Patent Application
20140096958
Embodiments of the present invention are generally directed toward enhanced oil and gas production by means of the thermal stimulation of formation hydrocarbons in situ or in the wellbore during production.
It is well known in the oil and gas industry that production from oil wells will increase upon heating the oil and thereby lower the viscosity of that oil. This is especially true for the more viscous heavy oil and tar sand deposits where incremental changes in temperature can lead to an order of magnitude change in viscosity. To date there have been but a few successful thermal methods utilized for production from heavy oil deposits. Those being fire flooding and steam based methods including: Cyclic Steam Stimulation (CSS), steam flooding and Steam Assisted Gravity Drainage (SAGD). The steam methods are economically and thermodynamically constrained to deposits shallower than around 3000 ft (DOE Office of Petroleum Reserve—Strategic Unconventional Fuels, Jun. 18, 2007. Fact Sheet: U.S. Heavy Oil Resource Potential). Whereas, fire flooding involves the injection of oxygen in the form of air typically and depending upon the specifics of the formation water may also be injected. Although the fire flooding method has produced very desirable results in some cases it suffers from two main problems. The first of which is safety related in that the oxygen utilized can be an unwanted fire and explosive hazard when combined with natural gas either at the injection well or at the production well. Another issue with fire flooding technology is the use of a gaseous oxidizer in which the compressor horse power requirements and available installed well casing place a depth limit of utilizations to shallower formations. It is estimated that in the U.S. alone there are almost 100 billion barrels of “heavy oil” resource of original oil in place (DOE Office of Petroleum Reserve—Strategic Unconventional Fuels, Jun. 18, 2007. Fact Sheet: U.S. Heavy Oil Resource Potential). Hence, a significant resource remains out of technical reach. What is needed is a method to safely produce energy in the form of heat where it is needed: down hole and at depths greater than 3,000 ft and as far as the drill bit can go. This fact is and has been well recognized by the U.S. government noting that “Project Deep Steam” was conducted in the late 1970's. The program followed two paths: The first attempting to produce well bore tubulars with better insulation capability so that surface steam could be injected further. The second path was to make a combustor that operated down hole which was fed propellants from the surface, namely diesel and oxygen (air). The down hole steam generator portion of the program is documented in technical report: B. W. Marshall, Sandia National Laboratories, May, 1983. SAND83-0145/I, Field Test of Two High-Pressure, Direct Contact Downhole Steam Generators, Vol I. Air/Diesel System. Both of these efforts produced minor technical success but only the down hole combustor was utilized in a short lived commercial operations and at that was utilized no deeper than 2500 ft (A. B. Donaldson, 1997. SPE 38276, Reflections on a Downhole Steam Generator Program, 1997 SPE Regional Meeting, Long Beach, Calif., 25-27 Jun. 1997).
In addition there are at present electrical bottom hole heaters which are also restricted to fairly shallow depths and suffer from a major heat transfer defect in that the produced flow takes the heat away from bottom hole where it is needed (Prats, M., 1985. Thermal Recovery. 2nd ed. Richardson, Tex.: SPE Monograph Series, Volume 7, pp. 119-121).
The present disclosure discloses inter alia a method whereby a liquid oxidizer can be safely delivered to any presently known depth that a liquid fuel may also be delivered. There does exist prior methods for delivery of liquid oxidizers to bottom hole locations. Smith teaches a method to deliver hydrogen peroxide (U.S. Pat. No. 8,047,285 and U.S. patent application Ser. No. 12/424,376 and Ser. No. 13/028,883). The present disclosure is superior to this prior method utilizing hydrogen peroxide, for example, in that hydrogen peroxide can create oil field hazards by several means. The primary of these hazards being that oxygen is produced by decomposing the hydrogen peroxide from which if the system is improperly operated may form a combustion/explosive mixture with methane either down hole or in the production lines. While the intention would be to consume all of this oxygen an explosion hazard is still present and must be accounted for. Example embodiments of the present disclosure utilize what is known to those in the art as a “selective oxidizer,” or an oxidizer that will only be made to react with particular compounds and ignore or greatly reduce reaction with others. This disclosure teaches example embodiments using a selective oxidizer composition that is non-selective with respect to alkane chemistry. This use greatly increases the safe operation in a fuel rich environment such as a hydrocarbon reservoir given that almost all produced hydrocarbons are of alkane chemistry. In addition in certain aspects of the aforementioned Smith patents and applications (U.S. Pat. No. 8,047,285 and U.S. patent application Ser. No. 12/424,376 and Ser. No. 13/028,883) make use of energy release from decomposition of hydrogen peroxide using a catalyst whereas the present disclosure does not require the presence of catalyst for reaction and heat release.
