Fiber Optic Surveillance for Water and Polymer Conformance Monitoring in an EOR Project in Petroleum Development Oman

Abstract

Abstract The focus of this paper is to elaborate on the decisions taken based on the information obtained from the FO data in lab and field tests in polymer and water flood projects. It aims to provide insight into how Fiber Optic (FO) data through both Distributed Temperature Sensing (DTS) and Distributed Acoustic Sensing (DAS) can be used to quantify in-well injection conformance for both water and polymer. The data was analyzed collaboratively between Shell and PDO and used to build a robust workflow to generate an inflow profile for either the water or polymer phase. Also, it has been used to assess Out-of-Zone injection, matrix versus fracture injection, and to prove conformance & injectivity improvement after acid stimulation. The output from FO compares favorably with other reference data such as PLT. The paper will go through different aspects of workflow development covering all the methodologies used to convert FO data to inflow profile in flow rate. It will also provide information on how the obtained knowledge from this pilot can be replicated throughout various fields in and outside of Oman. The Fiber optic surveillance strategy for polymer flood has truly proven its value ready for potential upscaling for similar polymer projects. FO data was acquired from permanent fiber installed behind the 7″ production casing from water and polymer injectors in a field in the South of the Sultanate of Oman. A total of 14 DAS and 9 DTS surveys were acquired in 7 water injector wells followed by additional 4 DAS surveys in polymer injectors wells. DTS data were acquired during several injections and shut-in periods to measure the warm-back transient conditions before full stabilization to (pseudo) geothermal temperatures. Data were processed and analyzed using a thermal simulation model to allocate and quantify injection conformance per zone. DAS data were acquired during injection with a minimum of three flow rates. The data were processed, time-averaged, and filtered to specific frequency bands to identify injection conformance.