Integrated Fault Seal Characterization for Reservoir Management

Abstract

Abstract Integration of pressure, production, geochemical, seismic, well log and structural data provides important information on the sealing capacity and dynamic behavior of fault-juxtaposed reservoirs. Reservoir juxtapositions and potential cross-fault communication pathways are easily defined with faultplane sections (Allan maps). Smear gouge ratios, calculated from E-logs, areused to estimate the composition of fault-gouge materials between thejuxtaposed reservoirs. History matching of the available production and pressure data with a full-field reservoir simulator are used to quantify the relationship between fault gouge composition and fault transmissibility. This paper presents the results of such a study conducted on the Meren field, Nigeria. The computed fault transmissibility was observed to correlate with the Smear gouge ratio (fault gouge composition). These tools are used to augment the interpretation of seal/nonseal character in proved reservoirs, assist in the quantification of fault-seal risk in untested fault-dependent closures and prove valuable in the management of reservoirs. Introduction Identifying the best practices for the development and management of ahydrocarbon reservoir involves integration of both the geology and reservoir engineering features of the field. The geological data could includeinformation on depositional environment, which can be used to gauge the arealextent of the field; structural geology, to identify the structural featuresincluding faults, their areal extent, amount of slip, and sand/sandjuxta position; and geochemical data that can be used to fingerprint the oil indifferent reservoirs and to identify possible communication, if any, existing between them either along or across a fault. Reservoir engineering and historical production data could be used to enhance the geologic interpretation and to assist in quantifying the effects of these geological features on the long-range production behavior of the reservoirs. In the present work the main purpose of the study was to analyze the behavior of faults from the standpoint of their conductance. Both geological interpretation and reservoir engineering analyses were used in this study of the Meren field, offshore Nigeria. The analysis involved a geological study of the faults using Allan maps to estimate the extent of the sand/sandjuxta position, Smear Gouge Analysis (SGA) to quantify the nature of the faultgouge, and Reservoir Simulation to estimate the transmissibilities of the faultgouge.