Abstract
Geosteering has relied on manual log interpretation for decades. This paper outlines a new, patent-pending method of automated geosteering dubbed Cybersteering. By utilizing a graph database spatially and assessing the quality of gamma matching for a large catalog of potential segments of constant bed dip (strat blocks), a geosteer can in many cases be constructed that closely mimics that of a manual steer. The Cybersteering proof of concept has the ability to lighten geosteering workloads while increasing productivity and accuracy of geosteers.
Introduction
Geosteering as a system and method for controlling a wellbore based on downhole geological measurements to stay within a pay zone originally rose to prominence in US onshore drilling in the late 1980s and early 1990s (Lesso, Jr.). Wells came to be steered with gamma ray once logging-while-drilling and measurement-while-drilling tools became more common, although steering based off of rate of penetration and mud samples was also common. Innovations since then have included the utilization of resistivity logs, various uses of seismic data, as well as experimentation with technologies such as mass spectrometry and x-ray diffraction (Durham). However, there has yet to be as large an advancement in geosteering as the initial move from the tedious analysis of paper logs to software that can display data graphically. Within such software, geosteerers can stretch or squeeze gamma ray log sections to match a total vertical depth (TVD) type log from a nearby well in order to correlate a well's stratigraphic depth. The general process requires a geosteerer to review gamma and trajectory data every time a survey comes in and visually determine the best overall gamma match between wellbore and type log through the manipulation of strat blocks, which are sections of constant bed dip. The gamma match is changed and determined by manually varying strat block length and angles (Stoner). A typical geosteering screenshot is shown in figure 1.
