渗透率级差对透镜状砂体成藏的控制模式

根据对东营凹陷牛35岩性油气藏充满度(含油砂体体积占砂体总体积的百分比)及其控制因素的重点解剖，结合4组物理模拟实验结果，认为渗透率级差是控制砂体充满度大小最主要的因素，砂体非均质性对砂体中的油水分布和充满度起至关重要的作用。在此基础上，提出储集层非均质性对封闭体系中砂体成藏的控制模式，即垂向上中等渗透率的砂体是油气运移和充注的首要目标，其充满度最大，在油气充足的情况下，渗透率最大的砂体是随后油气充注的理想场所；在渗透率级差更大的情况下，渗透率最大的砂体是油气充注的首选目标，充满度最高，其次向渗透率中等的砂体充注。在岩性圈闭的油气运聚成藏过程中，成藏的主要动力可能是地层压差，而不是浮力。图7表3参9

Controlling model of permeability difference on the hydrocarbon accumulation of sand lens reservoirs

Analyses of the oil fullness degree of Niu 35 Sands in the Dongying Sag, and its controlling factors, combining with the experimental results of four simulations, indicate that permeability difference is the most important controlling factor to oil fullness degree of sands. The heterogeneity of porosity and permeability of sands has critical effect on distribution of oil and water within the sands and their fullness degree. A model has been built up, in which the heterogeneity within the reservoir controls the oil accumulation in a confined sand body. Oil migrates and accumulates in sands with the middle permeability in vertical direction firstly, and the sand body's fullness degree is the highest ones. The sands with largest permeability can also become favorable accumulation rooms if oil source is of abundance. However, oil will accumulate firstly in the sands with largest permeability if the permeability difference is large enough, then accumulates in sands with middle permeability. The formation pressure difference, not buoyancy, may be the main dynamics for hydrocarbon accumulation in lithological reservoirs.