Measuring and Profiling Water Ingress in an Emulsion Flow with a Compact Array Production Logging Tool and Successfully Shutting Off Water

Abstract

Water-in-oil emulsion represents a substantial volume of the produced water while the process of demulsification at surface remains costly. Accurately determining the source of water in oil producers with emulsion flow remains a challenge for production logging (PL). This paper presents a case study that shows how an innovative PL suite meets the main objectives of delivering a robust and accurate diagnostic of water ingresses and of informing an operational decision of a water shut off in an open hole gravel completion. After a history of deploying legacy centralized PL strings with sub-optimal probe and measurement capabilities in emulsion flow regimes, an operating company elected to deploy a third generation Production Logging Tool (PLT) which ultracompact length of 1m results from use of microelectromechanical systems (MEMS). The PL platform combines centralized measurements of pressure, temperature, Doppler, MML (CCL) with oriented azimuthal array holdups and flow speed sensors. The holdup measurements consisted of proven triphasic optical probes and conductivity probes and of newly developed micro-capacitances designed to sense micrometer water droplets in oil continuous phase. The PL survey was acquired on memory and deployed on slickline during well shut-in and at three different flowing rates. Very consistent and reliable gas holdup was measured by the triphasic optical probes through the whole acquisition. The water holdup was calculated using the micro-capacitance data as it proved to be the most accurate, in particular during the highest rate. The optical water holdup agreed well with the capacitance at intermediate and lower rates. The electrical probes were affected by water emulsion flow and stopped detecting water at flow speeds larger than 200 fpm (feet per minute). Excellent flow speed measurements were obtained with the robust micro-spinners covering a wide range of flow speeds from a few fpm up to 500 fpm. The main source of water was located at the bottom of the gravel pack completion. The PLT was run with an innovative combination of flow speeds and holdups sensors that allowed to reliably diagnose the water ingresses. Based on these results, a water shutoff intervention job was decided, implemented and coupled with a gas lift valve change to improve the gas lift injection that eventually led to a significant increase in oil production close to 1000 bbl/day and 10-point reduction in water cut. The extremely compact PLT with collocated holdup and flow speed sensors enable to deploy array production logging with limited rig up height. State of the art methods for measuring water holdups such as resistivity or conductivity fail in these extreme conditions due to the extremely small size of water droplets. The newly developed micro-capacitances are designed to sense micrometer water droplets in oil continuous phase, which is typically of emulsion flow.