Logs Evaluation Of Rock Mechanics And Fracturing For Shale Gas Reservoir

It is difficult to exploit shale gas reservoir under natural conditions because of the characteristics of low porosity and low permeability.Fracturing must be carried out to improve production.Fracturing index is an important parameter for evaluating whether complex fractures could occur after fracturing and improving oil and gas productivity.The relationship between the young's modulus,Poisson's ratio,compressive strength and the stress and strain during rock fracturing was explored with rock mechanics experiments on rock samples,and the rock brittleness index based on the elastic modulus and mineral composition was calculated by using the data of cross-dipole sonic logging,natural gamma logging and density logging.Combined with the development of structural fractures and the characteristics of formation seepage,a new comprehensive evaluation model of fracturing index based on rock mechanics was established.The experimental results show that the elastic modulus parameters calculated with time difference and density obtained by the cross-dipole sound wave and the density log can effectively make up the indoor core mechanics experiment and reflect the brittleness index of the continuous formation,and the shale content could be indirectly characterized by use of natural gamma log.Compared with the actual construction parameters,it is found that the higher the rock brittleness index and the smaller the difference of in-situ stress,the higher the fracturing index.The dense seams network could be produced after the fracturing,and the cracks will expand sufficiently to increase the output.