US 3180411 A
Description (OCR text may contain errors)
April 27, 1965 H. w. PARKER 3,180,411
PROTECTION OF WELL CASING FOR IN SITU COMBUSTION Filed May 18, 1962 2 Sheets-Sheet 1- FIG. 2
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H. W. PARKER BY y A TTORNEVS FIG.
April 27, 1965 H. w. PARKER PROTECTION OF WELL CASING FOR IN SITU COMBUSTION Filed- May 18, 1962 2 Sheets-Sheet 2 INVENTOR. H W PARKER A TTORNEKS lhldddll Patented Apr. 2?, 1%55 3,18%,411 RQT-"QTE@N QB WELL QASlNG FUR 1N SITU CGIvlBUS'llGN Harry W. Parker, Eartlesville, @kla, assignor to Phillips Petroleum (Zompany, a corporation oi Delaware Filed May 18, $62, Ear. No. 195,766 8 Ciaims. (Ql. led-ll) This invention relates to a method and apparatus for protecting well casing and tubing from overheating during in situ combustion.
Frequently a relatively deep oil structure is being produced by conventional methods (such as pumping) and the casing and tubing leading to this structure pass thru other oil bearing strata which are amenable to production by in situ combustion. To illustrate, in North and West Central Texas, the Ellenberger formation lies about 2280-24-00 feet deep while the Strawn sand is about 1600 feet deep and direcdy over the Ellenberger stratum. The Ellenberger stratum is being produced by a number of wells thru casing and tubing extending thru the Strawn sand. It has recently become desirable to produce the Strawn sand by in situ combustion. However, by igniting the Strawn sand around certain wells therein and in jecting combustion gas to the ignited area, the resulting combustion zone is moved thru the sand to other wells therein and contacts the deeper wells extending to the Ellenberger stratum. Since the temperature in the burning stratum reaches levels (IOOO-ZQOG" F.) which melt or otherwise damage the casing and tubing of the deeper Wells, it is essential to protect these wells by some method. Also, in producing hot gases from a combustion zone in an oil bearing stratum, the production well tubing and casing are overheated. This invention is concerned with a method of protecting such wells from damaging tern erature.
Accordingly, it is an object of the invention to provide a process and apparatus for protecting the casing and tubing of a well extending thru a shallow stratum, being produced by in situ combustion, to a deeper producing formation. Another object of the invention is to protect the casin and tubing of wells extending to or thru a burning carbonaceous stratum. 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 comprises providing a cooling zone or chamber just above the lower end of a casing and tubing in a production well adjacent a stratum undergoing in situ combustion, and maintaining suitable vaporizable liquid coolant such as water, in the lower section of said chamber so as to dissipate heat from the casing and tubing. The chamber may extend all of the way to the well head so that adequate condensation space is provided in the cool annulus nearer the well head.
Another aspect of the invention comprises providing a cooling zone or chamber around a well casing extending through an upper stratum, being produced by in situ combustion, to a lower producing stratum and maintaining a suitable liquid coolant in the cooling zone which dissipates the heat of combustion of the carbonaceous material adjacent said casing. In one aspect of the invention, the tubing-casing annulus is packed oif below the upper stratum and the annulus above the packer is filled with the liquid coolant to a level at least as high as the top of the adjacent stratum. In another aspect of the invention, a larger casing is extended from ground level through the upper stratum (to be burned) and a smaller diameter casing is set from a level substantially above the upper stratum extendin to the lower producing stratum, thereby providing an annulus between the lower section of the upper casing and the upper section of the lower casing which is sealed off, with the coolant therein,
fter removing the air. This section of the two casings is preferably fabricated above ground with a coolant sealed therein and the same is then set at the proper level in the well so that the coolant extends from a level below the upper stratum to a level above same.
A more complete understanding of the invention may be had by reference to the accompanying schematic drawing of which FIGURE 1 is an elevation in partial section of an arrangement of wells in accordance with the invention; FIGURE 2 is a fragmentary elevation in cross section iHustrating a second embodiment of the invention; PlGURE 3 is an elevation in partial section of a production well arrangement using the invention; and FIGURE 4 is a fragmentary elevation in partial cross section showing a second embodiment of the device of FIGURE 3.
