Application of direct inversion of reservoir parameters in 'sweet spot' reservoir prediction: A case study of Baisan Formation in Junggar Basin

摘要

The sandy conglomerate of Baisan Formation in Junggar Basin is widely distributed, which is characterized by low porosity and permeability. "Sweet spot" reservoir prediction is the key factor to realize the economic development of oilfield. Reservoir physical parameters are the important parameters of "sweet spot" reservoir prediction. Accurate prediction of reservoir physical parameters is an important basis for reservoir evaluation and well location determination. In this paper, the relationship between elastic parameters and related reservoir physical parameters is established by using rock physical model, and the reservoir physical parameters are obtained by pre-stack inversion method, so as to carry out reservoir "sweet spot" prediction. Firstly, the linear regression analysis of well data is carried out to obtain a new rock physical model, and the relationship between P-S wave velocity and rock physical parameters is established. Secondly, by introducing the rock physical model into the linear expression of Aki's reflection coefficient, we derive the approximate equation of reflection coefficient of oil-bearing porosity, lithological indicator factor and density. The equation lays a theoretical foundation for reservoir physical property inversion. The AVO inversion results of actual data are obtained by this method, and compared with known well data. The results show that the method can obtain reliable reservoir parameters directly from seismic data, and then predict reservoir physical properties "sweet spot".