Evaluation of Geomechanical Parameters for Sand Prediction in Apogee Field Offshore, Niger Delta.

Abstract

The research focuses on the evaluation of geomechanical parameters for sand prediction in APOGEE, offshore Nigeria. Depletion of reservoir, increased water- cut, reservoir ageing, poor completion and poor reservoir management all causes sand production. Sand production increases the cost of maintenance of a well, leads to well shut in and jeopardizes the safety of worker. Four wells were evaluated using geomechanical parameters and well logs data (sonic log, Gamma ray, density, resistivity, and neutron log). Furthermore, six reservoirs were identified (reservoir 1- 6) and correlated across the five wells. Shear and compressive wave travel time from the sonic log were obtained and were used to estimate geomechanical parameters (both elastic and inelastic). The estimated geomehcanical parameters includes Poison ratio, Young modulus, Bulk modulus, UCS and pore pressure. Four methods were used to evaluate the sand potential and they include: B-index, Schlumberger index, Bulk modulus, Compression ratio and combined ratio. The analysis revealed a strong linear relationship between UCS and porosity with a regression coefficient correlation between 1 and 0. 98. This research shows the studied reservoirs falls below the threshold pressure for sand production. Comparing the four methods, the ratio of Shear modulus to the bulk compressibility ratio (G/Cb) method predicted the highest potential for sand production. This research therefore validates that reservoirs in APOGEE field is highly unconsolidated. Keywords: Poison ratio, Young modulus, Bulk modulus, UCS and Pore pressure and Sand control