Unconventional hydrocarbon reserves substantially surpass those of conventional resources and therefore are extremely economically attractive. However, exploration and production of unconventional reserves is challenging. This paper demonstrates that one can observe significant induced polarization effects in shale reservoir rocks, which can be used in exploration for unconventional reserves. The generalized effective-medium theory of induced polarization (GEMTIP) was used to model the complex resistivity of shale rocks. We demonstrate that GEMTIP modeling provides an evaluation of mineral composition and volume fractions in rock samples. We have conducted spectral induced polarization (IP) measurements using different types of shale rocks to test the feasibility of the IP method and GEMTIP modeling for studying unconventional hydrocarbon (HC) reservoir rocks.

Unconventional hydrocarbon (HC) reserves, e.g., heavy oils, bituminous sands, and oil-and gas-shale substantially surpass those of conventional resources and therefore are extremely economically attractive; however, exploration and production of unconventional reserves is challenging. This paper demonstrates that one can observe significant induced polarization (IP) effects in shale reservoir rocks, which can be used in exploration for unconventional reserves. This study is based on application of the generalized effective-medium theory of induced polarization (GEMTIP) for analysis of the complex resistivity (CR) of oil-and gas-shale rocks. GEMTIP modeling provides a basis for remote petrophysical analysis of shale rocks, which we compared with an actual structural analysis of shale rocks using Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) and core analysis. We demonstrate that GEMTIP modeling provides an evaluation of mineral composition and volume fractions in rock samples. Spectral induced polarization (SIP) measurements were conducted for different types of shale rocks to test the feasibility of the SIP method and GEMTIP modeling for studying unconventional HC reserves. The results of this study provide a basis for future application of the SIP method for exploration and monitoring of unconventional reserves.