Improving Workover Success Ratio Through Integrated Subsurface Evaluation: Bunyu Field Cased Study
Keywords:
Integrated Evaluation, Workover success ratio, SEE (Selection, Elimination, Execution)Abstract
Bunyu Field is one of the backbones of Pertamina EP production in Asset 5 region with reservoir characteristics deposited in a deltaic environment. The rate of natural decline of 70 percent production per layer becomes a major challenge in maintaining and increasing production in this field.
To address these challenges, one of the Bunyu field production improvement strategies was carried out with a revolution in the selection of workover candidates and well intervention that was originally done in an integrated manner. Through this integrated method, candidates have gone through a comprehensive evaluation process from well candidate selection, target layer elimination, to perforation execution from both geological, reservoir and production aspects. The comprehensive evaluation includes mudlog data analysis and gas ratio, open hole log, petrophysics, structural correlation and stratigraphy, cement bond evaluation, formation pressure, downhole sampling, until the latest saturation log.
The application of the method successfully increased the success ratio of the workover work with the achievement of 106.1% of the target. This achievement helped to increase Bunyu Field production significantly from 2500 bopd in mid-2017 to 4000 bopd by early 2018.
