Well Testing Operation and Analysis in the Subsea Horizontal Well In Offshore Bali - Indonesia

Abstract

SB gas field is located at a water depth of about 400 to 750 ft in the Kangean PSC area, +/- 120 km off North coast of Bali. Development drilling campaign was conducted in 2018 with target reservoir is Paciran carbonate. Follow Drill & Complete  philosophy, 3 Horizontal wells and 1 slanted well were drilled using floater – semisubmersible rig and completion phase were ran in 2 stages of Lower completion & upper completion. As part of the field development process well cleaning flow and flow after flow test had been successfully conducted after completion jobs to assist in evaluating reservoir characteristic.

There is one well namely well C whose trajectory is unique because the well must follow the actual geometry of the reservoir, so the trajectory is not perfectly straight at 90 degree. At the heel position penetrated +/- 400 ft. good permeability carbonate, after that +/- 300 ft. penetrated low to medium permeability and the remaining +/- 900 ft. penetrated good permeability carbonate.

This paper presents the testing design, data acquisition and analysis of well C. Testing design was conducted to meet the testing objectives and operation can be run smoothly. During well testing 3 gauges are used to measured pressure in surface, seabed and bottom hole. Well testing and data acquisition successfully performed with a good result. QA and QC had been done before the analysis; it shows all 3 gauges data are in a good agreement. Initially analytical model has been used to interpret the pressure transient data, however the model result of cannot fitted the derivative pressure in the early and late time period. It’s suspected due to response of different permeability of the carbonate reservoir affected pressure behavior. A numerical analysis with 3D simulation model was conducted to take into account the effect of well trajectory which penetrating multiple type of carbonate from the heel until the toe. A Local Grid Refinement (LGR) model is used to model reservoir behavior precisely. In addition well deliverability analysis was performed using flow after flow data.

The preparation including testing design and a good team work during operation is the key for this flawlessly well testing operation. The results of the analysis have helped us better understanding the reservoir characteristic and will be used to update current static and dynamic reservoir simulation model.