塔河油田石炭系三角洲微地震相研究

Analysis of micro-seismic facies in delta of Carboniferous formation at Tahe oilfield

塔河油田石炭系油藏是一个具有中低渗透率的三角洲沉积环境的岩性油藏，有效砂体厚度较薄，单砂体相互叠置，厚度变化较大（3～15m），储层物性变化大，非均质性强，勘探难度较大。针对这些问题，在塔河油田四区石炭系卡拉沙依组开展了微地震相研究。对石炭系卡拉沙依组的地质与地球物理特征进行了分析，在此基础上，利用神经网络技术，对卡拉沙依组顶面（E）和三角洲前积层等时界面进行了微地震相分析。采用对地震道进行逐道对比分类的方法，细致刻画了地震波形的横向变化特征，并结合测井相解释和地质背景分析结果，对研究区的沉积相进行了解释。在该区，分布有沉积三角洲平原、前缘亚相以及分流河道、水下分流河道、河口砂坝、泛滥平原等沉积微相，解释结果与钻井和生产测试结果相符合。

Carboniferous oil pool in Tahe oilfield is a litholngic deposit with middle-low permeability of delta sedimentary environment. The sand bodies of the oil pool are superposed with the effective thickness being relatively thin and changing in a wide interval (3～15m).In addition,it is quite heterogeneous and so is not stable in physical property.All these make the exploration be very difficult. Aimed at these problems,the micro-seismic facies analysis is car- ried out to the Kalashayi formation of Carboniferous in Tahe No.4 oilfieid.Based on the study of geological and geophysical character- izations of the formation,the micro-seismic facies of the top hori- zon (T_5~0) of the Kalashayi formation and the isochronal interface of delta forest bed are analyzed by the neural network algorithm. Through contrasting seismic traces one by one and classifying them,the horizontal changes of seismic waveforms are character- ized and the sedimentary environment of target zone is interpreted according to the results of tog sedimentary facies and geological in- formation.Many microfacies are distributed in the area,such as delta plain,delta front,distributary channel,submarine distribu- tary channel,river mouth bar,and flood plain.The interpretation results are well matched with the drilling and production test data.