System and method for extraction of hydrocarbons by in-situ radio frequency heating of carbon bearing geological formations

Abstract

A method of producing liquid hydrocarbons from a hydrocarbon-bearing rock in situ in a geological formation begins with exploring the formation by drilling a plurality of boreholes into the formation and taking core samples of the hydrocarbon-bearing rock and at least one overburden layer. Electrical parameters of the hydrocarbon-bearing rock and the overburden layer are determined, as well as a roughness of a boundary between the hydrocarbon-bearing rock and the at least one overburden layer. These electrical parameters are used to construct a computer model of a portion of the hydrocarbon-bearing rock and at least one overburden layer, the computer model based upon modeling the formation as a rough-walled waveguide. This computer model is used to simulate propagation of radio frequency energy within the hydrocarbon-bearing rock, including simulation of radio frequency wave confinement within the hydrocarbon-bearing rock, at several frequencies and temperatures. A frequency for retorting is selected based upon simulation results. Radio frequency couplers are installed into at least one borehole in the hydrocarbon-bearing rock and driven with radio frequency energy to heat the hydrocarbon-bearing rock. As the rock heats, it releases carbon compounds and these are collected.

Description

RELATED APPLICATIONS[0001]The present application claims the benefit of priority to Provisional Application Ser. No. 60 / 976,314 filed Sep. 28, 2007, and is incorporated herein by reference.FIELD[0002]The present apparatus and method relates to the extraction of hydrocarbons from hydrocarbon-bearing geological formations. In particular, the method is applicable to extraction of hydrocarbons from oil-shale and tar sands, and may also be useful in enhanced oil recovery from oil fields.BACKGROUNDFormations Bearing Low Motility Carbon Compounds[0003]Many carbon and hydrocarbon-bearing geological formations contain carbon-containing compounds that lack sufficient mobility for tapping with simple wells. For example, oil-shales, tar sands, hydrocarbon-bearing shale, and low-grade coal are carbon-bearing sedimentary rocks containing carbon compounds that do not migrate efficiently into wells for recovery under ordinary conditions.[0004]Oil shale is a general term applied to a group of fine b...

AI Technical Summary

Problems solved by technology

Many carbon and hydrocarbon-bearing geological formations contain carbon-containing compounds that lack sufficient mobility for tapping with simple wells.

Ex-situ retorting is widely recognized as posing considerable environmental problems due to the surface disturbance involved with mining and disposal of spent rock; it also requires much labor and heavy machinery.

In-situ and modified in-situ retorting experiments have not been wholly successful.

Mining and surface retorting of these deposits has many potential environmental consequences, risks, and costs.

The in-situ method of Berchenko requires close to 100% surface disturbance, greatly increasing the footprint of extraction operations in comparison to conventional oil and gas drilling, in part because of the large number and close spacing of freeze-wall, heating, and production wells required.

The bitumenous hydrocarbon content of these deposits is relatively immobile under ordinary conditions, such that primary recovery is slow and may yield less than eight percent of the hydrocarbon content of the rock.

Secondary recovery, typically involving injecting water under pressure, yields another 10-20 percent; however, this water can present a significant waste disposal problem as the water may be pumped out of the well with the oil.

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