Three-Dimensional Multiparameter Modeling of Shale Reservoirs and Geostress Research

Shale reservoirs have the characteristics of low porosity and low permeability. The reservoir geological structure is complex, and the heterogeneity is strong in the lower of Es3 and upper of Es4 in the central uplift zone of Dongying Depression, making it crucial to clarify the distribution of reservoir properties and geostress in the study area to evaluate the reservoir. Therefore, this paper establishes a three-dimensional geological tectonic model and a three-dimensional distribution model of reservoir physical properties and rock elasticity parameters, constructs a geomechanical finite element model of the study area, and carries out a three-dimensional geostress study. The research results show that (1) the lithology of the study area is mainly divided into shale and sandstone; the shale is well developed, has strong continuity, and is distributed in uplift and depression areas; and sandstone is underdeveloped and random, mainly distributed in the depression area, (2) the influence of rock phase porosity and permeability is significant; compared with sandstone, shale has poor porosity and permeability; and given the increase in porosity, the permeability of the shale reservoir gradually increases, (3) vertically, given an increase in depth, the Poisson’s ratio of the reservoir rock gradually decreases, and the elastic modulus gradually increases; horizontally, shale has a larger Poisson’s ratio and a smaller elastic modulus compared to sandstone, and (4) most of the single wells exhibit a small change in geostress, and sudden changes in geostress occur in some well sections. The maximum and minimum horizontal principal stresses in the study area increase with depth, in which the uplift and depression zones produce local sudden changes in ground stress, which can easily cause cracks to develop.