1.1 Acre Thermal EOR Pilot & Field Testing Best Practices, Sultanate of Oman

Abstract

The A West heavy oil reservoir in the South of Sultanate of Oman is a very attractive target for thermal EOR considering its low primary oil recovery of 20%. The field development plan proposed Vertical Steam Drive as a development concept for Phase 1 that included drilling and operating a total of 80 3.3 Acre inverted 7 spots patterns. Vertical and areal steam conformance has been highlighted as one of the main challenges in one of the most complex and thick heavy oil reservoirs in the world. As a result, the plan has proposed executing and operating a smaller spacing 1.1 acre pattern in parallel with full field development of the 3.3 acre patterns. The main objective of the trial is to run a full lifecycle in situ steam flood in 2-3 years compared to 15 – 20 years at field scale spacing. This will accelerate learning on steam breakthrough management in combination with understanding how to improve vertical and areal sweep conformance. A fully integrated surveillance plan using advanced technologies including down hole DTS temperature fiber cable, covering the whole wellbore have been installed in all producers. In addition to that real-time wellhead temperature monitoring is a key surveillance element to sense the impact of steam break-through in the producers. Multi-tracers injection will also be executed to monitor the areal sweep efficiency and estimate the preferential movement of the steam within the subsurface by measuring the concentration of the tracer in the producers. Along with that, mechanical conformance applications have been installed in the steam injectors to add an additional control on vertical steam conformance and test the effectiveness of such application on addressing steam break-through issues. The trial will provide direct experience in managing steam injection and production after steam breakthrough that can later be implemented on a larger scale. The integrated data from the trial will aid in calibrating the simulation models to anticipate the time to steam breakthrough and build confidence in the power of the model for short/long term forecasting. In addition, it will also provide early indications of the effectiveness of some of the new technologies and surveillance in predicting and addressing steam conformance challenges and hence optimize the steam flood process.