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Publication numberUS2754098 A
Publication typeGrant
Publication dateJul 10, 1956
Filing dateJan 21, 1953
Priority dateJan 21, 1953
Publication numberUS 2754098 A, US 2754098A, US-A-2754098, US2754098 A, US2754098A
InventorsHeinze Robert V
Original AssigneeSubmerged Comb Company Of Amer
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for mining sulfur and other substances capable of being modified by heat
US 2754098 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

July 10, 1956 R. v. HEINZE 2 754,098

METHOD AND APPARATUS FOR MI NING SULFUR AND OTHER SUBSTANCES CAPABLE OF BEING MODIFIED BY HEAT Filed Jan. 21, 1953 3 Sheets-Sheet 1 GAS RELEASE AND/6R m LET AS MAY as oesmeo V SULFU? PIT STORAGE) URFACE (Srre FIND SALT Dorks I INVENTOR. ROBERT V HEINZE BY a/ 4 (2.4, pfw

ATT'YS July 10, 1956 25 754,098

R. v. HEI METHOD AND APPARATUS FOR MINING SULFUR AND OTHER SUBSTANCES CAPABLE OF BEING MODIFIED BY HEAT Filed Jan. 21, 1953 3 Sheets-Sheet 2 GAS a SULFUR LEVEL GAS a OIL Fl 6 4 cAsan o GAS 8 OTHER LIQUID M'TL. I

EARTH SURFACE ORE BODY BEARIN;

SULFUR, SALT, PETROLEUM OR OTHER MODIFIABLE MATERIAL INVENTOR. ROBERT V HEINZE y 1956 R. v. HEINZE 2,754,098

METHOD AND APPARATUS FOR MINING SULFUR AND OTHER SUBSTANCES CAPABLE OF BEING MODIFIED BY HEAT Filed Jan. 21, 1953 3 Sheets-Sheet 5 INVENTOR: ROBERT V. HEINZE ATT'YS METHOD AND APPARATUS FOR MINING SULFUR AND OTHER SUBSTANCES CAPABLE OF BEING MODIFIED BY HEAT Robert V. Heinze, Whiting, Ind., assignor to Submerged Combustion Company of America, Inc., Hammond, Ind, a corporation of Indiana Application January 21, 1953, Serial No. 332,471

9 Claims. (Cl. 2623) This invention relates to a new and improved process and apparatus for mining and more particularly to a new and improved method and The usual method by which sulfur is mined is to force hot water (328 F. i) into a conduit which is positioned in the sulfur bearing ore body. The conduit is provided with perforations in its side walls adjacent the end which is in the sulfur bearing ore body. A baffle is provided between these perforations and other perforations farther down in the side wall of the conduit so that the hot water flows into the sulfur bearing ore body where the heatin the water is transferred to the sulfur which then becomes molten. Because it is heavier than the water, the molten sulfur gravitates downwardly and flows into the perforations in the conduit below the bafile. The molten sulfur in the lower end of the conduit is conducted to the surface by means of another conduit disposed centrally within the first conduit. A third conduit containing compressed air is disposed centrally in the second conduit and the column of molten sulfur inside the second conduit is lifted to the surface by means of the compressed air.

This process is difiicult and costly because the hot water is heated in conventional type boilers. That is to say, the water is heated by the transfer of the heat. of combustion through metallic walls. Furthermore, the air is separately compressed and then released without having rendered any other function than that of lifting the molten sulfur from subsurface regions to the surface Where it is handled for further disposition. One factor in the high cost is that fresh, carefully treated water is essential in conventional type boilers. Additionally, even with fresh water the water deposits scale on the metal surfaces which must be cleaned at frequent intervals in order to facilitate heat transfer through the metallic walls of the boiler.

One of the objects of the present invention is to provide a new and improved method for mining sulfur in which gaseous products of combustion used to heat the water are employed in lifting the molten sulfur from the subsurface regions to the surface Where it is handled for further disposition.

An additional object of the invention is to provide a new and improved method for mining sulfur wherein the water which is used to melt the sulfur is heated by direct combustion beneath the liquid level and the gaseous products of combustion together with the heated water are both used in the sulfur mining operation.

A further object of the invention is to provide a method of mining sulfur which does not require the use of fresh water.

