SPE Journal
Volume 18, Number 2, April 2013, pp. 345-354

Summary

We developed an injection strategy to recover moderately heavy oil and store carbon dioxide (CO₂) simultaneously. Our compositional simulations are founded on pressure/volume/temperature-(PVT-) matched properties of oil found in an unconsolidated deltaic sandstone deposit in the Gulf of Paria, offshore Trinidad. In this region, oil density ranges between 940 and 1010 kg/m³ (9 to 18°API). We use countercurrent injection of gas and water to improve reservoir sweep and trap CO₂ simultaneously; water is injected in the upper portion of the reservoir, and gas is injected in the lower portion. The two water-injection rates investigated, 100 and 200 m³/d, correspond to the water-gravity numbers 6.3 to 3.1 for our reservoir properties. We applied this injection strategy using vertical producers with two injection configurations: single vertical injector and a pair of horizontal parallel laterals in a simplified representation of the unconsolidated Forest sand found offshore Trinidad. Twelve simulation runs were conducted, varying injection-gas composition for miscible- and immiscible-gas drives, water-injection rate, and injection-well orientation. Our results show that water-over-gas injection can realize oil recoveries ranging from 17 to 30%. In each instance, more than 50% of injected CO₂ remained in the reservoir, with less than 15% of the retained CO₂ in the mobile phase.

© 2013. Society of Petroleum Engineers

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History

• Original manuscript received: 28 June 2011
• Meeting paper published: 30 October 2011
• Revised manuscript received: 12 October 2012
• Manuscript approved: 15 October 2012
• Published online: 22 February 2013
• Version of record: 5 April 2013