南海高压气田泥岩盖层封闭机制、封气能力及演化过程——以莺歌海盆地X13高压气田为例

发布时间：2018-08-10 21:38

【摘要】：近期在南海莺歌海盆地勘探发现了高压大气田和一批含气圈闭,随着勘探的深入,高压领域(高压区、高压层系)天然气规模成藏和气水分布的复杂性日益凸显。利用钻井、地震和分析测试资料,对莺歌海盆地X13高压气田上中新统黄流组一段泥岩盖层的封闭机制、封气能力进行了研究,认为泥岩盖层存在物性封闭和泥岩滞排超压封闭两种封闭机制,并建立了相应的封气能力评价方法。X13高压气田泥岩盖层封气能力形成时间约在6.1Ma;3.6Ma时,X13高压气田构造-岩性圈闭形成,这也是天然气成藏的早期,储层、泥岩盖层为常压,泥岩盖层以物性封闭为主,盖层的排替压力大于储层剩余压力,因而具备了封气能力;1.8~0Ma,是天然气晚期成藏时期,储层、盖层已发育超压,泥岩盖层既存在物性封闭,也存在泥岩滞排超压封闭,泥岩盖层的排替压力与滞排超压之和大于超压储层的剩余压力,其中滞排超压发挥了主要的封气作用。较之天然气成藏早期,成藏晚期的盖层泥岩具备更好的封气能力。提出了"中部滞排欠压实-底部畅排压实型盖层—大型储集体组合"的圈闭(带)是高压领域天然气成藏富集区,这一认识对南海高压领域天然气勘探具有指导意义。
[Abstract]:High pressure atmospheric fields and a number of gas-bearing traps have been discovered recently in the Yinggehai Basin of the South China Sea. With the development of exploration, the complexity of gas reservoir formation and gas-water distribution in high-pressure area (high-pressure area, high-pressure strata) is becoming more and more obvious. Based on drilling, seismic and analytical test data, the sealing mechanism and gas sealing ability of mudstone caprock in upper Miocene Huangliu formation of X13 high pressure gas field in Yinggehai Basin are studied. It is considered that there are two sealing mechanisms in mudstone caprock: physical sealing and mudstone hysteretic overpressure sealing. The corresponding evaluation method of gas sealing ability is established. The forming time of gas sealing ability of mudstone caprock in X13 high pressure gas field is about 6.1 Ma-3.6 Ma. The tectonic-lithologic trap of X13 high pressure gas field is formed, which is also the early stage of natural gas reservoir formation, and the reservoir and mudstone caprock are under normal pressure. The mudstone caprock is dominated by physical sealing, and the displacement pressure of the caprock is larger than the residual pressure of the reservoir, so it has the ability to seal gas at 1.80.It is the late natural gas accumulation period, the reservoir, the caprock has developed overpressure, and the mudstone caprock has physical sealing. The sum of displacement pressure and hysteretic overpressure in mudstone caprock is larger than the residual pressure in overpressure reservoir, in which hysteretic overpressure plays a major role in sealing gas. Compared with the early stage of natural gas accumulation, the cap mudstone of late reservoir formation has better gas sealing ability. It is proposed that the trap (belt) of "the middle hysteretic undercompaction, the bottom undrained compacted caprock and large reservoir assemblage" is a high pressure area of natural gas accumulation and accumulation, which is of guiding significance for natural gas exploration in the high pressure area of the South China Sea.
【作者单位】：中海石油(中国)有限公司湛江分公司南海西部石油研究院;
【基金】：国家重大科技专项“海洋深水区油气勘探关键技术(三期)”的课题“琼东南盆地深水区大中型气田形成条件与勘探关键技术”(编号:2016ZX05026-02)资助的成果
【分类号】：P618.13

【参考文献】