Another object of the invention is to provide a method of mining sulfur in which the water used tochange the sulfur to a molten state does not have to be specially prepared and treated before it is heated.

Another object of the invention is to provide a method of mining sulfur in which hot water is used to heat sulfur between 325 F. and 340 F. which in turn is conducted to the subsurface ore body for melting sulfur to be brought to the surface similar to the way it is broughtto apparatus for mining sulfur;

the surface when melted by water. This hot sulfur can be pumped readily to the subsurface ore body. Thus, a minimum quantity of combustion gas and/or air are required for lifting the sulfur to the surface.

A still further object of the invention is to provide a method of mining sulfur in which no boiler tubes are required.

A further object of the invention is to provide a method of mining sulfur .in which there is a material savings in fuel costs.

Another object of the invention is to provide a method a mining sulfur in which the cost of the equipment required is much less than is now the case with the equipment customarily employed.

Another object of the invention is to provide a new and improved apparatus for the mining of sulfur.

An additional object of the invention is to provide an apparatus for the mining of sulfur which is relatively small and compact and is more easily moved from one location to another than is the case with the apparatus customarily used.

A still further object of the invention is to provide an apparatus for mining sulfur which can be used in small units for the working of smaller deposits.

A broader object of the invention is to provide a method and apparatus for the subsurface mining of substances which can be liquefied by heat or the viscosity of which can be reduced by heat or the solubility of which can be increased by heat including but without limitation to not only sulfur but lead, mercury, petroleum oils, shale oils, sodium chloride, potassium chloride, and other solids or liquids normally found beneath the earths surface which are capable of modification or dissolution by heated liquids that are inert thereto or unreactive therewith.

Other objects and advantages of the invention will be apparent from the following description in conjunction with the accompanying drawings, in Which:

Fig. 1 represents somewhat diagrammatically and partly in section with parts broken away one embodiment of the method and apparatus of the present invention;

Fig. 2 illustrates a modified form of one portion of the apparatus shown in Fig. 1;

Fig. 3 represents another modification of a portion of the apparatus shown in Fig. 1;

Fig. 4 represents another embodiment of the invention; and

Fig. 5 illustrates an additional embodiment of the invention.

Generally speaking, the invention provides a method by which liquid is heated and the gaseous products of combustion of the fuel used in heating the liquid together with the resultant heated liquid are passed into a passageway which is in communication with a subsurface area containing a substance which is capable of being melted or dissolved by the heated liquid and said substance is removed through a second passageway adjacent the first passageway, the removal being facilitated by said gaseous products of combustion.

The heating of the liquid which is employed in mining the subsurface material is preferably effected by means of combustion of a fuel beneath the surface of the liquid. The heated liquid together with the products of combustion which are released directly in the liquid are then conducted under pressure to a closed vessel herein referred to as a surge drum where some of the gaseous products of combustion may be released if necessary or desirable. The surge drum provides a means for smoothing the pulsations caused by heating the liquid and evaporation of the liquid. The heated liquid together with a part or all of the gaseous products of combustion are then passed into a passageway in communication with the subsurface material which it is desired to mine or recover. A second passageway in communication with the subsurface material is preferably provided in order to remove the subsurface material after it has been melted, thinned or dissolved as the case may be. Thus. it is possible in a continuous operation to. modify the subsurface material and to recover it continuously. If the operation is carried out intermittently the subsurface material may be modified by the heated liquidand withdrawn at intervals through the smne passageway where the heated liquid is introduced, but this type of operation does not ordinarily lend itself to the most economical recovery of the desired material.

