Advanced Drilling and Logging Technologies Give New Life to Aging Fields in Ecuador by Enabling Reentry Drilling

Abstract

Abstract Excellent results from a reentry campaign developed in 2014 in Ecuador have proven the benefits of implementing new drilling technologies for reentry drilling. In this campaign, rotary steerable systems (RSS) were drivers for directional control, and logging-while-drilling tools acquired critical information while drilling. Together these tools open up possibilities for giving new life to aging oil fields and to produce from unexploited drainage zones by enabling reentry drilling. Drilling the reentry wells in Ecuador involve using the 9.625-in. casing to open an 8.5-in. window and drilling to the geological objectives in just one hole section. For this purpose, the combination of a point-the-bit RSS system, a multi depth laterolog resistivity tool with high-resolution images, and a sourceless tool that delivers density, porosity, spectroscopy, and sigma provided 100% of directional control while acquiring comprehensive formation evaluation information in real time. Because of the casing configuration in most of the wells in Ecuador, the most commonly used reentry option is to make the window in the 9.625-in. casing and drill the 8.5-in. hole section from the Tena formation (claystone) and Napo formation (several intercalations of claystone, limestone, unstable shales, and pay zones of sandstone). This particular configuration of formation layers is a challenge for directional control and for running wireline logs. The use of the bottomhole assembly (BHA) with the RSS and tools described above enables successfully drilling the reentries in just one 8.5-in. run, reaching the geological targets with 100% directional control, in spite of the complexity of the well trajectory, and avoiding risks such as packoff, geometrical sticking, and differential sticking. The smoother well profile obtained by use of the point-the-bit RSS and verified through the LWD measurements guaranteed the successful run of the 7-in. liner in all of the reentries drilled in the campaign. Reentry wells provide operators with the opportunity to have new production at less than half the cost of a completely new well and in less than half of the total execution time. Building on this reentry campaign, continued reentry drilling will be improved with implementation of the new generation of hybrid RSS (push - and point-the-bit RSS), which will enable drilling engineers to plan trajectories to deliver greater dogleg severities (DLS). This will, in turn, enable developing deeper reentries, further reducing cost and execution time.