摘要
珠江口盆地白云凹陷油气勘探逐渐从中-浅层韩江组-珠江组的常规储层转向深层-超深层珠海组-恩平组的低渗致密储层,特殊的高变地温地质背景使得储层成岩作用以及致密化机制与常规储层差别较大。综合运用铸体薄片鉴定、扫描电镜观察、物性测试、成岩过程重建和物性恢复等技术,系统分析了白云凹陷西北部低隆起-中部洼陷带古近系珠海组下段-恩平组砂岩储层的成岩过程及差异,结合构造演化背景、地层埋藏史和现今物性数据,研究了影响储层物性关系的主要因素以及储层致密化过程与机理。结果表明:珠海组下段-恩平组储层经历了较强的压实作用、2期碳酸盐胶结、3期硅质胶结和3期长石溶解作用。储层成岩作用过程中,地温梯度变化导致压实速率不同,经历不同开放-封闭体系的水-岩反应过程是不同区带物性差异的主要原因。压实作用是导致储层致密的主要因素,硅质胶结和碳酸盐胶结进一步增强了储层致密程度,溶解作用改善了储层物性。从低隆起到洼陷带,伴随地温梯度升高和埋藏深度增加,低隆起储层成岩阶段为中成岩A2期,斜坡带为中成岩B期,洼陷带为晚成岩期,成岩强度不断增加;成岩作用的差异使得储层物性演化显著不同。洼陷带储层在晚期烃类充注前已致密化,斜坡带储层在晚期烃类充注阶段逐渐致密,而低隆起区储层目前仍为低渗储层。斜坡带整体埋深小于5 km,且上覆地层具备良好封盖能力,是下部勘探的重点。
In the Baiyun Sag of the Pearl River Mouth Basin(PRMB),the oil and gas exploration targets have gradually shifted from the conventional reservoirs in the shallow to moderately deep Hanjiang-Zhujiang formations to the lowpermeability,tight reservoirs in the deep to ultra-deep Zhuhai-Enping formations.Due to their distinct geological setting of highly variable geothermal gradients,the low-permeability,tight reservoirs exhibit significantly different diagenesis and tightening mechanisms from the conventional reservoirs.Using techniques such as casting thin section observation,scanning electron microscopy(SEM),physical property tests,diagenetic reconstruction,and physical property restoration,we systematically analyze the diagenetic processes of the Paleogene sandstone reservoirs from the Zhuhai Formation's lower member to the Enping Formation in the area from the northwestern low uplift to the central sub-sag zone in the Baiyun Sag and their disparities.Considering the tectonic evolution setting,stratigraphic burial history,and current physical property data,we investigate the major factors influencing the relationships among the reservoirs' physical properties and explore their tightening processes and mechanisms.The results suggest that the reservoirs from the Zhuhai Formation's lower member to the Enping Formation have experienced intense compaction,two-stage carbonate cementation,three-stage siliceous cementation,and three-stage feldspar dissolution.During their diagenetic processes,the reservoirs exhibited varying compaction rates due to changes in geothermal gradients and underwent water-rock interactions in different openclosed systems.These are major reasons for the different physical properties of the reservoirs across various tectonic zones in the Baiyun Sag.Compaction emerged as the primary factor leading to the reservoir tightness,which was further enhanced by siliceous and carbonate cementation.In contrast,dissolution improved the physical properties of the reservoirs.From the low uplift to the sub-sag
作者
远光辉
彭光荣
张丽丽
孙辉
陈淑慧
刘浩
赵晓阳
YUAN Guanghui;PENG Guangrong;ZHANG Lili;SUN Hui;CHEN Shuhui;LIU Hao;ZHAO Xiaoyang(National Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao,Shandong 266580,China;Shenzhen Branch of CNOOC Ltd.,Shenzhen,Guangdong 518054,China;CNOOC Deepwater Development Ltd.,Shenzhen,Guangdong 518054,China)
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2024年第1期44-64,共21页
Oil & Gas Geology
基金
崂山实验室科技创新项目(LSKJ202203402)
国家自然科学基金优秀青年基金项目(42222208)
中海石油(中国)有限公司综合科研项目(KJZH-2021-0003-00)。
关键词
致密化
差异成岩作用
深层储层
古近系
白云凹陷
珠江口盆地
tightening
differential diagenesis
deep reservoir
Paleogene
Baiyun Sag
Pearl River Mouth Basin(PRMB)