Workflow to Image Unconformities with Deep Electromagnetic LWD Measurements Enables Well Placement in Complex Scenarios

Abstract

Abstract The advent of deep-reading directional electromagnetic logging-while-drilling measurements brings opportunities in imaging complex formations around the wellbore. In this context, basing the inversions on an assumption of a layered medium is not always sufficient to decouple geometrical effects in complex formation scenarios. Rather than attempting to invert all variables of a generic 2D formation model simultaneously, we describe in this paper how the use of 2D inversions can be enabled through a robust workflow specifically designed for a class of formation models, in this case the angular unconformity. We demonstrate how the successive application of 1D inversion to subsets of tool data gradually builds a formation model for use as input to a 2D inversion, which accounts for complex couplings present in the data in such environments. The validity and the performance of the method are established through synthetic and field datasets.