The Principles and Procedures of Geosteering

Abstract The management of directionally drilled wells has recently progressed to the stage where targets have been reduced in size to a point in the earth with no tolerances. These targets can and are changed during the drilling process. The management of these point moving targets, usually in high angle or horizontal wells, is a precise form of directional drilling now called geosteering. It is this precise placement of the wellbore that creates the value in drilling these wells. Several technologies have made this advancement possible. These include reliable steerable systems, improved and new physical formation measurements, log data modeling, sensors near the bit and instrumented motors, and detailed reservoir mapping with the help of 3D seismic processing. Most papers on geosteering have concentrated on one of these advances. This paper addresses how these technologies are merged to execute the successful geosteering project. New systems, sensors, and computations have created a mass of data and control parameters that require real-time decisions bv operator personnel based on technical recommendations from service companies. These decisions have a critical impact on the net worth of a project. The team involved must rely on each other's expertise and understand the overall objective of a geosteering project. To do this, it is paramount that data from these different technological areas be merged into a 3D visualization encompassing geological structures and drilling trajectories. Patterns in procedures have developed from these projects over the past three years which demonstrate the difference between a successful project and a failure. The examples in this paper illustrate the techniques that will enable a change in the outlook towards precision directional drilling and completion projects.