Characteristics of shale gas reservoirs and evaluation of their gas potential in Sujiatun area, Lishu Fault Depression, Songliao Basin

In addition to the characteristics of source rocks, we should pay more attention to the evaluation of reservoir characteristics in shale oil and shale gas resource assessment, especially evaluation of fracturing and gas content which are directly involved in the mobility of resources.In this paper, we studied the hydrocarbon generation potential of mud shale as well as the fracturing properties and gas content on the basis of test results from the first member of Yingcheng Formation in well Su2 in the Sujiatun area of the Lishu Fault Depression.The results show that the mud shale from the first member of Yingcheng Formation have good shale gas generating conditions in this area.High content of brittle minerals, high Young's modulus and low Poisson's ratio make the mud shale easy to crack.The porosity and permeability of the mud shale are generally low, but there are a lot of natural fractures and micro-fractures;as well single vertical cracks are prone to form during the fracturing process.Beyond that, there are a lot of micro-nanometer pores under the electron microscope, mainly micropores and mesopores.All of these different scales of fractures and the availability of pores provide a favorable migration pathway and storage space for shale gas.During drilling, measurements and logging in the first member of Yingcheng Formation, many wells have shown a large amount of oil and gas;meanwhile, high-yield gas flows were obtained in wells Su2 and Li2.Field desorption tests showed that the averaged shale gas content in the first member of Yingcheng Formation in well Su2 is 2.5 m³/t, representing a considerable resource and a good exploration and development prospect.