基于动静态测井测试资料的CO2气窜通道识别与治理OA

Aiming at the challenges including the easy occurrence of CO2 channeling,difficulty in identifying channeling pathways,and insufficient basis for regulation and control during CO2 flooding development of ultra-low permeability Chang8 reservoirs in the Ordos basin,this paper integrates geological,logging,monitoring and production data to construct a comprehensive evaluation and control technology for CO2 flooding gas channeling,which covers accurate identification of natural fractures,dynamic-static combined analysis of gas flooding performance,and integrated modeling and numerical simulation.The research results show that:①An improved R/S analysis fracture identification method combining the Hurst index and second-order difference is established based on imaging and conventional static logging data.Compared with the identification results from electrical image logging,this method achieves a coincidence rate of 88.4%,which realizes accurate quantification of reservoir fracture development and lays a solid foundation for the identification of gas channeling paths.②Dynamic and static data including reservoir high-permeability strips,fracture distribution,injection profiles and wellhead CO2 concentration responses are analyzed to clarify the corresponding relationships between preferential seepage channels and gas breakthrough as well as production decline in oil wells.③A heterogeneous reservoir mechanistic model is built to determine the timing and geological conditions for gas channeling control.The control window is defined as a gas-oil ratio(GOR)of 550～2 500 m3/m3,and the geological thresholds for classified control are permeability contrast ratios of 5,10 and 30.④The integrated modeling and numerical simulation technology is adopted to iteratively calibrate the reservoir numerical model with a history matching accuracy of 90%,which accurately characterizes preferential seepage channels.The injection-production scheme is further optimized on the numerical model,a differentiated regulation strategy is proposed,and the optimal asynchronous injection-production cycle of 1 to 2 months is confirmed.The proposed technology can effectively restrain invalid gas channeling and simultaneously improve oil displacement efficiency and CO2 geological storage performance.The research outcomes provide reliable comprehensive log evaluation technical support for the efficient development of CO2 flooding in ultra-low permeability reservoirs.