Conduction heating of hydrocarbonaceous formations

A method for the in situ heating of an earth formation having substantial electrical conductivity, said method comprising:

• bounding a particular volume of said formation with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array wherein said electrodes are disposed parallel to and adjacent respective boundaries of said formation and the length and width of the active electrode area are large relative to the thickness of said formation to avoid heating barren layers, and said row of electrodes adjacent the upper boundary of said formation is grounded and extends over a greater area than the ungrounded electrodes to shield the region above the grounded electrodes from leakage fields,
• applying electrical power at no more than a relatively low frequency between respective said rows of electrodes to substantially maximize the power delivered to said formation while producing relatively uniform heating thereof and thereby moderate the relative loss of heat to adjacent regions, and
• at the same time controlling the temperature of said electrodes below the vaporization point of water thereat to maintain an electrically conductive path between said electrodes and said formation.

A method for the in situ heating of an earth formation having substantial electrical conductivity, said method comprising:

• bounding a particular volume of said formation with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array wherein said electrodes are disposed parallel to and adjacent respective boundaries of said formation and the length and width of the active electrode area are large relative to the thickness of said formation to avoid heating barren layers,
• applying electrical power at no more than a relatively low frequency between respective said rows of electrodes to substantially maximize the power delivered to said formation while producing relatively uniform heating thereof and thereby moderate the relative loss of heat to adjacent regions, wherein power attenuation along the electrodes with the power applied at one end is no greater than 2 dB, and
• at the same time controlling the temperature of said electrodes below the vaporization point of water thereat to maintain an electrically conductive path between said electrodes and said formation.

A method for the in situ heating of an earth formation having substantial electrical conductivity, said method comprising:

• bounding a particular volume of said formation with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array wherein said electrodes are disposed parallel to and adjacent respective boundaries of said formation and the length and width of the active electrode area are large relative to the thickness of said formation to avoid heating barren layers,
• applying electrical power at no more than a relatively low frequency between respective said rows of electrodes to substantially maximize the power delivered to said formation while producing relatively uniform heating thereof and thereby moderate the relative loss of heat to adjacent regions, wherein power attenuation along the electrodes with the power applied substantially equally at both ends of the electrodes is less than 8 dB, and
• at the same time controlling the temperature of said electrodes below the vaporization point of water thereat to maintain an electrically conductive path between said electrodes and said formation.

A method for the in situ heating of an earth formation having substantial electrical conductivity, said method comprising:

• bounding a particular volume of said formation with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array wherein said electrodes are disposed parallel to and adjacent respective boundaries of said formation and the length and width of the active electrode area are large relative to the thickness of said formation to avoid heating barren layers,
• applying electrical power at no more than a relatively low frequency between respective said rows of electrodes to substantially maximize the power delivered to said formation while producing relatively uniform heating thereof and thereby moderate the relative loss of heat to adjacent regions, wherein the diameter of the electrodes are sufficiently large and the array of such electrodes is so dense that the I.sup.2 R losses in the electrodes are small relative to the power dissipated in the formation adjacent the electrodes, and
• at the same time controlling the temperature of said electrodes below the vaporization point of water thereat to maintain an electrically conductive path between said electrodes and said formation.

A method for the in situ heating of earth formations having substantial electrical conductivity, said method comprising

• bounding a particular volume of a said earth formation with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array wherein the active electrode area and the row separation are chosen in reference to the formation thickness to avoid heating barren layers, and
• applying electrical power at no more than a relatively low frequency for a limited period of time between respective said rows of electrodes to deliver power to said formation while producing relatively uniform heating thereof and limiting the relative loss of heat to adjacent regions to less than a predetermined amount,
• at least two adjacent said rows of electrodes being at the same potential and spaced from each other by a wall sufficiently thick to provide thermal capacity for cooling the formation in the vicinity of the respective electrodes during the application of power and sufficiently thin as to be heated to a desired temperature via thermal diffusion after the application of power has ended.