Embodiments of the present invention are related to enhanced production of hydrocarbons from hydrocarbon bearing subterranean formations. More specifically enhanced production is achieved, for example, by thermal stimulation of a wellbore bottom hole, near the wellbore, and/or far afield in the formation depending upon the specific embodiment apparatus. The present invention is novel in that, for example, bottom hole and reservoir energy release is accomplished by reaction of selective oxidizers that are non-selective toward alkane chemistry. Hence, selective oxidizers are nonreactive with a vast majority of naturally occurring reservoir and produced hydrocarbons resulting in a much safer production of hydrocarbons from subterranean formations than existing methods of oxidizer utilization in the oil and gas industry. This novelty, for example, further increases the depth at which oxidizers can be deployed in subterranean formations, for example such depth being limited only by the reach of a drill bit.
The present invention in one of its simplest embodiments, for example, would consist of a system in which two separated tanks would rest upon the surface of the earth near an existing wellbore which is utilized for hydrocarbon production. One of the tanks would hold a liquid fluid system containing an oxidizer which is non-selective toward alkane chemistry. The second tank would hold a liquid fluid system containing a fuel which would be chemically non-alkane. These two liquids would be pumped through separate fluid conduits which are inside the aforementioned well bore or one of the fluid conduits being the aforementioned well bore. The two liquids would be pumped simultaneously and in chemical proportion to maximize energy release. The two separate fluid conduits would only permit the two fluid systems to come into contact at a desired down hole location. After the two fluid systems contact one another they will mix, react and produce energy heating the nearby materials. In addition, for example, the energy release or any possible water insoluble reaction products can be utilized for other fluid mechanical operations.
It is to be expressly understood, however, that the embodiments described herein, and each of the figures, are provided as examples and for the purpose of illustration and description only and they and use of the terms such as “the invention” or “the present invention” are not intended as a definition of the limits of the scope or embodiments of the invention. The priority application or any changes or differences, including any typographical or grammatical changes, between the present disclosure and priority to U.S. Provisional Patent Application No. 61/795,016 should not be read to limit or impair the scope of the present disclosure.
As used herein, “a” or “an” includes one or more. Where the present disclosure refers to “perforations” it should be understood to include “one or more perforations.”
As used herein, “surface” or “surface of the earth” refers to locations approximately at, or at or near the surface of the earth.
As used herein, “hydraulic fracturing” refers to a method of injecting a fluid above the fracture pressure of a subterranean reservoir into which the fluid is injected, or any propagation of fractures in a reservoir in strata (e.g. a rock layer) as a result of a pressurized fluid.
As used herein, “stimulation” refers to a method of injection a fluid below the hydraulic fracture pressure of a reservoir wherein the fluid is being injected.
As used herein “proppant” refers to any solid material that has sufficient strength to resist the overburden forces of the earth in a reservoir into which it is introduced or pumped, for example, any material that will keep a hydraulic fracture open, during or following a fracturing treatment, including for example particles which are permeable or primitive to gas.
As used herein “fluid system” refers to fluids that contain chemicals, and/or catalyst, and/or proppants.
As used herein “conduit” refers to a fluid transmission path that contains a fluid and any pressure of such a fluid.
As used herein “strata” includes a particular depth below the surface of the earth of solids, liquids, and gas constituents that comprise the earth. Strata as used herein refer to any and all particular subterranean depths.
