煤岩气地质-工程甜点要素地震表征与预测OA

There are abundant coal-rock gas resources in China,but their exploration faces the difficulties like low accuracy of conventional seismic prediction and unclear geophysical characterization of sweet spot elements,which restricts the efficient development of coal-rock gas.Taking the Yichuan area of the Ordos Basin as an example,this paper innovatively establishes a seismic quantitative characterization method for geological and engineering parameters of thin coal seams and constructs a multi-element collaborative prediction technology system for sweet spots of coal-rock gas by using logging,"broadband,wide-azimuth,high-density,high-fidelity"3D seismic,fracturing engineering,and production test data comprehensively.The following results are obtained.First,the elastic parameters are calculated by virtue of the multi-level facies-controlled pre-stack geostatistical inversion under constraint of petrophysical analysis,and a quantitative relationship model is established based on the logging evaluation results.In this way,the spatial distribution and gas content of thin coal seams can be predicted effectively.Second,regarding the strong reservoir heterogeneity,dual porosity,and coexisting free and adsorbed gas in coal-rock gas reservoirs,a geological sweet spot characterization factor based on coal thickness and gas content is innovatively proposed,which enables the distribution prediction of geological sweet spots.Third,the application of facies-controlled pre-stack geostatistical inversion and pre-stack anisotropic inversion technologies promotes the quantitative evaluation of key engineering parameters,such as horizontal principal stress difference and fracture development intensity in coal seams.Fourth,it is indicated that fracture development intensity and horizontal principal stress difference are the main factors controlling engineering sweet spots,and the engineering sweet spot characterization factor constructed on the basis of multiple regression enables the prediction of engineering sweet spots.In conclusion,the research results play a crucial role in target selection,horizontal well deployment and implementation,and fracturing scheme design.They have contributed to the submission of proven geological reserves of coal-rock gas exceeding 100 billion cubic meters in the Yichuan area,providing technical reference and guidance for coal-rock gas exploration and development under similar geological conditions.