Improved Heavy-Oil Recovery by Separated-Zones Horizontal-Well Steam Stimulation
- Liguo Zhong (Northeast Petroleum University) | Shoujun Zhang (China National Petroleum Corporation) | Fei Wu (China National Petroleum Corporation) | Baoshan Lang (China National Petroleum Corporation) | Heng Liu (Liaohe Oilfield Company)
- Document ID
- Society of Petroleum Engineers
- Journal of Canadian Petroleum Technology
- Publication Date
- March 2012
- Document Type
- Journal Paper
- 106 - 114
- 2012. Society of Petroleum Engineers
- 5.4.6 Thermal Methods, 4.1.5 Processing Equipment, 6.5.5 Oil and Chemical Spills, 4.1.2 Separation and Treating, 5.3.9 Steam Assisted Gravity Drainage, 1.6 Drilling Operations, 5.1.1 Exploration, Development, Structural Geology, 2.4.3 Sand/Solids Control
- separated zones, steam injection, steam conformance, horizontal well
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Horizontal wells are widely drilled to produce heavy oil because of their large reservoir contact. For example, there are more than 500 horizontal wells operated in cyclic-steam-stimulation (CSS) or steam-assisted gravity-drainage (SAGD) processes in Liaohe oil field. The length of these horizontal wells usually ranges from 100 to 500 m. But it is challenging to recover oil along a horizontal well proportionally by conventional steam-injection processes because of poor steam conformance along the horizontal well, which is derived from reservoir heterogeneity, large horizontal-well length, and steam properties. Field investigation shows that only half of the reservoir along the horizontal well is well steamed and recovered, and that the average ratio of oil production to steam injection (OSR) is less than 0.28. In this paper, a separated-zones steam-injection process is introduced to improve steam conformance along the horizontal well; in this process, in which packers, outlets, pressure-sensitive valves, and ball sealers are involved, steam could be injected to the selected zone, separated dual zones in sequence or at one time, or separated multizones simultaneously. In order to investigate steam conformance along the horizontal well and feasibility of separated-zones steam injection, primary laboratory experiments with a sand-packaged model, numerical simulation, and field testing are carried out. These show that steam injected to separated zones could be regulated with sealed packer(s) based on the principles of steam crossflow and superimposing the effect near the packer; therefore, steam conformance along the horizontal well could be considerably improved by separated-zones steam injection. Field testing of 76 wells stimulated by separated-zones steam injection shows that up to 70% of the reservoir along the horizontal well is well steamed on average, and steam conformance is significantly improved.
|File Size||2 MB||Number of Pages||9|
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