川西坳陷新场气田上三叠统须家河组须四上段沉积微相研究

Sedimentary Microfacies of Upper Xu 4 Submember of Upper Triassic in the Xinchang Gas Field of West Sichuan Depression

综合新场地区33口钻井须四上亚段的73个岩心标本及221块岩石薄片等资料,运用沉积学和层序地层学理论方法,从岩石特征、沉积构造、测井相及地震相等方面详细分析了川西坳陷新场气田须家河四段上亚段X44,X43,X42三个砂层组的沉积微相展布及特征。结果表明,研究区须四上亚段为三角洲沉积三角洲前缘亚相,包括水下分流河道、分流间湾、天然堤、河口坝四种沉积微相,X44,X43,X42各小层的沉积微相展布显示出退积-进积的沉积过程,储集性砂体主要分布于水下分流河道微相中。

This paper integrated 73 core specimens,221 petrographic thin sections and other information of upper sub- member of Xu 4 of 33 well drillings in Xinchang area, and by utilizing the sedimentology and sequence stratigraphy theory methods,analyzed the sedimentary microfacies and features of X_4^4,X_4^3,X_4^2from rock characteristics, sedi mentary struetures,electrofacies,earthquakes and other aspects in detail of three sand groups in upper submember of Xu 4, Xinchang gas field. Results show that,the of Xu 4 is delta front,including underwater distributary river chan- nels,interdistributary bay,nature levee and mouth bar. With the sedimentary microfacies of every small stratum in upper submemher of Xu 4 ultimately determined, each sedimentary microfacies of small stratum in X_4^4,X_4^3,X_4^2 shows a retrograding - prograding sequence of the deposition process, and reservoir sand body is mainly distributed in the microfacies of underwater distrihutary river channels.