摘要
成岩作用控制孔隙演化,对油气开采具有重要的指示作用。安徽无为—巢湖地区中下二叠统碳酸盐岩广泛发育,有机质丰富,多年来主要集中在地层、古生物及沉积相方面的研究,成岩作用的工作较少。镜下鉴定显示研究区发育溶解作用、去白云化作用、压溶作用、破裂作用4种主要的建设性成岩作用和泥晶化作用、压实作用、胶结作用、白云化作用、硅化作用、重结晶作用6种主要的破坏性成岩作用。结合C-O同位素分析结果,本区存在海底（浅海台地和深水斜坡）、大气淡水（渗流带和潜流带）和埋藏等3种主要的成岩环境,分别发育不同的成岩作用,海底环境：主要为泥晶化作用（浅海台地）和第一类硅化作用（深水斜坡）;埋藏环境：主要为压实作用、压溶作用、白云化作用、第三类选择性硅化作用和晚期重结晶作用;大气淡水环境：胶结作用（潜流带粒状等厚环边胶结物、粒状胶结物和共轴增生胶结物,渗流带重力型胶结物和新月型胶结物）、溶解作用、早期重结晶作用、去白云化作用和第二类硅化作用。研究区除了含有较高的有机质外,还发育较高的孔隙度,最高可达2%~5%,主要集中在船山组和栖霞组的压溶线内及栖霞组硅质层和富硅质灰岩段,孔隙连通性极好,而且线内常含有大量有机质,是油气生成、储集和运移的理想场所。因此,安徽无为—巢湖地区中下二叠统碳酸盐岩成岩作用的研究对本区地质工作的深入、油气资源的预测与勘探都具有重要的理论和战略意义。
Diagenesis controls the porosity evolution,which is of great indicative importance for the exploration of the oil and gas.The Middle-Lower Permian carbonate in the Wuwei-Chaohui area,Anhui Province,is well developed and widely distributed with abundant organic materials.Years＇ studies have focused only on strata,paleontology and sedimentary facies,but little on diagenesis.Microscopic examination shows that there are four major destructive diageneses such as dissolution,dedolomitization,pressure solution,and tectonic rupture,and six types of constructive diaenesis namely micritization,compaction,cementation,dolomitization,silicification,and recrystallization developed in the studying area.Combined with the C-O isotope analysis results,this area has three main diagenetic environments such as marine（shallow marine platform and deep sea slope）,meteoric（vadose and phreatic zone）,and burial,which response to different diagenesese.Micritization（shallow marine platform） and the first type of silicification（deep sea slope） occurs in marine environment;burial environment contains mainly compaction,pressure solution,dolomitization,the third type of selective silification and late recrystallization;meteoric environment develops cementation（including drusy isopachous rim cement,drusy cement and coaxial accretion cement,belonging to phreatic zone,gravity-type cement and crescent cement,belonging to vadose zone）,dissolution,early recrystallization,dedolomitization and the second type of silicification.Along with rich organic matters,the studying area has high porosity,up to 2%~5%,and mainly developed in the pressure solution of Chuanshan and Qixia Formations,and in the silicon members and silicon highly contained limestone of Qixia Formation.Excellent connectivity and rich organic matter make it the ideal place for generation,storage and migration of the gas and oil.Therefore,this study is of great theoretical and strategical significance for the further geological study and prediction and exploration of the gas and oil in Anhui Province.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2011年第4期543-556,共14页
Acta Geologica Sinica
基金
安徽省自然科学基金项目(编号070415205)
国家自然科学基金项目(编号40972082
40572076)
中国石油化工股份有限公司项目(中上扬子及邻区古生代古沉积环境演化研究)联合资助成果
