Application of an Integrated Approach for the Characterization of a Naturally Fractured Reservoir in the West Siberian Basement

Static modeling of naturally fractured reservoirs is a recurring challenge to many oil and gas companies seeking to manage and develop fractured reservoirs. Several techniques relying on curvature only or on one seismic attribute have been applied in the past to match past production and pressure history that have been proven unreliable. This paper describes the application of the Continuous Fracture Modeling (CFM) approach to improve the simulation of a fractured basement reservoir using seismically driven reservoir characterization. The Maloichskoe field is located in the southeastern part of the West Siberian basin in Novosibirsk oblast. It was the first field in the basin where commercial oil was produced from the Paleozoic basement. The reservoir consists mostly of limestones and dolomites that are intensively fractured and contain numerous vugs in some zones. The reservoir properties of the matrix are generally negligible, and the production potential of wells is mostly associated with natural fractures and vugs.<br>The presented study was our first project in Russia where a complete integrated approach was implemented to properly characterize a fractured reservoir. The approach included the following tasks: 1) Identification of fractured intervals in wells using a special technique of BKZ logs processing, 2) Spectral imaging and high-resolution inversion of the seismic data, 3) structural analysis of the field, 4) construction of the reservoir properties model, 5) construction of the fracture distribution model using the Continuous<br>Fracture Modeling approach (CFM). The final geologic model served as a basis to select the locations for the new wells. The new locations were proposed in the zones with the most intensive development of a network of natural fractures (according to the model). The drilling was associated with significant losses of drilling mud that was an indirect indication of presence of significantly fractured zones. The wellbore image FMS that was recorded in the well, showed a good level of correspondence between the model forecast and the actual result. The well contains interval of numerous fractures and large vugs. Eventually, the well showed a good production results and currently is one of the best producers in the field. As such, we recommend application of the described integrated approach for modeling complex fractured reservoirs in the other fields of Russian Federation.