An Integrated Approach for Evaluating and Characterising Horizontal Well Inflow and Productivity in Heterogeneous Carbonate Reservoirs

摘要

Carbonate reservoirs are generally highly heterogeneous and complex because many phenomena, such as diagenesis and tectonism have modified primary depositional structure and texture. Many carbonate reservoirs in the Shuaiba Formation of north Oman are characteristically heterogeneous with complex reservoir architecture. It is common to observe dualmedia and natural fracture system behaviors with large variations in reservoir properties. Many of these reservoirs have been developed with horizontal wells, so they require application of advanced reservoir evaluation and management practices. Many of the horizontal wells produce at high water cuts, despite apparent initial high oil saturations. The need for data is paramount for effective management of these reservoirs, and to understand factors affecting the productivity of horizontal wells - both at the wellbore and within the reservoir itself. The first stage of this process is to define an accurate structural model incorporating all available reservoir, wellbore (2D modeling) and seismic data. The second stage, involves integrating this model with the inflow profile derived from advanced production logging measurements. We describe several field examples from a complex and heterogeneous carbonate reservoir in Oman, and discuss how they may be used to identify a range of important needs relating to horizontal well placement, improving completion strategy, and optimizing water shut-off activities.