US2889881A

US2889881A - Oil recovery by in situ combustion

Info

Publication number: US2889881A
Application number: US584453A
Authority: US
Inventors: Joseph C Trantham; Henry O Dixon
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1956-05-14
Filing date: 1956-05-14
Publication date: 1959-06-09
Anticipated expiration: 1976-06-09

Description

on. nncovnnv BY 1N srro COMBUSTION Joseph C. Trantham and Henry 0. Dixon, Bartl esville,

Okla, assignors to Phillips'Petrolenm' Company, a corporation of Delaware No Drawing. Application May 14,1956 Serial No. 584,453

6 Claims. (ill. 166-11) This invention relates we process for the recovery of oil' by in situ combustion particularly from reservoirs containing high gravity crude (low carbon residue) which normally burns without leaving a combustion-supporting residue by direct air injection. 7

The recovery of oil from oil bearing formations by in situ combustion is currently being emphasized as a production technique. The conventional method employed comprises initiating combustion of the oil adjacent a bore hole in the formation by any suitable means and injecting air through the bore hole into the formation so as to drive the combustion zone or front radially and laterally outwardly from the bore hole. A recent development in in situ combustion technique in the fieldof oil r ecoverey is disclosed and claimed in the copending' application of John W. Marx, Serial No. 526,388; filed August 4, 1955, now abandoned, and comprising establishing a combustion zone around a production well by conventional methods so as" to provide a combustion Zone and a heat reservoir of sufficient extent and temperature to permit cutting the direct flow of air through the production well and injecting air into the formation through one or more spaced-apart wells from the production well so as to cause the air tofiow to the com-' bustion zone at the production well and support combustion therein so that the combustion front is advanced countercurrently to the flow of air toward the injection well or wells. This technique is designated finverse air injection in situ combustion as opposed to direct air in-' jection through the well or bore hole around which combustion is initiated.

Another recent development in recovery of oil by in situ combustion'is disclosed in'the copending application of], C. Trantham and A. Rrschleicher, Serial No. 529,- 916, filed August 22,- 1955, and comprises continuing the injection of air through one or more injection wellsafter the combustion front has been'advanced, by inverse air injection, to the injection well or wells so as to reverse the movement of the combustion front and drive the same back through the formation to the production well around which combustion was originally initiated. In this technique, designated thermal echo, the returning combustion front feeds on the residual carbon deposited in the formation during the inverse air injection phase of the process.

It has been found that in many oil-bearing formations the crude is of such high API gravity (and low carbon residue) that the hot gases from a combustion front initiated around an injection Well drive the hydrocarbon materials substantially completely away from the area in front of the combustion front thereby leaving insufficient fuel to sustain combustion and the fire goes out. This renders it impossible to initiate combustion and build up a sufiicient combustion zone and heat reservoir to permit reversing the direction of the flow of air to the combustion zone in order to establish inverse air injection to support and drive the combustion zone toward the Patented .lune 9, 1959 2 surrounding injection wells and away from thewell in which the combustion is originally initiated.

Hence it is an object of the invention to provide a process or method for initiating in situ combustion for sup porting inverse air injection and recovery of oil in an oil reservoir or formation containing crude of high specific gravity. Another object is to provide a method of oil recovery by in situ combustion from an oil bearing formation which is incapable of supporting in situ combustion by direct air injection; Other objects of the invention will become apparent from a consideration of the accompanying disclosure. 7

The method of the invention comprises depositing a heavy hydrocarbon oil, such as heavy crude oil', in the formation surrounding a' production well or bore hole and initiating combustion of the deposited heavy oil by any suitable conventional method so as to burn a sufiicient amount of the oil to establish a combustion zone which contains enough heat to permit cutting off the directinjection of air or other combustion-supporting gas and feeding air to the combustion zone from one or more spaced-apart wells or bore holes through the formation whereby the combustion zone is advanced toward the injection well and combustion products and produced hydrocarbons are driven to the production Well from which they are recovered by conventional means. The heavy oil is injected into the formation through a well or bore at a selected location so as to penetrate thetemperature sufficient to initiate combustion which is in the range of approximately 500 to 700 F.

