We propose a new iterative method for post processing through casing resistivity (TCR) measurements. This method can be seen as a correction or extension of Kaufman´s theory to more complex scenarios, in which the casing is no longer assumed to be uniform along the axis of the borehole. It can also be seen as a simplified inversion method based on the main physic al principles of TCR measurements. To derive our post processing method, we first use the method of images, which enable us to introduce all key factors involved on TCR measurements, including casing length, casing radius, casing thickness, formation resistivity, location of injected current and resistivity distribution of formation layers . Then, we design our iterative Post processing Method by simplifying the complex formulation resulting from using the method of images. Numerical results using goal oriented hp FEM simulations show that our correction method provides a more accurate approximation to the actual formation resistivity than that predicted by Kaufman´s theory. In addition, the new method is pr oven to be very efficient and robust, since it is independent of spatial resistivity variations in the formation.

MTM2010 16511