Enhancing development efficiency of conve-ntional reservoir by cyclical steam stimulation

Economic and technological feasibilities of cyclical steam stimulation (CSS) in three types of conventional reservoirs are discussed. For waxy low-permeability reservoir, feasibility of CSS to enhance development efficiency is studied by physical and numerical simulations, the field experiment in the two production wells in the Chaoyanggou low-permeability reservoir, periphery of Daqing Oilfield, shows that CSS is an effective stimulation method. For Fuyu water-drive conventional reservoir in the Jilin Oilfield, feasibility of converting to steam displacing is investigated by using reservoir engineering method, development index and economic profit prediction of one well group are given, the study demonstrates that the increased recovery may be over 20% if water-driving changes to steam-displacing. Feasibility of changing polymer-driving of Daqing Oilfield to steam displacing is studied by physical and numerical simulations, the mechanisms of enhancing recovery by steam-displacing and polymer-driving are analyzed by comparison, elementary investigation shows that the recovery of this kind of reservoir can be increased more than 10% if it changes to steam displacing.