Burning of the oil in the formation surrounding the bore hole leaves a carbon residue which is sufiiciently hot to support combustion' when the direction of the air is reversed and fed thereto from surrounding injection wells.

The quality of depositedoil burned in the formation mu st be sufiicient' to build up a" reservoir of heat which holds the temperature sutlicie'n'tly high to support combustion when the inverse air reaches the combustion area. It is essential to burn only a portion of the deposited heavy oil so that a reserve is'left to prevent vaporization of all ofthe original oil in thefdrmation directly outside of the deposited oil and to pr'ovide'a continuous bed of fuel from the heat reservoir or combustion zone to the injection wells. The arrival of the inverse air from the surrounding injection wells then revives the combustion zone. After inverse air injection and attendant combustion is established, the remaining heavy oil is burned and, as the inverse air injection is continued, the combustion front is propagated radially outwardly and laterally past the limit of the heavy oil saturation and the burning is continued in the light oil reservoir so as to advance the combustion front to the injection wells. In one embodiment of the invention the injection of air is continued after arrival of the combustion front so as to reverse the direction of its movement and drive it back to the production well, thereby subtantially completely denuding the formation of hydrocarbons.

In order to illustrate the invention a 4 foot long stainless steel tube 2 inches in diameter was filled from one end up to within 2 or 3 inches of the other end with clean dry Wilcox sand (from the Oklahoma City area). The sand was compacted in the tube and Burbank crude of high gravity and low carbon residue was forced through the sand by air pressure applied to an oil reservoir connected with the stainless steel tube by a conduit. After saturation was complete the excess crude was blown off until a negligible amount of the crude was coming off the tube. The remaining short section of the tube was packed with Clear Creek tar sand of low gravity and high carbon residue. The packed tube was set up in horizontal position for an in situ combustion test. An electrical heater was positioned at the tar sand-end of the tube and a slow stream of nitrogen was injected through the heater into the tube during the warm up until the sand adjacent the heater reached about 600 F. at which time the nitrogen was suddenly switched ofi and air was passed through the heater into the tar sand. lgnition of the tar was immediately initiated in the tar sand and after the combustion front moved about half the length of the tar sand section, the direction of air was reversed so that it passed thru the sand soaked with Burbank crude before it reached the combustion area or front and the heater was cut off. The combustion front then advanced by inverse air injection thru the remaining tar sand and then thru the sand saturated with Burbank crude without any indication of discontinuity.

Combustion front temperatures were taken along the tube at regular intervals and it was found that the temperature ranged from 1290 to 1800 F. at space velocities in the range of 350 to 420 standard cubic feet per hour/ft. (By reducing the space veiocity to the order to 250 standard cubic feet per hour/ft. the temperature could probably have been reduced to 1050-ll50 F.)

The test demonstrates the feasibility of initiating and sustaining in situ combustion in an oil sand containing a high gravity and low carbon residue crude by the method of the invention.

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.

We claim:

1. A process for recovering hydrocarbons by in situ combustion from an underground formation containing high A.P.l. gravity crude oil of insufiicient carbon residue to support combustion by direct injection of combustion-supporting gas, comprising depositing in an area of said formation surrounding a production borehole therein a mass of heavy oil capable of depositing substantial combustion-supporting carbon when burned in the formation; burning the deposited oil by direct injection of O -containing gas thru said borehole to heat up the formation containing same and establish a carbon residue of sufficient temperature to support combustion when the injection of said gas is cut off and same is passed thru said formation to the hot coke from a surrounding area; terminating the injection of said gas thru said pro- 4 duction borehole; and injecting said gas thru said formation from a surrounding area so as to contact said hot carbon residue while at combustion-supporting temperature to establish inverse movement of a combustion front in said formation.

2. The process of claim 1 wherein said gas is air and inverse air injection is effected thru a plurality of injection boreholes in said formation spaced apart from said production borehole and combustion products and produced hydrocarbons are recovered from said production borehole.

