Closed-Loop Steerable Drilling Tools for High Temperature Application

Abstract

The drilling environment today calls for drillers to be able to access deeper, high temperature and high pressure reservoirs, where high temperature is defined as C and high pressure to 0.9 psi ft. Temperatures during geothermal applications can be well in excess of 200?C. A new family of automatic drilling tools has been introduced which provides automatic steering within ultra deep formations under high temperature and high pressure (HTHP) conditions. Another important use of this system is foreseen in the drilling of wells with extended reach horizontal sections. The directional changes in the Closed-Loop Drilling System are automatically generated on the basis of Measurement While Drilling (MWD) measurements taken directly within the tool. Since the major application aims at the very deep hydrocarbon layers, all components are designed to operate at temperatures between 185 to Special consideration is given to the design of downhole motor elastomer and electronic components of the MWD. In preparation for the field application of the complete fully directional tool, field tests have been performed with a Straight Hole Drilling Closed-Loop System and other essential system components. The Straight Hole Drilling Device has been designed to drill a straight vertical well. It has been successfully run on various onshore and offshore European locations; where in one case a maximum depth of over 7,200 m was attained. Additional field case histories are provided in this report on high temperature downhole motors. The complete fully directional system will be ready for field application within the first half of 1995.