Rock Physics and Geo-Mechanical Analysis to Enhance Sanding Prediction in Oil Wells in “Chi Field” Offshore Niger Delta

Abstract

An integrated approach of rock physics and Geomechanical analyses was adopted in this study to enhance the prediction of sanding in oil wells within ‘CHI’ field offshore Niger Delta. The data used for this study include suite of wireline logs from three wells, base map and checkshot. concept of geomechanics was used in evaluating and understanding the rock mechanical properties of the reservoirs. Two reservoirs namely (RES1 and RES2) were mapped and interpreted. Elastic and geomechanical parameters were evaluated within the field, the parameters include; Poisson ratio, Young modulus, Bulk modulus, Shear modulus, and Unconfined compressive strength (UCS). The elastic properties of rocks are affected by geological factors which include: Lithology, Depth and Anisotropy. In addition, rock physics analysis was carried out using the friable, constant and contact cement model to quantitatively characterize the lithology and also investigate the degree of cementation, compaction trend and environment of deposition with emphasis on the reservoir. The geomechanical parameters reveal that the reservoirs within the study area is predominantly unconsolidated sandstone and friable shale which serves as reservoir seal. The result shows that the reservoir sand units have low Poisson ratio, Young modulus, Bulk modulus, Shear modulus and high UCS (0.31Gpa, 11.5GPa, 0.06GPa, 4.3GPa, 337.5psi respectively), with high compressibility value of 0.08GPa  at reservoirs intervals. This suggest that the reservoir rocks are brittle with high potential to tensile failure.