Development of Expert System for Lost Circulation Problems

Abstract

Lost circulation (LC) is the phenomenon where circulating drilling fluid is lost to fracture or porous in the rock formation rather than returning to the surface. For drilling geothermal well, LC can be serious problem that contributes greatly to the cost of the average geothermal well and completion of the well. We studied "The research and development of lost circulation techniques in geothermal wells" to permit systematical lost circulation treatment undertaking committed by the New Energy and Industrial Technology Development Organization (NEDO) from 1986 to 1990, whose program consists of detection of LC analysis techniques, plugging materials, and treatment techniques. In this project, the expert system for lost circulation problems, so-called LC expert, was developed to support determination of LC treatment method for drilling engineers. The LC expert suggests drilling engineers to design the optimum LC treatment. We believe these suggestions would reduce uncertainty and mistake in decision process of field personnel. Developed LC expert designs the optimal solutions for LC treatment according to the information obtained from the LC detection tool and its data processing, knowledge base including experiences of drilling experts, properties of each plugging materials, knowledge obtained from simulation test, and knowledge from field test. It was evaluated by drilling experts and actual field tests that the LC expert inferred the LC treatment method quite adequately.