泥岩盖层减弱油源断裂输导油气能力程度研究方法
- 收稿日期:
2024-10-20
- 网络出版日期:
2025-10-17
摘要: 摘要：为了研究下部源岩发育含油气盆地泥岩盖层之上油源断裂处油气富集特征，在泥岩盖层减弱油源断裂输导油气能力机制及程度研究的基础上，利用泥岩盖层内古断距、倾角、上覆沉积载荷重量产生的古正压力、源岩古地层孔隙流体压力差和供油气能力指数，求取未穿过泥岩盖层油源断裂输导油气能力指数；再由此除以泥岩盖层古连接厚度，求取穿过泥岩盖层油源断裂输导油气能力指数，据二者相对大小构建了一种泥岩盖层减弱油源断裂输导油气能力程度研究方法，并将其应用于渤海湾盆地歧口凹陷沙一中亚段泥岩盖层减弱港东断裂向东三段输导油气能力程度的研究，结果表明：测点4-10处沙一中亚段泥岩盖层减弱港东断裂向东三段输导油气能力程度为零，测点1-3和11-12处为100％，测点3-4和10-11处介于0％-100％之间。沙一中亚段泥岩盖层减弱港东断裂向东三段输导油气能力程度相对较小的测点4-10处是油气在东三段内聚集成藏的有利部位，与当前港东断裂处沙三段油气资源主要集中在测点6-10处相符合，表明该方法用来研究泥岩盖层减弱油源断裂输导油气能力程度是可行的。
Method for assessing the degree of weakening of hydrocarbon transport capacity of oil source faults by mudstone caprocks and its application
- Received Date:
2024-10-20
- Available Online:
2025-10-17
Abstract: Abstract: In order to study the characteristics of hydrocarbon enrichment at oil source faults above mudstone caprocks in petroliferous basins with developed lower source rocks, based on the research on the mechanism and degree of weakening of hydrocarbon transport capacity of oil source faults by mudstone caprocks, we use the paleo-fault throw, dip angle, paleo-normal pressure generated by the weight of overlying sedimentary load, paleo-formation pore fluid pressure difference of source rocks, and hydrocarbon supply capacity index within the mudstone caprock to calculate the hydrocarbon transport capacity index of oil source faults that do not penetrate the mudstone caprock. Then, we divide this value by the paleo-connection thickness of the mudstone caprock to obtain the hydrocarbon transport capacity index of oil source faults that penetrate the mudstone caprock. According to the relative magnitudes of the two indices, we establish a method for assessing the degree of weakening of hydrocarbon transport capacity of oil source faults by mudstone caprocks. We apply this method to study the degree of weakening of hydrocarbon transport capacity from the Gangdong fault to the third member of the Dongying Formation (Ed3) by the mudstone caprock of the middle part of the first member of Shahejie Formation (Es1m) in the Qikou Sag of the Bohai Bay Basin. The results indicate that the degree of weakening of hydrocarbon transport capacity from the mudstone caprock of Es1m affecting the Gangdong fault to Ed3 is zero at measurement points 4-10, 100% at measurement points 1-3 and 11-12, and between 0% and 100% at measurement points 3-4 and 10-11. The measurement points 4-10, where the degree of weakening of the hydrocarbon transport capacity from the Es1m mudstone caprock to the Gangdong Fault for transporting hydrocarbons to Ed3 is relatively small, are favorable locations for the accumulation and reservoir formation of hydrocarbons supplied by the underlying third member of the Shahejie Formation (Es3) source rock in Ed3. This is consistent with the current distribution of hydrocarbons discovered in Ed3 at the Gangdong Fault, which are mainly concentrated at measurement points 6-10, indicating that the method is feasible for studying the degree of weakening of the hydrocarbon transport capacity of oil - source faults by mudstone caprocks.
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