先把扎工区石炭系小海子组层序划分及沉积特征

Sequence Division and Depositional Characteristics of the Carboniferous Xiaohaizi Formation in Xianbazha Area

采用地层旋回分析法开展先把扎工区石炭系小海子组层序格架研究,选择工区关键井进行层序划分,建立石炭系小海子组精细层序格架。在层序研究的基础上开展沉积相研究,通过巴探4井、巴探7井等钻井的层序分析,石炭系小海子组可划分出两个层序:CSQ5(小海子组下段)、CSQ6(小海子组上段)。CSQ5为低可容纳空间环境下发育的层序,为B型层序;CSQ6为高可容纳空间环境下发育的层序,为A型层序。以单井沉积相、连井剖面及沉积相平面展布分析为基础,结合地震、钻井等其他资料分析认为,工区石炭系小海子组发育开阔台地相,进一步划分为台滩和滩间海亚相,CSQ5主要发育台滩、滩间海亚相;CSQ6主要发育滩间海亚相,台滩亚相是先巴扎工区储层的有利发育相带。

A stratigraphic cyclic analytical method was used for researching the sequence stratigraphic framework of Carboniferous Xiaohaizi Formation in Xianbazha Area,the key wells of the studied area were chosen for sequence stratigraphic division and establishing fine sequence stratigraphic framework of the Carboniferous Xiaohaizi Formation.On the basis of studying the sequence stratigraphy,sedimentary facies was studied.Through analyzing sequence of Exploration Well Ba 4and Well Ba 7,it was indicated that the Carboniferous Xiaohaizi Formation could be divided into two sequences:such as CSQ5(the lower member of Xiaohaizi Formation),CSQ6(the upper member of Xiaohaizi Formation).The sequence CSQ5was the sequence which was developed in low accommodation space environment,it was a Type B sequence.Sequence CSQ6was a sequence which was developed in high accommodation space environment,it was a Type A sequence.The single well sedimentary facies,cross sections and the plane distribution of sedimentary facies are the basis of analysis,combined with seismic,drilling and other data,it is considered that the Carboniferous Xiaohaizi Formation develops open platform facies,it is further divided into beach and beach between sea subfacies,CSQ5mainly develops beach and beach between sea subfacies;CSQ6mainly develops beach between sea subfacies,beach facies is the beneficial development facies belt of the reservoir in Xianbazha Area.