6 July 2000 Two-dimensional conductivity image from the data measured by electromagnetic crosswell tools
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Abstract
The predicting and monitoring of fluid movement during a steam-injection operation is much important in an EOR process. A crosswell 2D conductivity imaging technique is developed to monitor the injection or production profiles by inverting formation conductivity from crosswell electromagnetic measurements. The tool responses are calculated from electromagnetic field equations using perturbation approach. Maximum entropy constraint is used to regularize the inversion problem. To assure the stability and fast convergence, the inversion procedure is conducted in three steps: homogeneous inversion that assumes the formation with an unique conductivity; 1D inversion that generates horizontally layered formation; and 2D inversion that regards the conductivity anomalies both in vertical and radial directions. An initial guessed value of homogeneous background is needed for the program at the beginning. The calculated result of homogeneous medium is then used as the initial value of 1D inversion, and the reconstructed layered conductivity profiles are the initial input for the 2D inversion. By the steps from homogeneous to heterogeneous inversion, the misfit between measured and calculated data decreases sharply. The examples for both synthetic data and field data are illustrated. The inversion results show that the reconstructed conductivity images are in agreement with the known formation characters within given error tolerances.
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Jianhua Zhang, C. Richard Liu, "Two-dimensional conductivity image from the data measured by electromagnetic crosswell tools", Proc. SPIE 4129, Subsurface Sensing Technologies and Applications II, (6 July 2000); doi: 10.1117/12.390615; https://doi.org/10.1117/12.390615
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