Reservoir Monitoring, Well Diagnostic, and Stimulation Job Evaluation using Permanent Fiber Optics Distributed Temperature Sensing DTS in a Mature Field

Abstract

Abstract As part of the reservoir monitoring effort in Field X (Offshore East Malaysia), five oil producers were deployed with double-ended fiber optics cable across reservoir sections and permanent downhole gauges (PDG). Each well has between 2 to 4 zones. This has enabled various distributed temperature sensing (DTS) benefits such as gas-lift monitoring, well integrity, zonal-inflow profiling, and stimulation job evaluation, etc. This paper demonstrates and discusses the approach of incorporating both DTS & PDG data in Well B-1 to intrepret temperature signatures andanomalies during recent tubing-integrity tests, matrix acidizing and post-job production performance. Well B-1 is a gas lifted well that consists of three zones, and its production has been declining over years due to potential formation damage during drilling and fines migration issue. Hence, Well B-1 has been selected for matrix acidizing treatment to enhance the productivity. Prior to execution of the acidizing job, several conformance jobs such as tubing-integrity tests, injectivity test, and tubing pickling were performed. A baseline temperature was acquired to assist in the evaluation. Due to operational challenges, the DTS data transmission wasn't acquired in real-time. However, each event's temperature profile has been studied thoroughly against the actual event schedule. Some significant findings are i) completion accessories effect (feedthrough packers) creates temperature anomalies, and ii) several leak points detected mainly between two upper zones where there was significant cooling effect due to injected fluid. The first-stage main treatment was conducted focusing on Zone 3. Due to leak points between the two upper zones, Zone 3 didn't get the designated main treatment volume. Second-stage main treatment, Zone 1 & 2 were treated together due to time constraint unlike Zone 3. Post job production temperature profiles showed significant changes in the flowing temperature slope compared to pre-treament profile where there is an increase in overall wellbore temperature indicating increase in liquid volume and Zone 2 indicating higher Joule-Thompson cooling effect (more gas production).