4D quantitative interpretation of Jubarte field (Brazil): an integrated approach

Abstract

The use of time-lapse (4D) seismic data and quantitative interpretation is essential in the characterization and monitoring of oil reservoirs. This information reduces reservoir management risk, allows better well designs and placement, and improves history-matching. This work studies the application of 4D quantitative interpretation on the post-salt reservoir of the Jubarte field, a Brazilian deep-water oil field. In this project, I face the challenge of conducting a 4D study using seismic acquisitions only one year apart, which is a short interval to observe significant time-lapse changes. However, a high repeat permanent reservoir monitoring system (PRM) helps detect small time-lapse signals. Conventionally, 4D interpretation is conducted with only PP-wave reflection data. In this thesis, I use 4D PS-wave reflection data as well. I present a novel integrated interpretation of joint PP-PS elastic inversion, as well as PP and PS time-shift volumes. Further, I build a rock physics model from well and core data. A detailed comparative analysis of PP and joint PP-PS inversion shows that the joint inversion results are superior in terms of noise content and spatial continuity. Also, the 4D PP-PS joint inversion estimates show a better match with the rock physics models, allowing for more reliable interpretation. 4D time-shifts are integrated with 4D inversion results to discriminate between pore pressure and fluid saturation changes. I observe that time-shifts and inversion estimates provide information on reservoir properties at different scales. The integrated interpretation of the different 4D seismic attributes brings a much broader view since it uses independent data with complementary information to differentiate the effects of saturation and pore pressure changes as the field produces. The information generated in this project can be used to update Jubarte's flow simulator, for placing new injection and producers wells (which can bring significant savings, considering the high cost of drilling offshore wells), in addition to the improved production.