Stimulating production from oil wells using an rf dipole antenna

A method of increasing permeability of a volume of a formation adjacent to a buried RF dipole antenna structure comprising:

• forming a borehole into or adjacent to said formation;
• and
• emplacing into said borehole an inner and an outer coaxially disposed tubular conductors, the conductors each being connected at an earth surface to an RF power source, the conductors forming a coaxial transmission line proximate the earth surface and a dipole antenna proximate said formation, said inner conductor protruding from said outer conductor from a junction exposing a gap between said inner and said outer conductors to a deeper position within said formation, said RF power source being configured to deliver, via the conductors, RF fields to said formation, and heating said formation to a temperature of at least about 270° C., at which temperature organic material within said formation is converted to oil and gas, thereby opening pores in said formation and increasing the permeability to fluid flow.

A method of producing channels for fluid flow in a volume of a formation adjacent to a buried RF dipole antenna structure comprising:

• forming a borehole into or adjacent to said formation;
• and
• emplacing into said borehole an inner and an outer coaxially disposed tubular conductors, the conductors each being connected at an earth surface to an RF power source, the conductors forming a coaxial transmission line proximate the earth surface and a dipole antenna proximate said formation, said inner conductor protruding from said outer conductor from a junction exposing a gap between said inner and said outer conductors to a deeper position within said formation, said RF power source being configured to deliver, via the conductors, RF fields to said formation so as to heat said formation adjacent to said antenna to a temperature of at least 270° C., at which temperature differential thermal expansion of said formation produces stresses which cause fractures to form in said formation adjacent said antenna, and thereby to produce channels for fluid to flow into said inner conductor.

A method of increasing recovery of oil in a steam-assisted gravity drive method, by pretreating a volume a formation adjacent to a buried RF dipole antenna structure, the method comprising:

• forming a borehole into or adjacent to said formation;
• and
• emplacing into said borehole an inner and an outer coaxially disposed tubular conductors, the conductors each being connected at an earth surface to an RF power source, the conductors forming a coaxial transmission line proximate the earth surface and a dipole antenna proximate said formation, said inner conductor protruding from said outer conductor from a junction exposing a gap between said inner and said outer conductors to a deeper position within said formation, said RF power source being configured to deliver, via the conductors, RF fields to said formation, and heating said formation adjacent to said borehole to a temperature of at least about 270° C., so as to develop permeability along the length of said borehole, to provide a path for steam to flow from a whole length of said borehole into said formation.