恩平凹陷珠江组盖层的沉积学评价思路与方法  

Ideas and methods of sedimentologic evaluation on caprocks in Zhujiang Formation,Enping Sag

作　　者：王维[1,2] 杨香华[1,2] 叶加仁[1,2] 舒誉 吴静 

机构地区：[1]中国地质大学构造与油气资源教育部重点实验室,武汉430074 [2]中国地质大学资源学院,武汉430074 [3]中海石油(中国)有限公司深圳分公司,广州510240

出　　处：《石油实验地质》2014年第2期249-256,共8页Petroleum Geology & Experiment

基　　金：国家重大油气专项课题(2011ZX05023-001-015);国家重大油气专项课题(2011ZX05023-001-001);国家自然科学基金项目(40702024)联合资助

摘　　要：恩平凹陷主要目的层段珠江组含砂率较高,泥质盖层封堵能力差异较大,盖层成为油气成藏的关键制约因素。由于珠江组泥岩松散,泥岩岩心无法满足传统盖层测试分析的样品要求。为此借鉴页岩气储层评价思路,对泥岩盖层的微观孔隙、微裂缝发育程度进行评价,然后通过分析脆性矿物含量、黏土矿物类型等与沉积微相的成因关系,对盖层封堵性进行分析与预测。伴随海侵范围扩大,珠江组上段主体位于三角洲前缘亚相,其中分支流河道间湾微相泥岩中发育片状伊利石与草莓状黄铁矿,水下分支流河道侧翼微相泥岩中高岭石含量较高,且含有石英颗粒。泥岩微相类型与油气分布对应关系表明分支流河道间湾微相泥岩盖层封堵性能好,而水下分支流河道侧翼微相泥岩盖层封堵性能较差。含石英等陆源脆性矿物较高泥岩的测井密度值相对较低,密度曲线波动较大。通过对泥岩盖层进行泥岩含量反演与井震联合分析,预测了优质盖层发育的微相类型与有利部位。As the main exploration target in the Enping Sag, the Zhujiang Formation is rich in sandstones. The sealing capacity of muddy cap rocks varies obviously. Explorations have indicated that the cap rocks controlled hydrocarbon accumulation. As the mudstones in the Zhujiang Formation are generally loose, the mudstone cores fail to reach the standard of traditional methods of sealing quality analysis. Referring to the ideas of shale gas res-ervoir evaluation, the development degrees of micro pores and fractures in mudstones were evaluated. The sealing capacity of muddy cap rocks were analyzed and predicted according to the relationship between brittle mineral content, clay mineral type and sedimentary microfacies. The Zhujiang Formation mainly belongs to delta front subfacies after transgression. There are flake illite and framboidal pyrite in the mudstones of interdistributary bay microfacies and the mudstones in the overbank microfacies of submarine distributary channel are rich in kaolinite and quartz particles. The correspondence between mudstone microfacies type and hydrocarbon distribution shows that the sealing capacity of mudstone cap rocks in interdistributary bay microfacies is good, while that in the flank of submarine distributary channel is bad. The well logging density of mudstones which include terrigenous brittle minerals such as quartz is relatively lower, and their density curves fluctuate greatly. The synthetic analysis of seismic, well logging and core data forecasts a favorable sedimentary microfacies and site for good cap rocks.

关 键 词：盖层评价 微观孔隙裂缝 沉积微相 珠江组 恩平凹陷 珠江口盆地 

分 类 号：TE122.25[石油与天然气工程—油气勘探]