In Fig. l the invention is illustrated with reference to the miningv of sulfur. Heat is generated by means of the submerged combustion burner 1 and raises the temperature of the water 2 which: is forced into the heat exchange chamber 3 through the inlet 4. The hot water and the hot gases of combustion are conducted under pressure through the conduit. 5 to the. surge drum 6. The surge drum 6 provides a means for dampening the pulsations caused. by the heat and steam generation. A conduit 7 provides a-rneans for. releasing gases if necessary or for introducing compressed air or gases in order to increase the gas pressure employed for lifting molten sulfur from subsurface regions to the surface of the ground. The hot gases and hot water are conducted under pressure from. the surge drum 6 through conduit 8 to the pipe or casing 9- which is sunk into the sulfur bearingv layer 10. The lower end of the pipe or casing 9 in the sulfur bearing layer is provided with perforations 11 in the side walls of the casing. These perforations or openings permit the hot water to flow into the sulfur bearing ore and melt the sulfur. Since the melted. sulfur is heavier than the water it sinks to the bottom of the sulfur bearing layer and collects near the bottom of the casing 9. A partition 12 prevents the incoming hot water from. mingling with the molten sulfur and acts as a bafile to direct it toward the upper part of the sulfur bearing layer. Additional perforations 13 in the side walls of the lower end of the casing 9 permit the molter sulfur to enter the lower end of the casing and to pass upwardly through the conduit 14 which is concentric with and inside of' conduit 9. The pressure in conduit 14 is lower than the pressure in conduit 9 and the column of molten sulfur inside of conduit 14 is lifted toward the. surface.

The hot gases of combustion and any auxiliary gases that may have been introduced into the system in the manner previously described pass downwardly in the passageway between conduit 14 and the inside of the casing 9 around the baffle l5, thence upwardly through the openingv 16 and the perforations or openings 17 into conduit 14 where. they assist in lifting the molten sulfur to the surface of the ground. Thus the gases of combustion are utilized in recovering the desired product. At the same time, the heat stored in these gases is utilized in maintaining the sulfur in a molten state. The sulfur is recovered in any suitable manner, for example, by running it to a storage pit 13 from which it can be taken and processed or stored as desired.

In Figure 2 there is illustrated a modification of the gas lock hood characterized by the fact that the bathe member 15 is tapered at the points. 19 and 19 in order to facilitate streamline flow of the gases and to minimize the possibilities of snagging while lowering or raising conduit 14.

The submerged combustion burner 1, which is illustrated diagrammatically in the drawings is preferably of the type described in See et al. U. S. Patent 2,118,479. In the type of burner shown a fuel gas such as natural gas or other suitable type of fuel gas is introduced through a pilot gas conduit 20 and a main gas conduit 21. Support for combustion is provided through a main air conduit 22 and a pilot air conduit 23. The combustion occurs at a burner plate 24 located within the combustion chamber 25. The operation of the submerged combustion burner can be controlled automatically in a number of different ways but the controls do not form a part of the invention and therefore they will not be discussed in detail. The conduits 4, 5, 7 and 8 are all provided with suitable valves and check valves (not shown) to control the flow of fluids therethrough.

Although the invention has been specifically illustrated for the mining of sulfur the apparatus described and the method can also be used for the mining of other materials which are capable. of being melted, thinned or dissolved, as the-case may be. Thus, petroleum bearing subsurface layers can be mined in accordance with the practice of the invention. The procedure is essentially the same as that previously described except that a petroleum residuum is substituted for the water 2 in he heat exchanger 3. A suitable residuum for this purpose is that obtained from the bottom of a petroleum fractionation tower. Other materials which are compatible with petroleum or which are solvents for petroleum can be used instead of the petroleum residuum. The gas employed to support combustion in the submerged burner 1 is regulated so that it is just sufficient to support the combustion of the fuel. In this way there is no excess of oxygen to cause combustion of the petroleum residuum or other material contained in the heat exchanger 3. In many instances an excess of oxygen will be desired so as to raise the temperature by combustion of the petroleum residuum or other materials being used.

In large operations it is desirable to use tonnage oxygen containing about or more of oxygen instead of air in order to support combustion in the submerged burner 1. The use of either tonnage oxygen or compressed air results in combustion gases that are enriched by picking up inflammable gases and/or vapors during the exchange of heat. in the subsurface petroleum layer. This enriched gas can be recovered and used as a source of gas for generating heat by the submerged combustion burner 1 or for any other source of heat generation employed to generate heat to be imparted to the petroleum in the petroleum bearing subsurface layers. If the subsurface oil isheated sufiiciently, chemical changes occur similar to those in the above ground oil refining operations and thus it is possible to utilize the present invention to save costly oil refining equipment at or near the surface.

A variation of the method and apparatus illustrated in Figure 1 is shown in Figure 3 wherein the gas lock hood 15" is provided with an inlet opening 26 at the top thereof which permits the gases flowing through conduit 8 to enter the gas lock hood 15" above the ground. In other respects the apparatus is similar to that described in Figure 1.

