毛细管力的初次运移及成藏作用有效性分析  

Effectiveness of Capillary Pressure on the Primary Migration of Oil and Its Accumulation

作　　者：包友书[1] 张林晔[1,2] 张守春[1] 徐大庆[1] 王宇蓉[1] 张蕾[1] 吴连波[1] 

机构地区：[1]中国石化胜利油田分公司勘探开发研究院,东营257015 [2]西北大学地质学系大陆动力学国家重点实验室,西安710069

出　　处：《高校地质学报》2017年第2期296-303,共8页Geological Journal of China Universities

基　　金：国家自然科学基金项目(41372129;41072096);国家973课题(2014CB239101;2014CB239105);中石化科技攻关项目(P15117)联合资助

摘　　要：毛细管压力差通常被认为是油气初次运移及源内成藏的重要动力,但毛细管力驱动油由小孔向大孔迁移的前提是岩石孔隙表面亲水。文章结合东营凹陷沙三中亚段成熟烃源岩内砂体含油概率较低,且原油多非来自成熟源岩围岩情况,对砂岩及页岩的润湿性进行了探讨。东营凹陷部分砂岩存在润湿性反转,与较高的非烃及沥青质含量的原油接触,是砂岩润湿性反转的主要原因;而泥页岩烃源岩在大量生烃演化过程中,其整体润湿性也表现为中间润湿甚至亲油性。润湿性改变导致毛细管压力方向改变,初次运移及源内油藏成藏作用减弱甚至消失,是沙三中亚段成熟源岩内砂体含油概率低的主要原因。据此认为,对于高丰度的生烃早期阶段的泥页岩烃源岩,毛细管力作为初次运移及源内油藏成藏动力的作用可能是有限的。The difference of capillary pressures acting on oil droplet is commonly considered as the critical force for the primary migration of oil and driving oil to accumulate in reservoirs in source sequences. The prerequisite for the oil migration from thinner pores to larger pores under the force of capillary pressure is that pore surface is water wet. In this study, we address the wettablities of sandstones and shales in the Middle Layer of the 3rd Member of the Shahejie formation（E53m）of the Dongying depression,and discuss the impact of wettablity on capillary force and roles on oil migration. In the study area,lots of E53m sandstones that are surrounded by mature source roks have relatively low oil-bearing levels and majority of the oils found in these reservoirs are not from the surrounding source rocks but from deeper source rocks. Some sandstones in the study area have wettability reversal from water-wet to oil-wet,which is caused by that the sandstones are contacted with oil with high abundance of NSO and asphaltenes. The shale source rocks show neutrally wet to oil wet in general during the hydrocarbon generation. Owing to the change of wettability of rock surface, the direction of capillary force is altered correspondingly, which further leads to the capillary force being invalid for driving oil primary migration or accumulation to inner-source rock reservoirs. The wettability reversal is one of the possible reasons causing the low oil-bearing level of the Es3msandstones. We suggest that for the source rocks with high organic richness and relatively low maturity, the efficiency of capillary pressure acting as force to drive oil primary migration or accumulation to inner-source rock reservoirs may be limited.

关 键 词：毛细管力 初次运移 成藏动力 润湿性 润湿性反转 东营凹陷 

分 类 号：P618.13[天文地球—矿床学]