as this frequency and voltage at least until the formation has reached a point where the electrical potential arcs from one electrode to at least one other electrode application_number US 201313852680 A description the present invention creates permeability in a formation by multiple mechanisms physical removal of rock mass by decomposition or vaporization of a portion of the rock by a plasma arc created by pulses of differential voltage between electrodes is one mechanism decomposition of rocks may be for example decomposition of dolomite or decomposition of calcite decomposition of dolomite can occur for example at a temperature of at least 530 u00b0 c leading to 21 loss of solid mass of dolomite according to the reaction decomposition of calcite may occur at about 900 to 1000 u00b0 c and leads to 44 loss of initial calcite mass for each pair of positions of electrodes rock will be removed in essentially a path between the positions of the electrodes because formations are not homogeneous the path of removal of rock will not be a straight line but along paths of least resistance between the electrodes in a coal or oil shale formation the presence of carbon will result in a first arc forming a more conductive path and further arcs tend to follow that path in formations that do not contain high contents of hydrocarbons such as tight gas formations the result is different the arcs tend to be transmitted along the surface of mineral solids when the arc causes such mineral solids to be removed rather than continuing to follow the similar path a different path will tend to become the path of least electrical resistance and therefore the electrical arcs will tend to remove rock mass along a line between.