Horizontal Drilling in Kuwait for Development of a Complex Carbonate Reservoir

Abstract

Abstract Approximately 75% of the proven conventional oil reserves in the Middle East occur in carbonate reservoirs like Mauddud in North Kuwait. Today, this reservoir is the focus of aggressive development through drilling of horizontal wells. Mauddud in North Kuwait is heterogeneous with varying rock and fluid properties between crest and periphery. A major challenge in its development is the presence of high permeability streaks that are random, inconsistent and unpredictable. Though typical of carbonates this causes early breakthrough into producers and cycling of injection water into patterns resulting in poor sweep efficiency and oil recovery. The reservoir is under active water flood for over 10 years. Horizontal wells is not something new to KOC yet their objective, completion and integration with development plan is more holistic now than before. Mauddud today is at a point where its character, quality and condition favors development by horizontal and multi-lateral wells. The objective of drilling new horizontal wells is to have large contact area of the reservoir and the good news is that, despite early mixed results, we are beginning to see their positive impact. Modeling studies have indicated that a combination of pattern and peripheral water flood would help maintain reservoir pressure and achieve reasonable oil recovery. Encouraging production results from recent horizontal completions at the periphery of Mauddud structure, where rock quality is not good, is the beginning of a new phase of development in the life of this reservoir. The incremental production benefit is expected to be around 2-2.5 times the vertical. The paper discusses the typical design considerations, problems in drilling, lessons learnt, their benefit over offset vertical wells and test results of some of these wells drilled in Mauddud Reservoir.