The Characteristics of Microscopic Heterogeneity and Its Influence on Imbibition in Shale Oil Reservoirs in Permian Lucaogou Formation, Jimsar Sag, Junggar Basinjin

In this paper, we analyze the microscopic heterogeneity of the Lucaogou formation in Jimsar with the introduction of the “Umbrella deconstruction” method. The percolation and absorption modes and operation characteristics of shale oil are explored by the combined percolation and magnetic resonance test, and we investigate the effect of microscopic heterogeneity on imbibition. The results show that the pore structure has strong heterogeneity. Specifically, with the change in the angle of the umbrella deconstruction slice, the pore size parameters show the characteristic of periodic change, while the pore morphology parameters have an obvious extremum. The distribution of chemical elements is different, and there is iron in some sections. According to the T2 relaxation time spectrum curves of different infiltration and absorption times, the unsteady multi-scale linkage infiltration and absorption model of shale oil in the Lucaogou formation is first proposed. According to the characteristics of infiltration suction, there are three types of staggered and turbulent suction: double-arch and single-arch. The effects of three types of imbibition are weakened in turn. In general, the heterogeneity of pore structure and chemical elements is closely related to imbibition characteristics. The anisotropy of the pore long axis is negatively correlated with the efficiency of imbibition, and the anisotropy of the pore shape factor is negatively correlated with the active degree of imbibition. Iron is an important criterion for the exclusion of the type of staggered and turbulent, and the type of double-arch can be excluded according to the sulfur element. It is also found that the silicon content mainly affects the efficiency of imbibition in macropores. The study in this paper is helpful to clarify the relationship between microscopic heterogeneity and the characteristics of imbibition, which is of great significance for exerting the effect of imbibition displacement and improving the efficient production of shale oil.