Fracability evaluation of sandstone-shale interbedded reservoir in Daqingzijing area，Songliao Basin
SUO Yu1，2，3，4，SU Xianheng1，HE Wenyuan5，FU Xiaofei1，PAN Zhejun1
(1. School of Petroleum Engineering，Northeast Petroleum University，Daqing，Heilongjiang 163318，China；2. Postdoctoral Resource Center，Daqing Oilfield Company Limited，Daqing，Heilongjiang 163318，China；3. Key Laboratory of Continental Shale Hydrocarbon Accumulation and Efficient Development，Ministry of Education，Northeast Petroleum University，Daqing，Heilongjiang 163318，China；4. Heilongjiang Province Key Laboratory of Oil and Gas Reservoir Fracturing and
Evaluation，Daqing，Heilongjiang 163318，China；5. China National Oil and Gas Exploration and
Development Company Ltd.，Beijing 100029，China)
Abstract：The evaluation of reservoir fracturability is an effective method to characterize the difficulty of reservoir effective reconstruction and to judge the“sweet spots”for fracturing. However，the current domestic and foreign evaluation methods for reservoir fracturability do not fully consider the multi-lithology combination stratification. This article takes the sand-shale interbedded reservoir of Qingshankou Formation in Daqingzi area of Songliao Basin as the research object，and carries out X-ray diffraction and mechanical experiments on sandstone and shale at different depths. A new brittleness evaluation method based on the energy evolution and different stages of brittleness sensitivity index in the stress-strain curve is established through fuzzy analytic hierarchy process. The brittleness index of composite rock is analyzed and quantitatively evaluated，and the brittleness index of composite rock is combined with mineral content and cohesive strength to establish a fracturability evaluation system for multi-lithology composite reservoir. Experimental evaluation results show that the uniaxial and triaxial compressive strength of composite rock samples decrease with the decrease of shale interbed thickness，but the brittleness index first decreases and then increases with the decrease of shale interbed thickness，and the fracturability index decreases with the increase of confining pressure. By conducting continuous coring，mechanical experiments and mineral content tests，the curve of fracturability index changing with burial depth is plotted，and the results of on-site microseismic monitoring are compared with the corresponding burial depth reservoir fracturability index，which validates the accuracy and feasibility of this fracturability evaluation method. The research results can provide reference for fracturing transformation of multi-lithology composite layered reservoirs.
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2024, Vol. 43 