Referring to FIGURE 1, an upper stratum 10 is penetrated by wells 12 and l4- and a lower producing stratum 16 is penetrated by well l8. Well 18 is provided with casing 29 extending through stratum 1t) and with tubing 2.2. A packer 24 is set between tubing 22 and casing 20 just below stratum 10 and a suitable liquid coolant 26 is positioned in the annular cooling chamber above packer 24 so that the liquid extends at least to the upper level of stratum 1-9.
Well 12 is provided with casing 28 and tubing 39 extending to a level adjacent stratum 19. Well 14 is provided with similar casing 32 and tubing 34. A pump 36 is positioned on the lower end of tubing 22 in well 18.
In operation, it is conventional to ignite stratum 19 around well 12 by any suitable means, such as burning a charcoal pack in well 12 Within stratum l0, and injecting a combustion supporting gas, preferably, containing a small concentration of fuel gas (1-3 or 4% by volume) through well 14 (as through tubing 34) so as to force the combustion supporting gas throughthe stratum to the ignited area around well 12 and cause the combustion zone to move through stratum ill to well 14. In passing well 18, the combustion zone heats casing 26 and the coolant 26 in the annular cooling zone adjacent stratum 19 is heated and boiled so that the heat of vaporization dissipates the heat imparted to the casing by the combustion and keeps the casing below a deleterious temperature. The vaporized coolant is cooled on the side of casing 20 above stratum it which results in condensation and refluxing.
Liquids which function as desirable coolants include mercury, sulfur, stable organic compounds such as polyphenyls, water, kerosene, high boiling point alcohols such as ethylene glycol, etc. Polyphenyls are preferred because they are cheap and stable at temperatures up to 800 to 900 F. Any coolants known to the art may be utilized in the cooling zone. The invention is not dependent upon the use of any particular coolant.
Referring to FIGURE 2, a prefabricated section of easing ll comprises a large diameter casing 42 extending to a level below stratum it) and a smaller casing 44 of smaller diameter, extending to a level substantially above stratum 1b to provide ample condensing space 4-6 above liquid coolant '43 in the resulting annulus between the two casings. Cooling chamber 59 is sealed gas tight by annular plate 52 welded onto the bottom of casing 42 and onto casing 44, and by plate 54 welded onto the top of easing d4- and to casing 42. It is to be understood that casing 42 extends to the Well head and casing 44 extends to the proximity of the lower producing zone.
When casing section as is fabricated above ground, coolant 48 is positioned therein and the condensation space as is preferably evacuated before sealing the cooling chamber. This facilitates the cooling process in which coolant 43 is boiled and condensed in the upper section 45 of the cooling chamber. When utilizing organic compounds as cooling liquids, it is desirable to fill ers may be set in lieu of annular plates 52 and 54 to seal oil the cooling chamber. Before setting the upper packer, the coolant is positioned in the cooling chamber 50.
Referring to FIGURE 3, a stratum 60 is penetrated by a well 62 provided with casing 64 and tubing 66 extend- ,ing to a-level adjacent stratum 60. An annular combustion zone 68 surrounds Well 62 and hot combustion gases are being driven into the well below the tubing. A packer 70 seals off the tubing-casing annulus adjacent'the lower end of the tubing, providing a cooling chamber 72, extending to the well head. Liquid coolant 74 fills the lower section of chamber 72 to level 76. The section of chamber 72 above level 76, designated 78, comprises a condensation Zone or section.
:Boiling liquid dissipates heat from the gases passing thru the'tubing to the well head by indirect heat exchange 3. The structure of claim lrwherein said chamber is formed bya first larger diameter casing in said well extending to a level just below the bottom of said second stratum; a second casing of smaller diameter extending firoma level substantially above said second stratum to a level substantially below said first casing; and closure means in the resulting annulus between the overlapping casings at levels above and'below said second stratum seated against the casings and sealing said chamber, said coolant occupying only about the lower half of said chamber but at least to the top ofsaid second stratum.
