an endeavor to stabilize or balance the foam column against the pressure of the steam at the lower end 30 of the tubing T in the well bore 10 adjacent the hydrocarbon producing formation 11. This procedure may accomplish the desired treatment of the formation 11. If it does, then valve 22 in conduit 21 is closed and foam along with steam from source 15 may be simul-taneously applied through tubing T to be discharged out the lower end 30 thereof. The foam will assist in carrying par-ticles of viscous hydrocarbon or asphaltic particles up the annulus A and the hydrocarbon, steam and foam will be dis-charged through f:Low line F and conducted to a separator.
In some instances, it will be preferred to pack the annulus A with foam and steam treat the formation 11 as previously described, and then treat the formation and well bore in the hereinafter described manner.

'`7 0 1 6 ~3 After the heatiny by ~he tlot steam of the well bore formation 11 has been completed, while the annulus A is foam packed as described above, the valve 27 is opened and valve 22 is closed. The valve 27 in conduit 25 controls communica tion between the foam source 20 and the tubing T. During this phase of the well bore treatmemt, foam from the foam source 20 is supplied through the foam line 25 and valve 27 to the tubing T so as to provide a slug of foam as repre-sented at 40 in E`ig. 2 therein of any desired length~ The slug 40 of foam is pushed down the tubing T by a slug of steam represented at 41 from steam generator 15, and then an-other slug of foam froin foam source 2~ is supplied to the tubing T followed immediately by a slug of steam 41 supplied to the tubing T continuously as illustrated in Fig. 2. Thus, alternate slugs of steam 41 and foam 40 are supplied to the tubing T to be discharged at the lower end thereof.
The valves 18 and 22 are alternately opened and closed to provide the slugs of steam and foam to tubing T, which flow downwardly and then pass upwardly in the annulus ~
to be discharged through the valve 28 in the flow line F to a separator as previously described. This procedure may be conducted over any suitable desired length of time to accom-plish the heating and cleaning of the formation 11; to clean the formation and well bore and also to assist in increasing the fluidity of viscous hyudrocarbons in the formation 11.
The alternate slugs of steam 41 assist in maintaining the heat in the forma~ion 11 while the alternate slugs of foam 40 act as a carrier medium for entraining particles therein and carrying them up the annulus A as the slugs of steam and foam 01~

are moved in such annulus ~ to be di~charged through the flow line F.
In so~le instances, it is desired only to carry out the latter part of the procedure wherein alternate slugs of foam from the source 20 are conducted to the tubing T, with the slugs of foam being separated by slugs of steam from the steam generator 15. The flow from the foam source 20 and the steam generator 15 may be regulated and controlled by the valves 18 and 27, This portion of tne procedure may be COII-tinued until the desired cleaning and heating of the forma-tion 11 has been attained.

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Claims

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:
i. A method of treating a well bore having a tubing in a casing to facilitate heating and cleaning of a formation in the well bore as well as increasing the fluidity of viscous hydrocarbons comprising the steps of:
a. injecting steam into the tubing to conduct heat to the well bore formation;
b. simultaneously injecting foam into casing annu-lus surrounding the tubing to assist in retaining heat in the steam injected in the tubing; and c. thereafter, alternatively injecting slugs of foam and steam into the tubing and circulating the foam and steam down into and out of the well bore to assist in the flow of viscous hydrocarbons from the well bore formation.
2. A method of treating a well bore having a tubing in a casing to facilitate heating and cleaning of a formation in the well bore as well as increasing the fluidity of viscous hydrocarbons comprising the steps of:
a. injecting a slug of steam into the tubing;
b. injecting a slug of foam into the tubing; and c. continuing to alternately inject slugs of steam and foam into the tubing and circulating the foam and steam down into and out of the well bore to assist in the flow of viscous hydrocarbons from the well bore formation.