北布扎奇油田下白垩统三角洲前缘砂体构型及剩余油分布模式

Delta front reservoir architecture characterization of Lower Cretaceous and remaining oil distribution patterns in North Buzachi Oilfield

北布扎奇油田下白垩统三角洲前缘储层是主要的开发层位,内部结构复杂。利用岩心、测井、地震及动态监测等资料,进行微相复合体及单一微相构型表征,建立构型控制下的剩余油分布模式。结果表明:北布扎奇油田下白垩统三角洲前缘主要发育坝主体拼接连片河口坝与分流河道、坝缘拼接河口坝与分流河道、孤立河口坝与分流河道和孤立滩砂4种微相复合体平面分布样式,以及单一分流河道和河口坝的拼接样式、单一河口坝之间的拼接样式两大类,主干分流河道-河口坝拼接、末端分流河道-河口坝拼接、坝主体-坝主体拼接、坝缘-坝缘拼接、河口坝-坝间泥-河口坝拼接5种单层优势微相样式。受构型的影响,注入水沿分流河道平面舌进、侧向隔挡体和坝缘侧向阻碍、不稳定层间隔层、层间干扰分别在河口坝、坝主体边部、河口坝边部、上部砂体、相对低渗层发生剩余油富集。该结果对相似油田的剩余油挖潜具有一定指导意义。

Delta front reservoir of the Lower Cretaceous is the main reservoir in North Buzachi,Kazakhstan.The study of delta front architecture characterization is the key to tapping the potential of remaining oil.According to the data from rock cores,well logging and seismic interpretations and production data,this thesis studied the architecture characteristic by different hierarchy(microfacies combination and single microfacies).The research results show that delta front mainly develops distributary channel,mouth bar(bar body and bar edge),beach sand,mudstone between the mouth bars et al.The patterns of dominant mocrofacies distribution in monolayer include continuous mouth bar,partly continuous mouth bar,isolated mouth bar and isolated beach sand.There are two lateral splicing types,single distributary channel and mouth bar,mouth bar and mouth bar.It includes five splicing types of single microfacies(trunk distributary channel and mouth bar contact,terminal distributary channel and mouth bar contact,bar bodies contact,bar edges contact,mudstone and mouth bars contact).Study area consists of the following five kinds of remaining oil distribution pattern controlled by flow barriers and differences:unstable interlayer results in scurrying layer and oil remain in upper sand body;lateral barrier body leads to oil remaining bar edge;interlayer interference results in oil remaining in relatively low permeability layer;injected water flow along the distributary channel causing plane fingering and remaining oil enrichment in mouth bar;bar edges lateral hinder leads to remaining oil enrichment in marge of bar body.This study provides a certain guiding significance for the exploitation of residual oil in similar oilfields.