ERHA Development: Drilling and Completion Optimization

Olatunji Adeola and Chuck Duginski
Esso Exploration and Production Nigeria Ltd, Victoria Island, Lagos, Nigeria

This paper presents a case study covering drilling and completion design activities for development wells in the Erha field. Erha is a major subsea development in the emerging deepwater region offshore Nigeria. Drilling and completion considerations were a significant input to the design of the Erha field layout. Wellbore stability, directional drilling limits, drilled footage and completion issues were balanced against the cost of subsea equipment, and flow assurance issues. This multi-disciplinary approach has yielded notable efficiencies for both the development program and field operations.

The Erha reservoir consists of a sequence of multiple stacked channels. The depletion plan includes water and gas combination flood, as well as a limited amount of depletion drive. The complexity of the reservoir architecture and depletion plan gives rise to a variety of challenges to well design. Simplicity, flexibility and reliability have been stressed throughout the design process.

The paper focuses on evaluation of the conditions specific to Erha, desired functionality of the various well types, and the design optimization solutions that address these needs and conditions.