Another variation of the method and apparatus is illustrated in Figure 4. In this embodiment of the invention the mining fluid and the combustion gases which have previously been heated in a heat exchange chamber 3 in the manner described with respect to Figure l and passed through a surge drum 6 are introduced into conduit 27 and passed downwardly into the ore body containing sulfur, salt, petroleum or other material capable of being melted, thinned or dissolved by the mining fluid. The ore body is melted, thinned or dissolved, as the case may me, by the mining fluid entering it through the opening 28 in conduit 27 and the released gases agitate the liquid ore body as they riseto escape through the openings 29. The liquid product passes through openings 29 as well as openings 30 and the gases move along with the molten or liquid material andassist in carryingsaid material to the surface through conduit 31. The desired product is then recovered in any suitable manner.

It will be noted that all of the aforesaid conduits are fluid tight except as indicated and are adapted to hold gases and liquids under superatmospheric pressures.

The temperature of the flame at the burner plate 24 will vary somewhat depending upon the fuel being used. Natural gas has a flame temperature of around 2900 F. and is one of the preferred fuels for the purpose of the invention. The temperature of the mining fluid can be controlled by the introduction of additional fluid through the inlet 4. In the mining of sulfur the temperature of the mining fluid is preferably around 325 to 340 F. In the mining of petroleum much higher temperatures can be used and the invention contemplates heating the mining fluid to temperatures of 550 F. and higher so that the temperatures in the subsurface regions are high enough to effect at least a partial refining of the petroleum. Cracking of petroleum oils occurs at temperatures of around 650 F. and higher. Gasification and vaporization occur at lower temperatures. In accordance with one embodiment of the invention the temperatures in the subsurface regions are raised to a point suflicient to obtain gasification, vaporization and/ or cracking of the petroleum oils.

In Figure another variation of the invention is illustrated wherein like numerals are applied to like parts of the apparatus described in Figure 1 with certain modifications. According to the modified system shown in Figure 5, water is heated in the heat exchange chamber 3 by means of the submerged burner 1 and then passed through the conduit 5 to the pressure vessel 6 where the incondensible gases separate and pass through conduit 7 to well conduit 9. The hot water in chamber 6 is at least partially recycled to heat exchange chamber 3 through a return line 32. An inlet line 4 is provided to introduce additional water into the system. One of the principal features of this system is that the liquefied or molten sulfur which has been mined previously is returned to the well and utilized as a part of the mining fluid. This is accomplished by passing molten sulfur from the well or from a storage pit 18, as shown in Figure 5, through line 35 to chamber 6. The sulfur being heavier sinks to the bottom of the chamber, there being a water layer 33 and a sulfur layer 34. The molten sulfur is then introduced into the well conduit 9. Booster pumps 36, 37 and 38 are provided in order to pump the respective materials through the various conduits. A check valve 39 and a regulating valve 40 are provided in order to control the introduction of water into the system through the conduit 4. Other valves can be provided as needed. In a similar manner the same system is applicable to the recovery of petroleum by returning a petroleum residuum to the well; in other words, when this system is adapted to petroleum the material designated by the numeral 34 would be a petroleum residuum or some other similar liquid material compatible with the petroleum which is to be recovered.

In a further modification of the invention a submerged burner 1 can be located directly in any of the well conduits, for example, in the well passage 9.

The invention has many advantages in the mining of sulfur and other materials found in subsurface regions and which are capable of being melted, dissolved or modified by a mining liquid. By means of the invention the cost of mining sulfur is reduced materially because the water does not need to be fresh water; the water does not have to be specially prepared and treated before heating; there are no boiler tubes required and for that reason tube cleaning is unnecessary. Additionally, the invention makes it possible to mine sulfur and other materials in subsurface regions with greatly reduced quantities of compressed air because the gases of combustion assist in lifting the molten sulfur or other material to be mined from the subsurface regions. The heat conservation derived from the direct introduction of the flame beneath the surface of the mining fluid and the introduction of the hot products of combustion into the mining fluid represents a material savings in fuel costs. The cost of equipment required to practice the invention is much less than that required where stationary boilers are used instead to heat the mining fluid. The space requirements for the appa ratus used in the practice of the invention are smaller than the space requirements where stationary boilers are employed to heat the mining fluid. The invention is readily applicable therefore to the mining of sulfur by means of apparatus located on barges from sulfur deposits located beneath bodies of water. The operation of the process has the additional advantage that the apparatus can easily be moved from one location to another and is applicable in small units for the working of smaller deposits which would not ordinarily be mined by conventional methods because of the high capital investment requirements for equipment.