As used herein the term “reservoir” includes a deposit of substances in any formation, stratum or strata.
As used herein “fluid” or “fluids” is defined as any liquid, plasma, gas, gel, foam, slickwater, or other substance that can deform, for example, under shear stress.
As used herein “alkane” refers to chemical compounds that consist only of hydrogen and carbon atoms and are bonded exclusively by single bonds without any cycles. Also know as a saturated hydrocarbon. Examples include methane, ethane, propane containing one, two and three carbon atoms respectively. Alkanes and Cycloalkanes are presently known to represent approximately 80% of the average crude oil composition depending upon specific natural deposits (Wikipedia, 2012. Petroleum. Available at: <http://en.wikipedia.org/wiki/Petroleum> as of Dec. 4, 2012.) Whereas, for example, the hydrocarbons present in natural gas and natural gas liquids are almost completely alkane chemistry depending upon specific natural deposits.
As used herein “alkene” refers to chemical compounds that consist only of hydrogen and carbon atoms containing at least one carbon-to-carbon double bond. Also known as unsaturated hydrocarbons. These chemical compounds are typically industrially produced by hydrocarbon cracking of natural gas liquids.
As used herein “alkyne” refers to chemical compounds that consist only of hydrogen and carbon atoms containing at least one carbon-to-carbon triple bond.
As used herein “alcohol” refers to organic chemical compounds containing at least one hydroxyl group bonded to a carbon atom. Examples are ethanol, methanol and glycerol which is a polyol (an alcohol having more than one hydroxyl group).
As used herein “selective oxidation” refers to the preferential attack by oxygen within an oxidizing agent on one or more of the chemical components in a material.
Embodiments of the present invention relate to use of thermal energy to increase recovery of subterranean hydrocarbons and ultimately to increase hydrocarbon recovery from a specific formation or strata. The embodiments of this invention, for example, direct energy where it is most efficiently utilized in the near bottom hole, near well bore, and far afield in the formation from the well bore. The example embodiments outlined in the present disclosure are directed toward deep (>3000 ft) heavy oil, high paraffin content crude oils, oil sands, high kerogen strata such as oil shale where increases in local temperature result in significant changes in fluid viscosity. However, embodiments of the present invention may also find use with, for example but not limited to, hydraulic fracturing and enhanced oil recovery due to the nature of the products of reaction.
In one embodiment the energy is released near well bore and the reaction products are comingled with the fluids produced from a formation resulting in increased temperature and better flow assurance of formation fluids including hydrocarbons up the wellbore to the surface of the earth. In another embodiment the energy is released partially in the well bore near the perforations through the well casing allowing fluid communication between the wellbore and the formation and also near the well bore out into the formation depending on flow rates and reaction rates. This release of energy results, for example, in near wellbore heating of fluids, and after a heat soaking period the reaction products and formation hydrocarbons are then produced to the surface of the earth.
In one embodiment the energy is released partly in the wellbore but mostly in the near well bore and far afield in the formation. In this embodiment, the far afield is heated and swept with the reaction products and is produced out of another well, for example. Additionally, in this embodiment acidic reductive leaching agents may also be injected into the formation or near locations where the selective oxidizer reactions have occurred in order to react with reaction products of the first energy producing reaction.
