This is the second article in a series reviewing 2016 patents focused on Enhanced Oil Recovery (EOR). This article relates to the use of radiation energy in oil recovery. For Part I in the series, Click Here.

Enhanced oil recovery techniques can loosely be grouped into methods conducted at ambient temperatures and those at high temperature. Ambient temperature methods include techniques using water flooding, solvent or surfactant injection, and cold heavy oil production with sand (CHOPS). High-temperature techniques function by heating recoverable material in the reservoir to lower its viscosity and improve flowability. Such techniques typically use steam, i.e., steam injection in various ways, although radiation assisted oil recovery would also fall into this group. However, while conventional heat treatments using steam are effective, they can sometimes result in a wastewater stream that is not desirable. While radiation techniques may additionally utilize other injectable streams, they need not rely on a separate heat-input stream to transfer heat, so typically don’t generate the wastewater streams characteristic of steam injection.

The following three references illustrate EOR patents that issued in 2016 relating to radiation-assisted methods. Attached Table 1 lists relevant information on the EOR-Radiation patents reviewed. Table 2 contains a representative independent claim from each.

U.S. Patent No. 9,297,240 generally relates to an EOR method using cyclic radio frequency (RF) energy. The patent has a total of 19 claims with 4 independent claims (1, 8, 16, and 19). The radio frequency utilized is the frequency of electrical signals to produce radio waves (30 KHz to 300 GHz). In particular, the radio frequency of the electromagnetic energy used is in the radio frequency range (0.001 MHz to 30 MHz). The method includes first applying RF energy at a first power level in a reservoir to create a dessication region, where water has been evaporated. Then the RF energy is reduced 75-100% from the first power level for a soak period, (e.g., 2+ days, preferably 4-5 days) to facilitate heat transfer into the reservoir. The radiation/soak steps are then repeated and the hydrocarbon is recovered. The radiation cycles can also be accompanied by cyclic steam injection.

U.S. Patent No. 9,341,050 generally relates to a process for oil recovery from heavy hydrocarbon crude oil reserves using microwave energy. The patent has a total of 17 claims with 2 independent claims (1 and 10). The claimed process uses a horizontal injection well, a horizontal microwave source well, and a horizontal production well, where the injection horizontal run is positioned below both the microwave source horizontal run and the production horizontal run, and the microwave source run is positioned between the injection horizontal run and the production horizontal run. A treatment fluid containing a miscible solvent for heavy hydrocarbons is introduced into the crude oil reservoir through the horizontal injection well, then a microwave antenna having a microwave emitter is made into the horizontal microwave source well. Electrical power is introduced into the microwave emitter so that microwave energy is directed to the portion of the formation being treated. Production fluid is then extracted from the formation through the horizontal production well.

U.S. Patent No. 9,458,709 generally relates to a process for heavy oil production using electromagnetic radiation for preheating, along with gas injection in systems of production wells and gas injection wells. The patent has a total of 23 claims with three independent claims (1, 10 and 19) In the process, prior to gas injection a radio frequency (RF) generator provides electromagnetic energy to antennae located downhole in an oil reservoir, where at least one of the antennae is located between the production and gas injection wells. The gas remains in the reservoir for the duration of the oil recovery process, and can include air, CO2, N2, methane, ethane, propane, butane, flue gas and combinations thereof.

Table 1 — EOR Patents — Radiation-Assisted

Patent Number Inventor Assignee Title Issue Date
U.S. 9,297,240 Sultenfuss et al. ConocoPhillips Co. & Harris Corp. Cyclic Radio Frequency Stimulation March 29, 2016
U.S. 9,341,050 Khaled Abdullah Al-Buraik Saudi Arabian Oil Company Utilization Of Microwave Technology In Enhanced Oil Recovery Process For Deep And Shallow Applications March 17, 2016
U.S. 9,458,709 Sultenfuss et al. ConocoPhillips Co. & Harris Corp. Heavy Oil Production With EM Preheat And Gas Injection October 4, 2016

