Abstract

After 26 years of cold production in a South of Oman heavy oil field, enhanced oil recovery through steam-flooding is currently planned. The first steam-injection pattern started in 2009 and the challenge is to monitor the rate of growth and shape of the steam chest at 1,000 m below surface. The Well and Reservoir Management (WRM) plan for this field includes a comprehensive set of areal surveillance activities including seismic and non-seismic methods that have been put together by a joint effort between Petroleum Development Oman (PDO) and Shell International EP (SIEP).

The approach to monitoring the steam conformance and sweep efficiency as the steam is injected in the reservoir focuses on simultaneously deploying a wide range of proven technologies early on. The objective is to select the most appropriate tool for the later full field deployment. The first active pattern is currently being used to investigate the effectiveness of existing seismic techniques such as cross-well and 3D vertical seismic profiling (VSP) to detect early signs of steam front movement. Pre-steam baseline data has been acquired and forward modeling helped determine the best time for repeat surveys. The more traditional, though challenging in South Oman, surface seismic data is also being adapted to the crowded conditions of the field. Alternative plans also include state-of-the-art high resolution virtual source seismic as well as surface deformation and time-lapse geochemistry. Improved lateral and vertical resolution at depth are key factors for success in this and future similar developments. Details of the areal surveillance programme and initial results are summarized here.

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