Frequent 4D monitoring with DAS 3D VSP in deep water to reveal injected water-sweep dynamics

Abstract

Time-lapse monitoring using 3D distributed acoustic sensing vertical seismic profiles (DAS VSPs) is rapidly maturing as a nonintrusive low-cost solution for target-oriented monitoring in deep water. In a Gulf of Mexico field, DAS fibers deployed in active wells enable detailed tracking of the water flood in two deep reservoirs. Multiple tests in adverse well conditions let us understand the impact of source size and other factors on the spatially dependent quality of time-lapse DAS data and prove that excellent image repeatability is achievable under typical field conditions. Frequent repeat surveys allowed us to predict the timing of water arrival in a producer and to observe new water injection patterns that are important for understanding water-flood performance. Going forward, DAS 4D monitoring is envisioned as a tool that can assist with proactive wells and reservoir management, new well planning, and reservoir model updates.