张性盆地高温砂岩储层发育控制因素:以珠江口盆地文昌A凹陷为例

发布时间：2018-12-20 15:44

【摘要】：珠江口盆地西缘文昌A凹陷6号断裂带珠海组二、三段由于处于高地温环境,经历了较强的成岩改造,形成原生孔和次生溶孔比例相当的孔隙特征,发育低-中渗砂岩储层,平均孔隙度7.76%,而渗透率普遍小于2.5×10-3μm2。目前,该低渗储层形成的控制因素尚不清楚。通过物性测试、铸体薄片和扫描电镜等综合分析了储层低渗原因与优质储层发育控制因素。研究表明:文昌A凹陷珠海组二段埋深大于3 400m,发育扇三角洲前缘相,砂岩粒度粗,但成分成熟度偏低,且岩性变化大、泥质含量较高,造成抗压实能力相对较弱;其次,早期孔隙流体呈酸性,粒间缺乏早期碳酸盐胶结物,造成压实程度加大;绿泥石和伊蒙混层对喉道的堵塞也是该区低渗原因之一;该段中-粗砂岩储层经历了大气淡水溶蚀、有机酸溶蚀和热液溶蚀,其中晚期热液溶蚀对孔隙度增大有重要贡献。珠海组三段发育潮坪相,以特低渗储层为主,低渗的原因主要是砂岩粒度细,埋藏深,压实较强;其次,早期孔隙流体呈碱性,存在大量碳酸盐胶结物,以及局部层位石英次生加大强烈,造成特低渗;该段细砂岩原生孔隙较发育,其保存与绿泥石环边有关;由于强压实和绿泥石的堵塞作用导致喉道细小,孔喉半径比范围较大;高温强成岩背景下的低渗砂岩储层形成原因是该套砂岩储层分布预测的重要地质依据。
[Abstract]:The second and third members of the No. 6 fault zone of Wenchang A depression in the western margin of Pearl River mouth basin have undergone strong diagenetic transformation due to their high geothermal environment, forming pore characteristics with the same proportion of primary pore and secondary dissolved pore, and developing low to medium permeability sandstone reservoirs. The average porosity is 7.76 and the permeability is less than 2.5 脳 10 ~ (-3) 渭 m ~ (2). At present, the controlling factors of the formation of the low permeability reservoir are not clear. Through physical property test, casting sheet and scanning electron microscope, the reasons of reservoir low permeability and the controlling factors of high quality reservoir development are analyzed. The results show that the second member of Zhuhai formation in Wenchang A depression has a buried depth greater than 3 400 m, developed fan delta front facies, coarse grain size of sandstone, but low compositional maturity, large lithologic change and high muddy content, resulting in relatively weak compaction resistance. Secondly, the early pore fluid was acidic, and the lack of early carbonate cement between grains resulted in increased compaction, and the blockage of the throat in chlorite and eumonium was also one of the reasons for the low permeability in the area. The medium-coarse sandstone reservoir has experienced atmospheric fresh water corrosion organic acid dissolution and hydrothermal dissolution. The late hydrothermal dissolution contributes significantly to the increase of porosity. The tidal flat facies are developed in the third member of the Zhuhai formation. The main reason for the low permeability is the fine grain size of sandstone, deep burial and strong compaction. Secondly, the early pore fluid is alkaline, there are a large number of carbonate cementation, and the local quartz secondary increase, resulting in extremely low permeability, the fine sandstone primary pore is relatively developed, its preservation is related to the chlorite ring edge; Due to the strong compaction and the clogging of chlorite, the throat is small and the radius of pore throat is large, and the formation of low permeability sandstone reservoir in high temperature and strong diagenetic background is the important geological basis for predicting the distribution of sandstone reservoir.
【作者单位】：中海石油(中国)有限公司湛江分公司;成都理工大学能源学院;西南石油大学油气藏地质及开发工程国家重点实验室;
【基金】：“十二五”国家科技重大专项“南海西部海域典型低孔低渗油气藏勘探开发关键技术研究及实践”(CNOOCKJ125ZDXM07LTD02ZJ11)
【分类号】：P618.13

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