Macroscopic Heterogeneity Controlling Factors of Deepwater Gravity Flow Reservoirs: A case Study of Chang 6₃ in Huaqing Area

Macroscopic heterogeneity is an important controlling factor for the evaluation of oil-bearing reservoirs. The macro-heterogeneity of deep-water gravity flow reservoirs is rather strong, which is a primary difficult problem of oil and gas exploration and development. Through the analysis of deep-water gravity flow sedimentary theory, core observation, logging data and experimental test, etc, the macro-heterogeneity characteristics of Chang 6₃ deep-water gravity flow reservoir in Huaqing area of Ordos Basin are described. The research shows that Chang 6₃ in Huaqing area has a strong in-layer heterogeneity, mainly including turbidite, sloping rock, sandy debris flow and argillaceous debris flow. The interlayer is divided into three types:argillaceous, calcareous and gravel. The frequency of argillaceous interlayer is high, which has a great influence on the internal heterogeneity of sediment. The calcareous interlayer mainly appears in the sandy debris flow; The gravity flow sediment sand bodies are divided into four categories, continuous overlapping type, interval overlapping type, lateral pinch-out type and sand-mud interbedding type, with the interlayer heterogeneity from weak to strong. Analyzing the distribution of sand body thickness and sedimentary microfacies, pore infiltration, flow unit and other influencing factors in the study area, and the plane distribution of macroscopic heterogeneity of Huaqing Chang 6₃ reservoir was obtained. It summarizes three influencing factors, establishing a comprehensive evaluation table that affects the macroscopic heterogeneity of the reservoir, so as to provide assistance for oilfield exploration and development.