A Novel Workflow for Predicting Seismic Reservoir Characterizations - OBN Case Study - Western Offshore, India

Abstract

Objectives & Scope To identify the extend and improve the hydrocarbon productivity of the reservoirs in the area, seismic inversion study was carried out with the latest seismic image data to characterize the lithology and identify the potential reservoir distribution in the area. Advantage of OBN multi-component seismic data is the capability of providing PP & PS datasets as it helped to conduct PP-PS joint inversion enhancing the inverted shear impedance and density followed by seismic stochastic inversion for better vertical resolution. Challenges & Procedures Challenge #1: The presence of un-delineated karst features within H3B reservoir unit causing lots of water break through, mud loss while drilling and losing the control on the newly drilling wells. Challenge #2: To locate new save optimized candidates for infill wells securing the production plateau and minimizing the risks behind the reservoir facies/quality. To meet the objectives a seismic reservoir characterization study was carried out by conditioning seismic dataset followed by angle stack generation of PP & PS datasets. Seismic velocity from imaging product was used to trend the low frequency model building after calibration with the well logs. All the information was then used to conduct pre-stack PP-PS joint inversion to generate several attributes such as P-Impedance, S-Impedance, VpVs ratio, density. This was followed by seismic stochastics inversion to enhance the vertical resolution beyond the seismic band-limit and to reduce the uncertainties, P10, P50 & P90 cases of elastic/Petro-elastic properties have been provided. Also, a full seismic attribute analysis has been performed to help locate the potential sweet spots for better well optimization processes. In addition to that the petro-elastic attributes have been used to trend the rock-models and compensate for the environmental model in 3D mode away from the well locations.