The Role of Welltesting in Improving the Productivity from a Thin, Tight, Fractured and The Role of Well Testing in Improving the Productivity From a Thin, Tight, Fractured and Compartmentalized Limestone Reservoir

摘要

This paper describes a creative and pragmatic approach that improved the production from one of the most difficult reservoirs in the Bahrain field. The Middle Cretaceous Ab zone is a thin, tight, highly faulted, and irregularly-fractured limestone reservoir. The difficulty with this 15 ft, 1 md reservoir has prevented an efficient recovery. The average production of wells is 15 bopd. This has prompted a detailed integrated study plan to increase the wells' productivity. Welltesting was key to understand the reservoir dynamics. A comprehensive welltesting campaign revealed a flow mechanism controlled by a fracture network. Fracture modeling and simulation failed to give clues on how to improve the productivity. However, the new approach that links transient welltesting and production data with fracture network indications derived from seismic interpretations has resulted in improving the productivity considerably. This was accomplished through re-entering old wells and designing special trajectories to intersect productive open fractures. The productivity was significantly increased to 60 bopd with sustained performance. The paper describes in detail our approach and methodology to understand the reservoir and its drive mechanism and to increase productivity and recovery starting from analyzing core data up to designing special configuration wells. The paper further highlights the pitfalls of the conventional workflow approach in modeling such difficult reservoirs.