Slim Hole Reservoir Characterization for Risk Reduction

Abstract

High initial capital requirements and subsurface risk are commonly cited as significant impediments to more widespread development of hydrothermal resources. However, expensive production wells are often drilled at the early stages of development when risk is high. By drilling and testing slim holes at early stages, a developer can realize a significant reduction in risk at reasonable cost. In this paper, we will review different drilling approaches, their costs and impact on risk reduction. Slim holes have been promoted for reservoir characterization because of lower cost. However, they are also conducive to enhanced data collection that is critical for establishing conceptual models. Properly conducted injection tests provide reservoir engineering information that is equivalent to data collected from large well tests. When utilized in the reservoir testing phase, slim holes can provide greater volumetric sampling of a prospect than production-size wells at an equivalent cost. Therefore, significant risk reduction can be realized before the initiation of high-cost field development. Exploration is a knowledge-based activity and data collection and application to conceptual reservoir models is a requirement. We briefly discuss the data framework of the Play Fairway approach to demonstrate risk reduction.