Non-destructive electromagnetic sensing methods play an important role in upstream energy industry applications. They enable acquisition of a wealth of information on rock and fluid properties, provide means for communication, and also provide pipe localization and integrity information. Use of electromagnetic measurements in the energy industry span a wide range of frequencies, physical regimes and methodologies for sensing and inversion. Particular examples are: quasi-magnetic problems in the range of 0.1 – 100 Hz such as ranging or pipe integrity assessments; quasi-electric problems in the range of 1 – 50 kHz such as galvanic (Ohmic) sensing; and electromagnetic problems in the range of 10 kHz – 1 GHz such as induction and dielectric measurements. This wide variety of physical regimes poses a challenging problem in modeling and inversion, where a combination of methods, such as finite-element, finite-difference, integral equations, method of moments, semi-analytical formulations need to be utilized in various coordinate systems. On the inverse problem side, while some problems allow linearization and interpretation through analytical relationships, others require a solution of ill-posed non-linear equations through iterative techniques.
The goal of the seminar is to (i) give an overview of upstream operations in the oil industry and their relationship to EM sensing; (ii) provide a review of the major EM sensing techniques (galvanic measurements, induction, dielectric measurements, eddy current for pipe inspection, and ranging): physical principles, modeling and interpretation challenges.