Phased Field Development and Early Performance: Challenges, Strategies, Observations and Learnings; Deepwater Nigeria

Nonny C. Nwogbo, Godwin A. Uboh, Edwin U. Nwaeri, Anthony Duruewuru, Ugo Oguamanam, Richard Lovell, and Allan Coulton
Deepwater, Esso Exploration and Production Ltd, Lagos, Nigeria

The subject field is one of ExxonMobil’s fast track developments in deepwater Nigeria. The field is developed as a satellite tie-back to the main field FPSO. First oil was in 2006, three years after field discovery. Current production is 45 Kbd from 5 producers supported by 4 water injectors.

The field consists of three upper Miocene, major laterally offset, SW-NE trending channel complex sets (CCS) bounded by erosional surfaces. Potential reservoir connectivity issues can be attributed to mud drapes on channel bases and NW-SE striking normal faults.

A phased development plan was adopted due to the potential compartmentalization issues and poor seismic imaging of the southern part of the field. Phase 1 targeted the better imaged Northern and Central CCSs (40% of total field area). Phase 1 Expansion focused on the Southern CCS and relied on the high resolution seismic acquired in 2005.
Initial development wells, early production and dynamic data were used to address uncertainty in fluid contacts and reservoir presence and connectivity. Interference tests were designed at field start-up to address the multiple stratigraphic and cross-fault connectivity scenarios. Several geologic models and reservoir simulations were constructed to facilitate development well planning.

Phase 1 and Expansion well results are in line with pre-drill predictions. Well interference and dynamic tests indicate that connectivity within and across channels can be highly variable within relatively low net deepwater CCSs. Sealing and baffling faults were also identified.

As part of the overall field development, a new round of geologic modeling and simulation efforts incorporating well and performance results is underway to optimize Phase 2 development. Integration of 4D seismic (2008) with production history will also identify infill drill opportunities to improve sweep efficiency.

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