4. The structure of claim 3 wherein said chamber is at 'least partially evacuated. I
therewith thru tubing 66 to prevent damage to the tubing and easing. V
In FIGURE 4, production well 80 penetrates oil stratum 82 undergoing production by in situ combustion. Well 80 is provided with casing 84 and tubing 86, terminating just above the stratum. Cooling chamber 88 is formed by a cylindrical section of conduit 90 sealed to the lower end of tubing 86 by annular plate 92 and by packer 94 at its upper end. Asbestos 'or refractory concrete packing 96 packs off the lower end of annulus 98 to prevent condensation of oil in this annulus.
Positioning packer 9.4 in the mannershown in FIG- URE 4 allows use of a packer with non-metallic seals.
The remoteness from the hot gases entering the Well below plate 92 and the presence of coolant adjacent the .packer protects the packer from excessive heat and eliminates the problem of positioning seats in the casing and the tubing required for metal seals.
Certain modifications of the invention will become ap parent to those skilled in the art and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.
I claim: I
1. In an earth structure wherein a first oil-bearing stratum lies substantially below a second oil-bearing stratum and is penetrated by a well including casing and .tubing passing thru said second stratum, and said second stratum is being produced by in situ combustion so that .a' combustion zone at a temperature in the range of 1000 to 2000 F. is moved thru said second stratum adjacent said casing and tubing, said secondstratum being at said temperature: a structure for protecting said castically from just below the bottom of said second stratum 5. The structure of claim 3 wherein hydrogen occupies space in said chamber above said coolant and said coolant comprises an organic compound.
6. In an earth structure wherein an oil-bearing stratum is being produced by in situ combustion comprising igniting said stratum and injecting O -containing gas into the ignited area from an injection 'well and producing hot hydrocarbons and combustion gases thru a production well therein thru tubing and easing extending to a level adjacent said stratum, whereby said hot gases heat said stratum adjacent said casing to a temperature in the range of 1000 to.2000 F. and overheat and damage said casing and tubing; a' structure comprising closure means sealing 05 the tubing-casing annulus at said level forming an elongated upright annular chamber, said closure means comprising a cylindrical section smaller in diame .ter than said casing extending upwardly from the lower end of saidtubing. and sealed therewith at its lower end .and a sealing means between said casing and said section adjacent its. upper end, whereby last said sealing means is substantially above the bottom of said chamber; and a vaporizable liquid coolant in a lower section of said chamber providing a vertically elongated condensation section in the upper section of said chamber.
7. The structure of claim 6 including packing means inthe annulus between said casing and said section at its lower end 'to exclude oil vapors from last said annulus.
, 8. A process for producing oil from a second oil-bearing stratum overlying a deeper first oil-bearing stratum to'which a first well having a casing and tubing string extends, Said first well passing thru, said second stratum, which comprises igniting said second stratum around a second well therein; feeding air to the ignited area thru at least one well in said second stratum so as to move a combustion zone therethru at a temperature in the range ,Of 1000 to 2000 F. adjacent said first well, and recover- ;maintaining a'liquid coolant in the annulus of said first to substantially above the top thereof, said casing forming a the outermost wall'of said chamber; and a vaporizable liquid coolant insaid chamber extending from the bottom thereof only to a level just above the top of said secondmstratum thereby forming a vertically extended vapor zone in said chamber above'said liquid.
' 2. The structure of claim 1 wherein saidchamber is formed by setting apacker' around said tubing adjacent the bottom of said second stratum to seal off the casingtubing annulus. a
Well extending from just below to just above said second stratum, and providing a vertically extended vaporizing zone for .saidvcoolant in saidannulus above saidcoolant for cooling and refluxingsaid coolant.
References Cited bythe Examiner UNITED STATES PATENTS 1,413,197' 4/22 Swan 16657 2,346,060 4/44 Yeatman 166-89 2,530,280 11/50 'Ackley l66-39 12,649,915 8/53 Miller 166-224 3,013,609 12/61 Brink -Q. 166-39 BENJAMIN 'HERSH, Priniary Examiner.