Geosteering Optimization Using the Multi-Boundary Detection Technology in Rubiales' Field, Colombia

Abstract

Horizontal drilling is part of the development plan for Rubiales field in Colombia, operated by the National Oil Company. By this, different geosteering technologies have been applied during the infill drilling campaign and, it has varied over time. The multi-boundary detection tool has successful results in terms of net sand percent increase, precise location, and cost decrease, related to drilling operations. Some of the challenges for well placement are thin thickness channels with no lateral continuity (deposition environment), oil-water contact closeness, poor correlation with cutting samples, between others. The technology minimizes risks with the real-time resistivity inversion. This process generates a visual representation of the resistivity profile around the wellbore, including geometric definition, dip, and thickness estimation. These inversion results are used to recommend trajectory adjustments while drilling. The complete geosteering experience in Rubiales with the new technology (more than one hundred sixty producing wells so far) has been classified into three main types of wells: lateral sections drilled in continuous sand intervals; lateral variation of resistivity; and wells with a change of prospective zone by channel discontinuity. The implementation success is described by the net sand percentage increasing, around 16% compared with other technologies. The average drilling length was improved by 20% and the number of geological sidetracks concerning previous stages of exploitation reduced by more than 90%, without affecting the drilling rate. These factors, including the update of the sedimentological models, inclusion of new reserves, and the production increase, are part of the optimization plan.