Four fundamental principles for design and follow-up of steam flooding in heavy oil reservoirs

Numerical simulation is used to understand the impacts of steam injection rate,bottom-hole steam quality,production/injection ratio and reservoir pressure on the performance of steam flooding in heavy oil reservoirs,providing the concrete ranges of quantified indices.For conventional heavy oil reservoirs,to realize better performance by steam flooding,the following conditions must be met:(1)steam injection rate should not be less than 1.6 m3/(d·hm2·m),thus keeping the continuous extension of steam chamber and maintaining the bottom hole steam quality;(2)bottom hole steam quality should not be less than 40%,which reflects the requirement of enthalpy for unit injected fluid by steam flooding;(3)reservoir pressure should be less than 5.0 MPa,had better in 1.0-3.0 MPa,thus maintaining a lower reservoir pressure to improve the swept volume of steam;(4)instant production/injection ratio should not be less than 1.2 during the stable stage of steam flooding,realizing practical steam flooding.The design,follow-up and evaluation of steam flooding in pilot test and extension test in Qi40 Block of Liaohe Oilfield show that the quantified indices have become four fundamental principles for such design,follow-up and evaluation.