上扬子地区下寒武统黑色页岩矿物组成特征及其油气勘探意义

发布时间：2018-04-22 17:41

本文选题：上扬子地区 + 早寒武世　；参考：《天然气工业》2017年04期

【摘要】：下寒武统是上扬子地区海相页岩气藏的重要勘探层系之一,但受目的层埋藏深、钻井少、勘探效果不理想等因素的制约,尚存在着诸多影响勘探进展的地质问题。为此,基于X射线衍射、岩石薄片、普通扫描电镜及氩离子抛光—扫描电镜等资料,分析了该区下寒武统黑色页岩的矿物组成特征及其油气勘探意义。结果表明:①该区页岩组成以黏土矿物和石英为主,其次为碳酸盐矿物及长石,其中石英平均含量为44.60%,发育陆源石英和生物成因硅质2种类型,而黏土矿物平均含量为33.32%,以伊利石(I)含量最高、伊/蒙混层(I/S)含量不均且混层比低(一般为5%)、局部含绿泥石(C)及高岭石(K)为特征;②从该区页岩中可识别出I+I/S+C型、I+I/S+C~I+C过渡型、I+C型及I型4种黏土矿物组合类型,指示不同地区页岩成岩环境存在着差异;③矿物颗(晶)粒无序排列有利于粒间孔隙残存,长石向黏土矿物成岩蚀变可形成线状孔隙;④该区页岩的脆性指数一般都超过40%,具有良好的可压裂性,黔东南地区与川西南地区相比前者页岩脆性更好。
[Abstract]:The Lower Cambrian is one of the important exploration strata of marine shale gas reservoirs in Upper Yangtze area, but there are still many geological problems which affect the progress of exploration due to the factors of deep burial of the target layer, less drilling and unsatisfactory exploration effect. Based on the data of X-ray diffraction, thin rock slice, general scanning electron microscope and argon ion polishing scanning electron microscope, the mineral composition characteristics and hydrocarbon exploration significance of the lower Cambrian black shale in this area are analyzed. The results show that the shales in the area are mainly composed of clay and quartz, followed by carbonate minerals and feldspar, in which the average content of quartz is 44.60. There are two types of terrestrial quartz and biogenic siliceous. The average mineral content of clay is 33.32, with Illite content being the highest, and the content of I / S in the mixed layer is uneven and the mixing layer ratio is low (generally 5%, with local content of chlorite) and kaolinite (K). (2) four types of clay mineral assemblages, I / I / S / C, I / I / C transition type and I type I, are identified from the shale in this area, indicating that there are differences in the diagenetic environment of shale in different regions. (3) the disordered arrangement of mineral grains (grains) is favorable to the residual of intergranular pores. The brittle index of shale in this area is generally more than 40, which shows good fracturing ability. The diagenetic alteration of feldspar to clay minerals can form linear pores. The shale brittleness of Qiandongnan is better than that of southwest Sichuan.
【作者单位】：页岩油气富集机理与有效开发国家重点实验室;中国石化页岩油气勘探开发重点实验室;中国石化石油勘探开发研究院;中国石油大学(北京)理学院数学系;
【基金】：国家自然科学基金项目“高热演化条件下页岩气聚集机理和评价方法研究”(编号:41202103) 国家科技重大专项“彭水地区常压页岩气勘探开发示范工程”(编号:2016ZX05061) 中国石油化工股份有限公司科技开发部项目“中上扬子下寒武统页岩气甜点区研究”(编号:P15114)
【分类号】：P618.13

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