The invention is hereby claimed as follows:

1. A method of subsurface mining substances which can be modified and brought to the surface by heat imparted thereto by a mining liquid which comprises heating a mining liquid and passing the heated liquid mixed with the gaseous products of combustion of the fuel used in heating the liquid into the subsurface region containing the substance to be mined whereby the substance to be mined is modified by the heated liquid, and removing said modified substance from said subsurface region with the assistance of said gaseous products of combustion by releasing said products of combustion from said liquid and contacting the released gases with said modified substances in said subsurface region.

2. A method of subsurface mining sulfur which comprises heating water and passing the heated water mixed with the gaseous products of combustion of the fuel used in heating the water into the subsurface regions containing the sulfur whereby the sulfur is melted, and removing the melted sulfur from said subsurface regions with the assistance of said gaseous products of combustion by releasing said gaseous products of combustion from said water and contacting the released gases with said molten sulfur in said subsurface region.

3. A method of subsurface mining substances which can be modified and brought to the surface by heat imparted thereto by a mining liquid which comprises heating said mining liquid by means of combustion of a fuel directly in contact with and beneath the surface of the liquid, passing the heated liquid mixed with products of combustion of said fuel which are released directly into the liquid into subsurface regions containing the substance to be mined whereby the substance to be mined is modified by the heated liquid, and removing said modified substance from said subsurface region with the assistance of said gaseous products of combustion by releasing said products of combustion from said liquid and contacting the released gases with said modified substances in said subsurface region.

4. A method of mining sulfur from a subsurface region which comprises heating water by means of combustion of a fuel directly in contact with and beneath the surface of the water, passing the heated water mixed with the products of combustion from said fuel which are released directly into said water under pressure to a subsurface region containing the sulfur to be mined and at a temperature sufliciently high to melt the sulfur, providing a passageway for the removal of said melted sulfur, separating at least a part of said gaseous products of combustion from said water, and releasing said separated gaseous products of combustion into said passageway to assist in lifting the melted sulfur from said subsurface region to the surface of the ground.

5. A method of subsurface mining substances which can be modified and brought to the surface by heat imparted thereto by a mining liquid which comprises heating a mining liquid and passing the heated liquid mixed with the gaseous products of combustion of the fuel used in heating the liquid under superatmospheric pressures into the subsurface region containing the substance to be mined whereby the substance to be mined is modified by the heated liquid, and removing said modified substance from said subsurface region with the assistance of said gaseous products of combustion by releasing said products of combustion from said liquid and contacting the released gases with said modified substances in said subsurface region.

6. A method of subsurface mining substances which can be modified and brought to the surface by heat imparted thereto by a mining liquid which comprises heating a mining liquid by means of combustion of a fuel directly in contact with and beneath the surface of the liquid, passing the heated liquid mixed with the gaseous products of combustion of the fuel used in heating the liquid from the heating zone into a second zone under superatmospheric pressure, releasing a part of the gaseous products of combustion in said second Zone, passing the eated liquid together with the remainder of said products of combustion from said second zone to a subsurface region containing the substance to be mined whereby the substance to be mined is modified by the heated liquid, and removing said modified substance from said subsurface region with the assistance of said gaseous products of combustion by releasing said products of combustion from said liquid and contacting the released gases with said modified substances in said subsurface region.

7. A process as claimed in claim 5 wherein additional gaseous fluid is added to said mining liquid under superatmospheric pressure at a point between said heating zone and said subsurface region.

8. In a system for mining substances from subsurface regions with a mining fluid, the combination of, means for heating said mining fluid in a closed heat exchange chamber, a surge drum comprising a closed fluid tight vessel, a passageway connecting said surge drum with said heat exchange chamber, means for releasing incondensible gases from said surge drum, inlet passageway means for passing a heated liquid and gaseous products of combustion from said surge drum to a subsurface region con taining a substance to be mined, outlet passageway means from said subsurface region to the surface of the ground for removal of the substance to be mined and means in said inlet passageway for separating said gaseous products of combustion from said heated liquid and for passing said separated gaseous products of combustion into the mined substance flowing in said outlet passageway.