Attention is first directed to
It is understood that known aspects of hydraulic fracturing can be used in conjunction with embodiments of the present invention. As such, in addition, fluid 14 and/or fluid 15 of
In another preferred embodiment, members of the permanganate family are selected at least in part as the selective oxidizing agents in fluid 14 of
3 C3H5(OH)3+14 KMnO4+358.7 H2O→14 MnO2+14 KOH+9 CO2+363.7 H2O
In an additional embodiment, one of the reaction products 17 of
24 MnO2+C12H22O11+24 HSO4→24 MnSO4+12 CO2+35 H2O
As described, embodiments of the present invention are fundamentally different than other prior methods such as those disclosed in U.S. patent application publications nos. US2012/0160486, US2012/0175114, US2012/0175115 & US2012/0175116 which utilize permanganates in the subterranean environment. For instance, these prior disclosures relate to the use of oxidizers for chemical modification of in situ kerogen. As such, permanganates are mentioned merely as an example of an oxidizer and make no mention of the use of selective oxidizers, for example. In addition, the mentioned prior disclosures differ from embodiments of the present invention in that the prior disclosures use a fuel that is already in the formation, whereas an embodiment of the present invention, for example, utilizes a fuel which is pumped down from surface and is at least partially a non-alkane chemical. A further difference is that embodiments of the present invention, for example, relate to energy generation down hole to create temperature changes whereas the aforementioned prior disclosures relate only to chemical manipulation.
U.S. Pat. No. 4,648,835 discloses a bottom hole combustor design utilizing air, water and fuel from surface, and ignition methods and chemistry to make steam in the well bore down hole. Example embodiments of the present invention teaches new and novel aspects not covered under said patent, those being delivery of a selective oxidizer that is non-selective toward alkanes, for example. U.S. Pat. No. 4,648,835 utilizes air containing oxygen that will oxidize with alkane chemistry whereas, for example, the present invention will not prefer to oxidize alkane chemical fuels. In addition, example embodiments of the invention disclosed herein inject a liquid fluid, for example, whereas the aforementioned U.S. patent uses gaseous oxidizers. In addition, in the aforementioned U.S. patent, energy release is inside the well bore whereas in example embodiments of the present invention energy release may occur at least partially out into the formation, for example.
U.S. Pat. No. 5,004,050 utilizes oxidizers inside a device placed inside the well bore as a portion of dielectrics that are set off by electrical discharge thereby creating a shockwave that travels into the formation, where such oxidizers are in some specific mentions similar to oxidizers in example embodiments of the invention herein. Example embodiments of the present invention, however, are different in that oxidizers are utilized to create thermal energy and not as dielectrics for creation of pressure energy, for example. In addition the method described by U.S. Pat. No. 5,004,050 utilizes oxidizers and not selective oxidizers as is the case for the present invention.
U.S. Pat. No. 5,967,233 discloses pumping liquid oxidizers, which in some specific mentions are similar to example embodiments of the invention herein, into a coal formation and permitting the oxidizer to react with the formation resulting in increased methane production. Example embodiments of the present invention, however, are different in that they utilize selective oxidizers which are non-selective to alkanes, for example, and in addition would likely not react as in the method described by U.S. Pat. No. 5,967,233. In addition, example embodiments of the present disclosure are for release of energy in subterranean environment rather than chemical modification of reservoir fuels and, in addition, example embodiments of the present invention utilize at least in part non-alkane fuels pumped down hole from the surface and do not utilize in situ fuels, for example.
U.S. patent application publication no. US2009/0130732 discloses use of oxidizers that in some specific mentions are similar to those in embodiments of the invention herein but the aforementioned publication is for chemical manipulation of heavy oils on the surface of the earth after having been physically removed from the subterranean environment, whereas example embodiments of the present invention do not chemically change the down hole hydrocarbons, for example. And, in addition, example embodiments of the present invention are for the generation of energy down hole, whereas the aforementioned publication does not, for example.
Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions, additions, and alterations can be made herein without departing from the spirit and scope of the present disclosure, and/or as defined) by the appended claims. As one of ordinary skill in the arts of hydrocarbon extraction, water extraction, mining, and oxidation reactions will readily appreciate from the disclosure of the present disclosure, processes, devices, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, one or more of the appended claims can include within their scope such processes, devices, manufacture, compositions of matter, means, methods, or steps.
This application claims priority to U.S. Provisional Patent Application No. 61/795,016, filed Oct. 9, 2012 entitled, “Method, Apparatus and Composition to Increase Recovery of Hydrocarbons by Selective Oxidation of Fuels in the Subterranean Environment” and the disclosure of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61795016 | Oct 2012 | US |
