Patent ID: 7209834

Claim:
A method for estimating distance between a borehole and a subterranean geophysical boundary within a geophysical region, comprising: defining a resistivity model of the resistivity characteristics of said geophysical region based on available resistivity data for said region; defining a hypothetical borehole having a trajectory extending through said geophysical region, said hypothetical borehole trajectory at a plurality of discrete locations along the length of the borehole being spaced apart from said geophysical boundary by a plurality of selected distances; deriving from said resistivity model a plurality of hypothetical resistivity sensor values each corresponding to one of said plurality of discrete locations along said hypothetical borehole; deriving an equation approximating a mathematical relationship between said plurality of resisitivity sensor values and said plurality of selected distances; wherein said equation defines a relationship between actual resistivity sensor data and quantified estimates of distance between an actual borehole and said geophysical boundary.