济阳坳陷超压和应力场对页岩油富集的影响

Influence of overpressure and stress on shale oil enrichment in Jiyang Depression

包友书

BAO Youshu

中国石化胜利油田分公司勘探开发研究院，山东 东营 257015

Research Institute of Exploration and Development, Shengli Oilfield Company, SINOPEC, Dongying 257015, China

为了探索济阳坳陷超压和应力场对页岩油富集的影响，文中研究了现今超压的发育特点、应力场特征和应力裂缝发育规律。研究表明：济阳坳陷现今超压主要为古近系沙河街组泥页岩生烃增压成因，页岩滞留烃富集段与自源超压段、次生孔隙发育段有较好对应性。构造应力场最大主应力由垂向应力转换为水平应力的起始深度为2 800 m，与页岩滞留烃大量富集的起始深度相对应。泥页岩岩心中可识别4类典型的水平应力为最大主应力成因的裂缝。济阳坳陷页岩油富集段应力场与流体压力耦合，有利于形成裂缝及微裂缝有效储集层，在局部应力集中带形成泥岩裂缝型油藏。

To research the effect of fluid pressure and stress on shale oil enrichment in Paleogene of Jiyang Depression, the overpressure occurrence character of nowadays and its genesis, the stress field characteristics and stress-caused factures are investigated in this paper. The results show that the overpressure in Paleogene of Jiyang depression is mainly owing to hydrocarbon-generating pressurization of source rock shale of Shahejie Formation, and the depth interval of oil-enrichment shale has good relationship with self-sourced overpressure and secondary pore development. The starting transformation depth of maximum principal stress from vertical stress to horizontal stress in Jiyang Depression is about 2,800 m, which matches well with the main initial depth of large amount of shale oil accumulation. Four categories of horizontal stress-induced fractures in shale of Shahejie Formation are identified according to their spatial occurrence state. The coupling of horizontal stress and overpressure in shale of Shahejie Formaiton of Jiyang Depression is favorable for fracture and micro-fracture forming, which provides the effective reserving space for shale oil storage. Even the fracture shale oil reservoirs can be formed in some stress concentration zone.

10.6056/dkyqt201805008