System For Extraction of Hydrocarbons Underground

摘要

A system for in-situ heating of a subsurface formation for the extraction of hydrocarbons in underground deposits is disclosed. The system is configured to heat the underground deposit of hydrocarbons to facilitate fluid flow and hydrocarbon recovery from the underground deposit. The system has an antenna formed from a coaxial transmission line having an annular space between the transmission line outer conductor and the inner conductor and having one or more periodic aperture arrangements along the axial length of the outer conductor. A method for in-situ heating of a subsurface formation for recovering hydrocarbons contained therein is also disclosed. The method comprises: providing an antenna in the subsurface formation; providing electromagnetic RF power to the antenna for heating at least a portion of the subsurface formation.

主权项

1. A coaxial antenna for radio frequency (RF) in-situ heating of a subterranean formation, the formation having a 1st relative electrical permittivity and an electrical conductivity, the antenna having at least an antenna section comprising:
an outer conductor having a longitudinal axis and having a circular cross-section having an inside diameter perpendicular to the longitudinal axis, and further having at least one aperture; an inner conductor that is coaxial to the outer conductor and having a circular cross-section having an outside diameter; and an annular space defined by the inside diameter of the outer conductor and the outside diameter of the inner conductor, the annular space containing a dielectric material having a 2nd relative electrical permittivity that is less than the 1st relative electrical permittivity; wherein a ratio b/a of the inside diameter of the outer conductor (b) and the outside diameter of the inner conductor (a) remains uniform along the longitudinal axis for a constant characteristic impedance, and wherein the b/a ratio ranges from 1.5 to 10; wherein the at least one aperture is arranged for the antenna to have a circumferential radiation of at least 180 degrees along the longitudinal axis; wherein the antenna has an operational RF power signal frequency from 5 kHz to 20 MHz; wherein the antenna has a radiation power from 0.5 kW/m to 50 kW/m per longitudinal length of the antenna, wherein the 1st relative electrical permittivity ranges from 2.5 to 1000 and the electrical conductivity of the formation ranges from 5.0 S/m to 4×10−4 S/m.