Demonstration of thermal borehole enlargement to facilitate controlled reservoir engineering for deep geothermal, oil or gas systems

Michael A. Kant, Edoardo Rossi, Jonas Duss, Florian Amann, Martin O. Saar and Philipp Rudolf von Rohr

Applied Energy, 2018, vol. 212, issue C, 1509 pages

Abstract: The creation of deep reservoirs for geothermal energy or oil and gas extraction is impeded by insufficient stimulation. Direction and extension of the created fractures are complex to control and, therefore, large stimulated and interconnected fracture networks are difficult to create. This lack of control and efficiency poses an inherent risk of uneconomic reservoirs, due to insufficient heat-sweep surfaces or hydraulic shortcuts. Therefore, we present a technique, which locally increases the cross section of a borehole by applying a thermal spallation process to the sidewalls of the borehole. By controlled and local enlargement of the well bore diameter, initial fracture sources are created, potentially reducing the injection pressure during hydraulic stimulation, initiating fracture growth, optimizing fracture propagation and increasing the number of accessible preexisting fractures. Consequently, local thermal borehole enlargement reduces project failure risks by providing better control on subsequent stimulation processes. In order to demonstrate the applicability of the suggested technique, we conducted a shallow field test in an underground rock laboratory. Two types of borehole enlargements were created in a 14.5 m deep borehole, indicating the feasibility of the technology to improve the productivity of geothermal, oil and gas reservoirs.

Keywords: Enhanced geothermal systems; Unconventional oil and gas; Reservoir engineering; Hydraulic stimulation/fracturing; Thermal spallation drilling; Bore hole enlargement (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (7)

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DOI: 10.1016/j.apenergy.2018.01.009

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