饶阳凹陷大王庄地区沙一上亚段河口坝结构对油藏开发的影响

Influence of estuary bar structure on reservoir exploitation of upper Sha-1 submember in Dawangzhuang area,Raoyang Sag

饶阳凹陷大王庄地区沙一上亚段Ⅲ,Ⅳ油组发育水下分流河道与河口坝砂体,其内部结构影响着油藏的开发,但该区河口坝内部结构和隔夹层的分布情况缺乏系统的研究。利用岩心资料、测井数据、生产数据等多种资料,在识别和分析沉积微相的基础上,对河口坝、泥质隔夹层的结构特征及油藏特征进行解剖,明确了河口坝的内部结构对油藏开发的影响,建立了油藏模式。结果表明:大王庄地区沙一上亚段Ⅲ,Ⅳ油组发育三角洲前缘亚相,包括水下分流河道、河口坝和水下分流间湾3种微相。不同期河口坝之间和同一期河口坝内部发育泥质隔夹层。在顺物源方向上,河口坝呈S型叠置前积;在垂直物源方向上,多期河口坝纵向上叠置堆积;河口坝间发育泥质隔层,单个河口坝内部发育泥质夹层。研究区一共发育3种类型的油藏:断层控制油藏、岩性控制油藏、断层-岩性复合油藏。不同期次河口坝间的泥质隔层作为油气的隔挡,是造成油水界面不统一的原因,而河口坝内部的夹层厚度较薄,规模小,不影响连通性。

Underwater distributary channels and estuary bar sandbodies were developed in the third and fourth oil members of the upper Sha 1 member(Es1)in Dawangzhuang area of Raoyang Sag,and their internal structure influences the development of reservoirs.However,there is a lack of systematic research on the internal structure of estuary bar and the distribution of interbeds in this area.Based on the identification and analysis of sedimentary microfacies,the structural characteristics and reservoir characteristics of estuary bars and muddy interbeds were dissected by using core data,logging and production data.The influence of the internal structure of estuary bars on reservoir development was clarified and the reservoir model was established.The results show that in the third and fourth oil groups of upper Es1 in Dawangzhuang area,delta front subfacies was developed,including three microfacies:underwater distributary channel,estuary bar and underwater distributary bay.Muddy interbeds were developed between and within estuary bars.Along the source direction,estuary bar was S-shaped superimposed pre-accumulation,while in the vertical source direction,the multi-stage estuary bar was stacked vertically.The muddy barriers were developed between the estuary bars,and muddy interbeds were developed within the single estuary bar.There are three types of reservoirs developed in the study area:fault-controlled reservoir,lithology-controlled reservoir and fault-lithology composite reservoir.The muddy barriers between estuary bars in different stages are the reason for the inconsistency of oil-water interface,while the muddy interbeds within estuary bars are thin and the scale is small,which does not affect the connectivity.