Abstract

Hydraulic fracturing has been the principal production enhancement technique in low-permeability reservoirs for the past few decades. Through core and outcrop studies, advanced logging tools, microseismic mapping and well testing analysis, the complexity of induced fracture network in the presence of natural fractures has been further elucidated. Although most natural fractures are cemented by precipitations due to diagenesis, they can be reactivated during fracturing treatments and serve as preferential paths for fracture growth and fluid flow. However, current technologies for posttreatment fracture analysis are incapable of accurately determining the induced fracture geometry or estimating the distribution of preexisting natural fractures. Despite significant advances in the numerical modeling of fractured reservoirs, those numerical models require detailed characterization of natural fractures, which is essentially impossible to obtain. Moreover, most modeling techniques could not incorporate posttreatment data to reflect actual reservoir characteristics. We have developed an integrated modeling workflow to estimate the actual characteristics of fracture populations based on formation evaluations, microseismic data, treatment data, and production history. A least-squares modeling approach is first used to define possible realizations of natural fractures from selected double-couple microseismic events. Forward modeling incorporating a discrete fracture network will subsequently be used for matching treatment data and screening generated fracture realizations. Reservoir simulation tools will also be used thereafter to match the production data to further evaluate the fitness of natural fracture realizations. Our workflow is able to integrate data from multiple aspects of the reservoir development process, and the results from this workflow will provide geologist and reservoir engineers a robust tool for modeling naturally fractured reservoirs.

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