An Integrated Approach to Phase-Wise Marginal Fields Cluster Development – A Case Study of C Series Offshore Fields, India

The C-Series fields are mainly gas bearing with marginal reserves distributed in multiple pays and spread over a large area. They are located in the Arabian Sea, far away from existing infrastructure, in shallow water depth (24-30m), having very high under currents and adverse weather conditions. As independent development was not viable, concerted efforts involving integration of human resources, advanced technologies improving scale of economies by cluster development and changed economic scenario, these fields could be made economically feasible. The paper brings out how development has been undertaken using new concept and technologies in a phased manner to reduce capital cost of platforms, pipeline & processing facilities to maintain plateau rate for a few years. This paper discusses multidisciplinary task based parallel working with real time integration of results and midcourse corrections while formulating fast track phased development plan. The functional tasks included geological modeling, reservoir simulation, innovative well drilling and well design, assessment and adequacy of existing and nearby facilities and pipelines to minimize offshore development cost, simulation of fluid flow dynamics for both wells and pipelines for various operating conditions, well design & drilling options, well completion, selection of material, equipments and facilities. Besides setbacks in some fields, substantial upward revision of gas in place has been established in other area and it has been decided to advance the later phase development for early monetization of upside reserve using an old rig to be converted as MOPU for phase segregation and compression. This paper also discusses brief details of the selected options while presenting this classic case of this challenging offshore cluster development.