The Influence of Reservoir Temperature on the Micromechanical Properties of Shale
The temperature of deep shale gas reservoir is high,in order to study the impact of formation tempera-ture on the macroscopic and microscopic mechanical properties of shale,the grid micro-indentation experiments at 26℃,80℃and 150℃were carried out to simulate surface,middle and deep reservoir temperature for the shale cores of the Cambrian Longmaxi Formation in Changning Block,Sichuan Basin.The influence of temperature on the microscopic mechanical properties of the shale rocks in the Longmaxi Formation was evaluated by using the deconvolution data statistical analysis method.The impact of temperature on micro-scale fracture toughness was illustrated through energy analysis,furthermore,the mechanism of temperature on the conductivity of deep shale fractures was analyzed.The results show that the temperature of deep reservoir significantly weakens the micro-e-lastic modulus,hardness and fracture toughness of shale;from the energy analysis,the proportion of elastic ener-gy in the total energy of the indentation point is positively correlated with the experimental temperature.It is proved that with the increase of the experimental temperature,the proportion of elastic energy in the total energy of the indentation point increases,which promotes the elastic deformation of the point.The enhancement of elas-tic deformation ability leads to the ability of mineral clusters to recover elastic deformation after being stressed,which further explains that the elastic deformation of minerals around fractures is easy to recover after the expan-sion of hydraulic fractures.The hydraulic fracture would be easy to close after opening and difficult to maintain.These research findings offer theoretical support for comprehending the low conductivity of hydraulic fractures in deep shale gas reservoirs from micro rock mechanics perspective.
deep shale gas reservoirreservoir temperaturerock mechanicsmicroindentationhydraulic fracture