Fiber-Optic Distributed-Temperature-Sensing Technology Used for Reservoir Monitoring in an Indonesia Steam Flood

Abstract

Summary The world's largest steamflood operation is conducted on the island of Sumatra in Indonesia. Fiber-optic distributed-temperaturesensing (DTS) surveys are used in the Sumatra fields to provide valuable data for reservoir management. The DTS profile data can determine the temperature and extent of a "steam chest," a phenomenon that occurs when steam injected into a steam-injection well moves away from the perforations until it encounters an impermeable barrier in the formation. The steam then extends laterally until breakthrough occurs at the producing well. Because oil is produced by gravity drainage, the steam chest (also known as a steam-saturated volume) grows downward. DTS surveys also have the capacity to determine the temperature gradient for either overburden or underburden reservoirs. This information is vital for properly setting steam-injection target rates. The information is also used to mitigate steam breakthroughs and eruptions, as well as to identify bypass oil. Steamflood operations experience many types of problems, including inefficient injection rates, wasted heat to the casing, sanding in producers, liner failures, and pump failures. There is also an ongoing need to improve the efficiencies of vapor collection systems, well-test stations, and central gathering stations. Based on these challenging problems, periodic wellbore temperature surveys are required to improve heat management and, ultimately, profitability. Conventional temperature logs cannot be run in these wells without first pulling the pumps from the completion. Therefore, a fiber-optic DTS system attached to the production tubing was suggested. This paper will present case histories of successful applications of fiber-optic DTS surveys that improved steamflood management in this steamflood field in Indonesia. The benefits from fiber-optic DTS monitoring were Significant improvement in the understanding of steam breakthrough zones along the pay-zone interval of production wells Improved understanding of the steam path in steam-injector wells Improvement of the real-time temperature profile in observation wells to identify steam-zone development and unswept or bypassed oil zones in the steamflood patterns