Table 2. — Enhanced Oil Recovery — Radiation-Assisted

Patent Number Independent Claim
U.S. 9,297,240 Claim 1. A method for enhanced oil recovery using cyclic radio frequency (RF) in a hydrocarbon reservoir, said method comprising: i) providing RF energy at a first power level in a hydrocarbon reservoir to create a dessication region in said hydrocarbon reservoir, ii) allowing a soak period during which RF energy is reduced by 75-100% of said first power level, and iii) repeating steps i-ii) one or more times; and iv) subsequently collecting hydrocarbon from said hydrocarbon reservoir at one or more times.
U.S. 9,341,050 Claim 1. A method for treating a portion of a hydrocarbon-bearing formation of a crude oil reservoir containing heavy hydrocarbons using a microwave enhanced heavy hydrocarbon recovery system, the process of heavy hydrocarbon recovery comprising the steps of: forming a horizontal injection well that is defined by a horizontal injection well bore wall that extends from a surface to below a lower boundary of the crude oil reservoir, that is operable to permit fluid communication between the surface and the crude oil reservoir, and that is operable to permit the introduction of a treatment fluid into the crude oil reservoir, where a portion of the horizontal injection well is an injection horizontal run that has a casing along the horizontal injection well bore wall, and where the casing along the horizontal injection well bore wall is operable to permit fluid communication between the horizontal injection well and the crude oil reservoir; forming a horizontal microwave source well that is defined by a horizontal source well bore wall that extends from the surface to the lower boundary of the hydrocarbon-bearing formation, that is operable to permit communication between the surface and the hydrocarbon-bearing formation, and that is operable to permit the introduction of microwave energy into the crude oil reservoir, where a portion of the horizontal microwave source well is a microwave source horizontal run that has a casing along the horizontal source well bore wall that extends proximate to the lower boundary, and where the casing along the horizontal source well bore wall is operable to permit energy communication between the horizontal microwave source well and the crude oil reservoir; forming a horizontal production well that is defined by a horizontal production well bore wall that extends from the surface into the hydrocarbon-bearing formation, that is operable to permit fluid communication between the surface and the hydrocarbon-bearing formation, and that is operable to permit the extraction of a production fluid from the hydrocarbon-bearing formation, where a portion of the horizontal production well is a production horizontal run that has a casing along the horizontal production well bore wall, and where the casing along the horizontal production well bore wall is operable to permit fluid communication between the horizontal production well and the hydrocarbon-bearing formation; introducing a treatment fluid into the crude oil reservoir through the horizontal injection well such that the treatment fluid passes into the portion of the hydrocarbon-bearing formation to be treated, where the treatment fluid comprises an aqueous solution with a miscible solvent for the heavy hydrocarbons; introducing a microwave antenna having a microwave emitter into the horizontal microwave source well such that the microwave emitter is located in the microwave source horizontal run and such that the microwave emitter is operable to direct microwave energy towards the portion of the hydrocarbon-bearing formation to be treated, wherein the horizontal microwave source well is a separate from the horizontal injection well and the horizontal production well; introducing electrical power to the microwave emitter such that microwave energy is directed towards the portion of the hydrocarbon-bearing formation to be treated, such that a microwave energy field forms that envelopes the portion of the hydrocarbon-bearing formation to be treated, such that the viscosity of the heavy hydrocarbons located within the microwave energy field is reduced, and such that the production fluid forms within the microwave energy field, where the production fluid comprises the heavy hydrocarbons with reduced viscosity and the treatment fluid; and extracting the production fluid from the hydrocarbon-bearing formation through the horizontal production well; where the injection horizontal run is positioned below both the microwave source horizontal run and the production horizontal run, and the microwaves source run is positioned between the in injection horizontal run and the production horizontal run.
U.S. 9,458,709 Claim 1 An improved gas injection oil recovery process comprising one or more producer wells and one or more gas injector wells, wherein injection of a gas into said gas injector wells drives oil towards said one or more producer wells for production of said oil, the improvement comprising preheating said oil with electromagnetic radiation so as to provide fluid communication between said producer well and said injection well before said gas injection; wherein said electromagnetic energy is provided by RF generator coupled via transmission lines to one or more antennae placed downhole in an oil reservoir, wherein at least one of said one or more antennae is located between wells, and wherein said gas is selected from the group consisting of air, CO2, N2, methane, ethane, propane, butane, flue gas and combinations thereof, and wherein said injected gas remains in the reservoir for the duration of the oil recovery process.