鄂尔多斯盆地南部长7页岩油储层地质力学特征及可压裂性评价OA

[Objective]The Ordos Basin is a pivotal region for unconventional oil and gas production in China.The Yanchang Formation Chang 7 reservoir possesses abundant shale oil resources and significant exploration potential.Reservoir geomechanics evaluation is critical for guiding the efficient development of these resources.Characterizing the geomechanical properties of the Chang 7 shale oil reservoir and establishing a quantitative prediction model are essential for evaluating reservoir fracability and optimizing sweet spot intervals.[Methods]In this study,representative core samples were collected from the Chang 7 reservoir in the southern Ordos Basin.Geomechanical parameters,including elastic modulus,Poisson's ratio,and present-day in-situ stresses,were determined experimentally.Subsequently,a geomechanical parameter prediction model was constructed using the BP neural network based on logging data to achieve quantitative evaluation of the reservoir.[Results]The results indicate the following:The BP neural network-based model demonstrates high accuracy,with minimal error between predicted results and measured values;The key geomechanical parameters of the Chang 7 shale oil reservoir exhibit significant heterogeneity.Specifically,the elastic modulus is between 16.26 GPa and 59.12 GPa,the fracture toughness is between 0.2～1.2 MPa·m0.5,the horizontal maximum and minimum principal stress range from 20 MPa to 43 MPa,12 MPa to 38 MPa,respectively;A fracability evaluation index F was established based on these reservoir geomechanical parameters to classify the reservoir quality.The reservoirs are categorized into four levels:Class Ⅰreservoirs F>2.00,Class Ⅱ reservoirs 2.00>F>1.50,Class Ⅲ reservoirs 1.50>F>0.10,and Class Ⅳ reservoirs F<1.00.The BP neural network is an effective method for the precise prediction of reservoir geomechanical parameters.[Conclusions]These findings provide scientific guidance for the optimization of hydraulic fracturing designs in the region.