|Publication number||US3386507 A|
|Publication date||Jun 4, 1968|
|Filing date||Oct 3, 1966|
|Priority date||Oct 3, 1966|
|Publication number||US 3386507 A, US 3386507A, US-A-3386507, US3386507 A, US3386507A|
|Inventors||Lumpkin William B|
|Original Assignee||Phillips Petroleum Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (9), Referenced by (7), Classifications (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
June 4, 1968' w. a. LUMPKIN OIL WELL PERFORMANCE Filed Oct. 5. 1966 JJw ZOFUMWZ.
ZOFUDQOWE INVENTOR W. B. LUMPKIN BY 3 i ATTORNEYS United States Patent 3,386,507 OIL WELL PERFORMANCE William B. Lumpkin, Caracas, Venezuela, assignor to Phillips Petroleum Company, a corporation of Delaware Filed Oct. 3, 1966, Ser. No. 583,625 5 Claims. (Cl. 16611) This invention relates to a process for opening up a stratum around an oil-producing well to improve production thru the well.
Recovery of oil from producing formations is accompanied by numerous operating problems, particularly around the production Wells into which the oil is driven. Flow of oil into the production well is frequently impeded near the production well by emulsion blocks, solidto-semisolid asphaltic and paraffinic materials deposited from the oil passing thru the stratum into the production well, etc. Achievement of an approach to total recovery of available oil is difficult because of varying reservoir conditions and methods of production resulting in bypass of areas, partial sweep recovery, etc. In fact, in certain fields which produce heavy grades of crude oil, the recovery by primary methods amounts to only about 5 percent of the in-place oil.
One approach to the problem of improving oil production thru a production well comprises applying heat at high temperature to the stratum immediately surrounding the production well to increase permeability and porosity of the surroundin annulus. Whether achieved by in situ combustion, downhole heaters, or other means, this method increases permeability and porosity around the wellbore, reduces or eliminates asphaltic and paraflinic deposits and emulsion or water blocks, and, where the formation is amenable to fracturing, fractures are-produced to increase flow of oil. However, direct application of heat to the stratum surrounding the production well tends to move the oil away from the well.
This invention is concerned with a method or process for opening up a stratum around a production well to improve production while avoiding the driving of oil away from the production well.
Accordingly, it is an object of the invention to provide a process for improving the flow rate of oil thru a stratum into a production well. Another object is to increase the permeability of an oil stratum in an annulus immediately surrounding a production well to increase the flow of oil into the well when production is resumed. A further object of the invention is to open up a stratum immediately surrounding a production well while avoiding the driving of oil away from the well. Other objects of the invention will become apparent to one skilled in the art upon consideration of the accompanying disclosure.
A broad aspect of the invention, as applied to an oil stratum penetrated by an injection well and a production well, comprises opening up the stratum to the flow of gas from the injection well to the production well as by injecting air intothhe production well until it is produced thru the production well; thereafter igniting combustible material in the stratum adjacent the production well to establish a combustion zone; feeding air to the combustion zone by injecting same thru the injection well to cause the combustion zone to move into the stratum from the production well in a reverse-burning operation, depositing coke in the stratum traversed by said zone; after the combustion zone has been moved into the stratum a substantial distance, such as at least 2 feet but not more than about of the distance between wells, substantially reducing the air flow rate to the combustion zone so as to terminate reverse movement thereof; and, after advance of the combustion zone has been terminated by insufficient air supply, again injecting air at a sufiicient rate into the injection well to cause the combustion zone to move back toward the production well and burn the coke deposited during the reverse-burning phase of the process. The reverse movement of a combustion zone in a carbonaceous stratum requires an air flow rate of at least 20 standard cubic feet per hour of air per square foot (s.c.f./hr./ft. of cross section of stratum. Reducing the flow rate of air substantially below this value terminates the advance of the combustion zone toward the injection well and again increasing the flow of air has the effect of driving the combustion zone back to the production well. During the reverse movement of the combustion zone, coke is laid down in the stratum thru which the combustion zone passes and during the direct drive of the combustion zone back to the production well, this coke is consumed so as to substantially completely burn out all of the carbonaceous material in the stratum thru which the direct drive combustion zone passes. This cleans out the rock or sand so completely that it is found to be white and free of carbonaceous material.
In order to reverse the reverse-burning combustion zone, the flow of air can either be substantially reduced to below 20 s.c.f./hr./ft. or it can be terminated for a substantial period of time, such as several hours to several days, so that upon resumption of the injection of air at a substantial rate, the combustion zone is driven back to the production well. Merely reducing the air flux to less than 20 s.c.f./hr./ft. causes reversal of the combustion zone to a direct drive back to the production well.
Following the opening up of the stratum around the production well by the reverse-burning and direct-drive combustion zone technique, production of oil from the stratum into the production well is resumed with any suitable production technique, including water drive, steam drive, or any miscible fluid drive operable in the particular oil stratum involved.
The combustion zone in the stratum adjacent the pro duction well is established by any suitable method. One method comprises burning a charcoal pack in the production well to heat the adjacent formation to a combustion-supporting temperature and feeding air into the hot formation from the injection well. In this technique, about 24 weight percent of natural gas or other suitable fuel gas may be injected in the air to facilitate the establishment of the combustion zone.
