MEMS-based Downhole Inertial Navigation Systems for Directional Drilling Applications

Abstract

Conventional methods in horizontal drilling processes incorporate magnetic surveying techniques for determining the position and the attitude of the bottomhole assembly. Magnetic surveying results in higher costs and relatively large surveying errors. Micro-Electromechanical Systems (MEMS)-based inertial navigation has been proposed as an alternative to magnetometer-based downhole surveying due to its light weight, small size and low power consumption. The present study explores the feasibility of utilizing MEMS-based inertial measurement unit as a surveying sensor, in conjunction with a Rotary In-Drilling Alignment (R-IDA) method for measurement-while-drilling (MWD) processes. A novel, downhole-mountable, autonomous and cost-effective apparatus to practically implement R-IDA has been proposed and its capabilities to reduce the azimuth error have been assessed. Furthermore, this study discusses the concept of wireless data transmission within drill pipes downhole. It is shown that wireless telemetry inside the drill pipe is potentially capable of transmitting at a relatively high rate with low power consumption.