3. A process for recovering hydrocarbons by in situ combustion from an underground formation containing high A.P.I. gravity crude oil of sufficient carbon residue to support combustion by direct injection of combustion-supporting gas, comprising depositing in an area of said formation thru at least one production borehole therein a mass of heavy oil capable of depositing combustion supporting coke when burned in the formation, said area extending into said formation several feet from said borehole; burning a substantial portion but not all of the deposited oil by air injection thru said production borehole to establish a hot combustion zone in the form of hot carbon residue which function as a heat reservoir sufiicient to maintain combustion supporting temperatures therein while air is being passed thru at least one injec tion borehole spaced apart from said production borehole and thru the formation to said combustion zone; when said heat reservoir is established, cutting off the injection of air thru said production borehole; and then passing air to said combustion zone thru said injection borehole so as to advance said combustion zone countercurrently to the flow of air.

4. The process of claim 3 wherein the injection of air is continued until the combustion zone has reached said at least one injection borehole.

5. The process of claim 4 wherein the injection of air is continued after said combustion zone has reached said at least one injection borehole so as to reverse the direction of said combustion zone and drive same back toward said production well.

6. The process of claim 3 wherein combustion is initiated in a deposited mass of heavy oil adjacent a production borehole around which are positioned several injection boreholes thru which combustion-supporting air air is injected.

References Cited in the file of this patent UNITED STATES PATENTS 1,457,479 Wolcott June 5, 1923 1,978,655 Straight Oct. 30, 1934 2,584,606 Merriam et al. Feb. 5, 1952 2,642,943 Smith June 23, 1953 2,761,512 Bond Sept. 4, 1956 2,793,696 Morse May 28, 1957 Attesting Oflicer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,889,881 June 9, 1959 Joseph C, Trentham at 2.1..

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should readas corrected below.

Column 1, line 29, for "recoverey" read recovery line 31., for "comprising" read comprises line 51, for "cumbustion" read m combustion column 2, line 28, after "bore" insert hole -==-,3 column 4, line 14, for "sufficient" read m insufificient line 212,, for "function" read functions Signed and sealed this 23rd day of February 1960n SEAL) ttest:

KARL H AXLINE. ROBERT C. WATSON Commissioner of Patents

Claims

1. A PROCESS FOR RECOVERING HYDROCARBONS BY IN SITU COMBUSTION FROM AN UNDERGROUND FORMATION CONTAINING HIGH A.P.I. GRAVITY CRUDE OIL OF INSUFFICIENT CARBON RESIDUE TO SUPPORT COMBUSTION BY DIRECT INJECTION OF COMBUSTION-SUPPORTING GAS, COMPRISING DEPOSITING IN AN AREA OF SAID FORMATION SURROUNDING A PRODUCTION BOREHOLE THEREIN A MASS OF HEAVE OIL CAPABLE OF DEPOSITING SUBSTANTIAL COMBUSTION-SUPPORTING CARBON WHEN BURNED IN THE FORMATION; BURNING THE DEPOSITED OIL BY DIRECT INJECTION OF O2-CONTAINING GAS THRU SAID BOREHOLE TO HEAT UP THE FORMATION CONTAINING SAME AND ESTABLISH A CARBON RESIDUE OF SUFFICIENT TEMPERATURE TO SUPPORT COMBUSTION, WHEN THE INJECTION OF SAID GAS IS CUT OFF AND SAME IS PASSED THRU SAID FORMATION TO THE HOT COKE FROM THE SURROUNDING AREA; TERMINATING THE INJECTION OF SAID GAS THRU SAID PRODUCTION BOREHOLE; AND INJECTING SAID GAS THRU SAID FORMATION FROM A SURROUNDING AREA SO AS TO CONTACT SAID HOT CARBON RESIDUE WHILE AT COMBUSTION-SUPPORTING TEMPERATURE TO ESTABLISH INVERSE MOVEMENT OF A COMBUSTION FRONT IN SAID FORMATION.