Optimizing recovery after CSS

Technical paper on optimizing gravity assisted steam flooding in China's massive Liaohe oilfield.

As a follow-on to a previous blog I posted describing an optimization framework for CSS followed by SAGD , I wanted to share a related paper published and presented at the International Oil & Gas Conference and Exhibition in China, 5-7 December. The technical paper SPE 104405-MS titled “Efficient Technology Following Cyclic Steam Stimulation for Thick Massive Heavy Oil Reservoirs” by authors Shangqi Liu, Yongrong Gao, and Shuangmao Liu, PetroChina Co. Ltd describes the use of a high temperature 3-D physical model combined with thermal numerical simulation to optimize gravity assisted steam flooding using both vertical and horizontal wells compared to conventional SAGD. The study area was the massive heavy oil reservoirs of PetroChina’s Liaohe Oilfield.

The initial phase of production in these reservoirs typically involves CSS which leaves a significant portion of the lower reservoir unswept due to steam override and reservoir anisotropy. The challenge to operators is then what recovery methods following CSS should be used to maximize recovery ?

Results of the lab and numerical simulation indicated that a combination of vertical and horizontal wells actually yielded better recovery compared to SAGD.

Care should be taken in applying these results to other reservoir environments but the idea is that a combination of lab models and thermal simulation are a cost effective way to optimize heavy oil recovery before expensive field strategies are put in place.

Jorge.