Development of Seals for a Geothermal Downhole Intensifier -- A Progress Report

Abstract

A system using high velocity fluid jets in conjunction with a rotary diamond bit is currently considered as the best candidate for reducing the cost of drilling geothermal wells. Technical, safety and cost considerations indicated that the required jet supply pressure can best be established by a downhole pressure intensifier. Key intensifier components are the check valve and plunger seals, which must prevent leakage of the high pressure, high temperature abrasive fluid (drilling mud). To achieve the required performance, novel ceramic seals are currently being developed. The check valve seal includes a tapered polymeric plug and ceramic stop acting against a ceramic seat. The ceramic plunger seal is a variant of the "stepped joint" piston ring and is designed to minimize contact pressure and abrasive wear. Initial testing of these seal in the laboratory shows encouraging result; design refinement and further testing is in progress.