9. In a system for mining substances from subsurface regions with a mining liquid, a combination of, means for heating said mining liquid in aclosed heat exchange chamber to produce a heated mining liquid and gaseous products of combustion, inlet passageway means for passing said heated liquid and at least a portion of said gaseous products of combustion to a subsurface region containing a substance to be mined; outlet passageway means from said subsurface region to the surface of the ground for removal of the substance to be mined and means for bleeding said gaseous products of combustion from said inlet passageway into said mined substance flowing in said outlet passageway at a point above the lowermost end of said outlet passageway.

References Cited in the file of this patent UNITED STATES PATENTS 1,217,065 Rhodes Feb. 20, 1917 1,846,358 Reed Feb. 23, 1932 2,172,683 Reed Sept. 12, 1939 2,489,491 Johnson Nov. 29, 1949 2,584,606 Merriam et al Feb. 5, 1952 2,647,370 Miller Aug. 4, 1953

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1217065 *Feb 18, 1916Feb 20, 1917Hampton P RhodesMethod of mining sulfur and other minerals.
US1846358 *Oct 27, 1930Feb 23, 1932Reed Warren BProcess of mining sulphur
US2172683 *Aug 10, 1937Sep 12, 1939f eleven and oneMining process
US2489491 *Jan 12, 1946Nov 29, 1949Lou Son Dev CoPulsation absorber
US2584606 *Jul 2, 1948Feb 5, 1952Frederick SquiresThermal drive method for recovery of oil
US2647370 *Jan 31, 1950Aug 4, 1953Jefferson Lake Sulphur CoWater heating system
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2847201 *Nov 9, 1954Aug 12, 1958Carroll R GrahamPortable sulphur plant for use in a region of subsidence
US2991987 *Dec 31, 1956Jul 11, 1961Submerged Comb IncProcesses for heating a mining liquid and mining therewith a substance modified by heat
US3027320 *Sep 14, 1959Mar 27, 1962Phillips Petroleum CoRemoving salt from sea water
US3196947 *Jun 14, 1962Jul 27, 1965Marathon Oil CoMethod for facilitating the production of viscous petroleum through a well
US3620571 *Jun 16, 1969Nov 16, 1971Billings Calvin HSingle-well heated gas mining method and apparatus
US3986558 *Jan 21, 1975Oct 19, 1976Francois DufourPetroleum extraction method and assembly
US4113017 *Dec 9, 1976Sep 12, 1978Phillips Petroleum CompanyHot effluent from partial oxidation of natural gas injected in oil recovery process
US4157847 *Jul 28, 1977Jun 12, 1979Freeport Minerals CompanyMethod and apparatus for utilizing accumulated underground water in the mining of subterranean sulphur
US4398604 *Apr 13, 1981Aug 16, 1983Carmel Energy, Inc.Method and apparatus for producing a high pressure thermal vapor stream
US4399865 *Jul 20, 1981Aug 23, 1983Chevron Research CompanyConcentric steaming string downhole apparatus
US4497635 *Dec 1, 1982Feb 5, 1985Rodger BlackwoodSulfur remelting
US4753485 *Jul 18, 1986Jun 28, 1988Hydril CompanySolution mining
US4869555 *Jan 6, 1988Sep 26, 1989Pennzoil Sulphur CompanyApparatus for recovery of sulfur
US4896725 *Jun 13, 1988Jan 30, 1990Parker Marvin TIn-well heat exchange method for improved recovery of subterranean fluids with poor flowability
US8561702Feb 11, 2008Oct 22, 2013Vast Power Portfolio, LlcHot fluid recovery of heavy oil with steam and carbon dioxide
WO1989012728A1 *Jun 13, 1989Dec 28, 1989Marvin T ParkerIn-well heat exchange method for improved recovery of subterranean fluids with poor flowability
Classifications
U.S. Classification299/6, 166/303
International ClassificationE21B43/285, E21B43/00
Cooperative ClassificationE21B43/285
European ClassificationE21B43/285