AAPG Middle East Region, Shale Gas Evolution Symposium

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The Role of Natural Fractures and Reservoir Stresses in Integrated Engineering Workflows – Constrained Frac Design and Fast Marching Reservoir Simulation for Optimal Development of Unconventional Reservoirs


Geophysical attributes could contribute significantly to improving the estimation of the distribution of natural fractures and reservoir stresses when used as input in engineering integrated workflows where other disciplines such as structural geology and continuum mechanics (instead of statistical methods usign very poor and biased statistics present in one or two wells) are used to estimate these key reservoir properties. Once these geologic realities are correctly estimated and validated with blind wells and predicted microseismicity they can then be trusted by engineers to be incorporated in their frac design and reservoir simulation tools. These concepts are first illustrated with the impact of regional faults on local stress rotation which requires horizontal wells to be drilled in varying directions adapted to the local stress rather the regional one. At the pad level, the role of natural fractures in creating heterogenous in magnitude and orientation stress fields which impact the final SRV is emphasized and illustrated with multiple Permian case studies.The optimal development of unconventionals requires that these geologic and geomechanical realities seamlessly make it in the engineering applications to better predict the frac geometry and the resulting EUR. New engineering tools that are able in few minutes (instead of days and weeks in current industry tools) incorporate both the complex geologic and geomechanical reality and match all the engineering data including pressure data during hydraulic fracturing and production data were developed to faciliate the true integration between 3G and engineering. To achieve such a high level of integration in the engineering workflows, new frac design tools and a fast marching reservoir simulator were developed to fully take advantage of the complex geologic reality very often ignored by engineers. Multiple case studies from Permian illustrate the reduction in engineering uncertainties when this very fast integrated workflow is used.