Abstract: A layer stripping method that quickly and robustly determines values of undetermined parameters that model a formation (F). The layer stripping method includes applying inversion methods to subsets (d) of measured data (d) and corresponding modeled responses such that the value of a parameter determined during the application of an inversion method to one subset of the data (d) and the corresponding modeled response can be used to reduce the inversion space of a modeled response that corresponds to another subset of the data (d), to which an inversion method is subsequently applied.

Abstract: Method of analyzing a subterranean formation traversed by a wellbore. The method uses a tool comprising a transmitter antenna and a receiver antenna, the subterranean formation comprising one or more formation layers. The tool is suspended inside the wellbore, and one or more electromagnetic fields are induced in the formation. One or more time-dependent transient response signals are detected and analyzed. Electromagnetic anisotropy of at least one of the formation layers is detectable. Geosteering cues may be derived from the time-dependent transient response signals, for continued drilling of the well bore until a hydrocarbon reservoir is reached. The hydrocarbon may then be produced.

Abstract: Detecting in an earth formation a boundary between first and second formation regions having different resistivities, wherein the first formation region is traversed by a wellbore, using a logging tool provided with a number of electrodes including a monitoring electrode, the method having: a) selecting a location of the logging tool in the wellbore; b) assuming a position of the boundary relative to the selected location, selecting outside the wellbore a target point relative to the selected location, and selecting a target value for a selected parameter in the target point; c) assuming a model wherein the logging tool in the wellbore is surrounded by a homogeneous formation having the resistivity of the first formation region, and determining how two of the electrodes have to be energized in order that in the target point the selected parameter has the target value; d) selecting a monitoring parameter at the monitoring electrode; e) placing the logging tool at the selected location in the wellbore; f) de

Abstract: Detecting in an earth formation (51) a boundary (56) between first and second formation regions (54, 55) having different resistivities, wherein the first formation region (54) is traversed by a wellbore, using a logging tool (60) provided with a number of electrodes (61, 62, 63) including a monitoring electrode (63), the method comprising: a) selecting a location (65) of the logging tool (60) in the wellbore (57); b) assuming a position of the boundary (56) relative to the selected location (65), selecting outside the wellbore (57) a target point (67) relative to the selected location (65), and selecting a target value for a selected parameter in the target point (67); c) assuming a model wherein the logging tool (60) in the wellbore is surrounded by a homogeneous formation having the resistivity of the first formation region (54), and determining how two of the electrodes (61, 62, 63) have to be energized in order that in the target point (67) the selected parameter has the target value; d) selecting a moni