A preferred method of establishing the combustion zone comprises injecting an autoignitable fuel into an annulus of the stratum adjacent the production well after establishing air permeability and causing the ignition of the autoignitable fuel by injecting air thru the injection well and forcing same into the annulus impregnated with the autoignitable fuel. The copending application of F. A. Klein and M. R. Dean, Ser. No. 559,804, filed June 23, 1966, discloses such a method of igniting a stratum around a well and autoignitable fuel compositions used in such a process. Autoignitable liquid fuels include lung oil, linseed oil, tall oil, red oil, castor oil, oleic acid, linseed oil fatty acids, tall oil fatty acids, and turpentine. The autoignitable fuel may be mixed with a liquid hydrocarbon ranging from gasoline to crude oil and may contain a minor concentration of an oil-soluble oxidation catalyst such as cobalt naphthenate to enhance the oxidation of the fuel mixture.
A more complete understanding of the invention may be had by reference to the accompanying schematic drawing which is an elevation thru an oil stratum penetrated by injection and production wells.
Referring to the drawing, an oil stratum 10 is penetrated by a production well 12 and an injection well 14. Production well 12 is provided with a tubing string 16 and injection well 14 is provided with a tubing String 18. At the stage of the process illustrated, a fire front or combustion zone has been advanced from production well 12 outwardly from the well into the stratum the desired distance and this is followed by the direct drive of the combustion zone 20 back to the production well. It is to be understood that injection well 14 is either one of a ring of injection wells around well 12 or one well in a line of wells parallel with a line of production wells 12, there being another line of injection wells (not shown) on the opposite side of the line of production wells 12.
Assuming that oil has been produced by fluid drive from injection well 14- to production well 12 until the rate of flow of oil into well 12 has substantially decreased due to accumulation of plugging material in the annulus immediately surrounding well 12, the production process is terminated and air is injected thru tubing string 18 into injection well 14 until air is being produced thru well 12. At this time, ignition of the carbonaceous material in the annulus surrounding Well 12 is effected by any suitable means, such as those previously described. It is preferred to inject an autoignitable liquid fuel composition into the annulus immediately surrounding well 12 and resume air injection thru well 14 so that the flow of air into the annulus impregnated with the autoignitable fuel causes ignition thereof and, also, ignition of the in-place oil. Continued injection of air thru well 14 then advances the resulting combustion zone toward well 14 and away from well 12, as illustrated at 20. During the reverse movement of combustion zone 20 away from well 12, coke is laid down in the stratum thru which the combustion zone passes. After the combustion zone has been advanced to the desired location away from well 12, air injection is reduced or terminated for a substantial period and then resumed so as to re-establish combustion and drive the combustion zone back to the production well, cleaning out the sand or rock in the annulus thru which the combustion zone has moved and opening up the stratum to more rapid production of oil. Thereafter, the fluid drive process from injection well 14 to production well 12 is resumed.
In the event the cleaned-out annulus later becomes impregnated with solid-to-semisolid carbonaceous material, the same is cleaned out by again causing a combustion zone to move out from well 12 into the stratum and back again in the manner described herein.
Certain modifications of the invention will become apparent to those skilled in the art and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.
1. In a process for producing oil by fluid drive thru an oil stratum penetrated by an injection well and a pro- 4 duction well wherein a driving fluid is injected into said stratum to drive oil into said production well and flow into said production well is impeded by combustible material occupying the pores of said stratum, the method of improving flow of said oil which comprises to steps of:
(a) injecting air into said injection well until air is being produced thru said production well;
(b) initiating combustion of carbonaceous material in said stratum adjacent said production well to establish a combustion zone;
(c) injecting air as in step (a) to feed the combustion zone of step (b), cause same to move away from said production well, and leave a coke deposit in the area traversed by said combustion zone;
(d) continuing step (c) until said zone has moved away from said production well a distance of at least 2 feet but not more than about of the distance between said wells;
(e) following step (d), substantially reducing the air flow rate to said combustion zone for a period to terminate movement of said zone away from said production well;
(f) thereafter, again injecting air at a sufiicient rate to drive said combustion zone back to said production well and burn out the coke deposit of step (c); and
(g) resuming the production of oil by fluid drive from said injection well to said production well.
2. The process of claim 1 wherein said fluid drive is a steam drive.
3. The process of claim 1 wherein said fluid drive is a water drive.
4. The process of claim 1 wherein said fluid drive is a miscible fluid drive.
5. The process of claim 1 wherein the combustion zone in step (b) is established by injecting an autoignitable fuel into an annulus of said stratum adjacent said production well and resuming air injection thru said injection well to contact said fuel with said air and cause ignition.
References Cited UNITED STATES PATENTS 2,994,374 8/1961 Crawford et al 16611 2,994,376 8/1961 Crawford et a1 16611 3,032,103 5/1962 Parker 1661l 3,057,403 10/1962 Wyllie 166-2 3,062,282 11/ 1962 Schleicher 166-11 3,064,728 11/1962 Gould 1662 3,126,955 3/1964 Trantham et al 1661l 3,165,154 1/1965 Santourian 166-l1 3,172,467 3/1965 Trantham et a1 1661l X STEPHEN I. NOVOSAD, Primary Examiner.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2994374 *||Oct 28, 1957||Aug 1, 1961||In situ combustion process|
|US2994376 *||Dec 27, 1957||Aug 1, 1961||Phillips Petroleum Co||In situ combustion process|
|US3032103 *||Aug 11, 1958||May 1, 1962||Phillips Petroleum Co||Increasing fluid flow thru an injection borehole|
|US3057403 *||Oct 17, 1958||Oct 9, 1962||Gulf Research Development Co||In-situ combustion process for the recovery of oil|
|US3062282 *||Jan 24, 1958||Nov 6, 1962||Phillips Petroleum Co||Initiation of in situ combustion in a carbonaceous stratum|
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|Citing Patent||Filing date||Publication date||Applicant||Title|
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|International Classification||E21B43/16, E21B43/18, E21B43/243|
|Cooperative Classification||E21B43/243, E21B43/18|
|European Classification||E21B43/243, E21B43/18|