东营凹陷岩性油藏成藏机制研究

东营凹陷已进入以岩性油藏为重要目标的勘探阶段，必须深化岩性油藏成藏机制研究。东营凹陷沙三段烃源岩具有异常高流体压力，处于其内的透镜状砂体能否形成岩性油藏，取决于成藏动力与成藏阻力的相对大小。烃源岩的剩余围岩压力是成藏动力，砂体周缘的突破压力是成藏阻力，将前者除以后者的商作为成藏指数，可用于评价岩性圈闭的成藏条件。东营凹陷岩性油藏的勘探证实，成藏指数与砂体的含油程度具有正相关性，用成藏指数评价岩性圈闭的成藏条件，比分别用剩余围岩压力或突破压力评价更科学，评价精度更高。

Forming mechanism of lithologic reservoirs in Dongying sag

Dongying sag has been of exploration stage aimed to lithologic reservoirs, so it s necessary to study forming mechanism of lithologic reservoir in detail. Source rocks in the third member stratum of Shahejie Fomation of Dongying sag have fluid superpressure. Whether sand lens reservoirs among source rock that can form lithologic reservoirs lies on the location between power and resistance force of oil accumulation. Suplus pressure in the wall rock outside resource rock is power of oil accumulation, breaking pressure around sandstone is resistance force of oil accumulation. Reservoir forming index is defined as a parameter of the ratio of reservoir forming power over the reservoir forming resistance, which can be used to evaluate condition for forming lithologic trap. Exploration of lithologic oil reservoirs proves that the relation between reservoir forming index and oil-bearing extent is in positive correlation. Evaluating lithologic trap by using the reservoir forming index is more scientific and preciser than suplus pressure in the wall rock or breaking pressure.