Abstract:

Reservoir heterogeneity is one of the important factors that affect remaining oil distribution. In recent years, retention phenomenon of remaining oil in Taiyangwan area is serious. In view of this phenomenon, accorded to the practical geological situation, geological data of lithologies, physical properties, electric properties and oiliness were adopted to conduct qualitative evaluation of Chang 2 reservoir heterogeneity and its cause, and to analyze the influences of heterogeneity on remaining oil distribution of the reservoir. By using experiment，logging and standard contrast methods, this paper divided heterogeneity into the intra-layer, inter-layer, plane and microscopic heterogeneities for respective discussion. The result shows that the intra-layer heterogeneity is strong in the study area, which is mainly controlled by sedimentary structure, rhythm, permeability and interlayers; inter-layer heterogeneity is generally strong with uneven development in each layer, the heterogeneity of the Chang 2³ is the strongest, followed by Chang 2¹ and Chang 2²; the plane heterogeneity is mainly affected by the distribution of sand body and sedimentary microfacies; pore structure at micro level is complex, and various diagenesis heightened reservoir heterogeneity degree. The research of the reservoir heterogeneity provides important theory basis for grasping the distribution of remaining oil and later exploitation in the study area.

Key words: sedimentary facies of carbonate, sedimentary evolution, Tuqiaozi Formation, Ganxi section