高尚堡油田砂质辫状河储集层构型与剩余油分布

Architecture and remaining oil distribution of the sandy braided river reservoir in the Gaoshangpu Oilfield

以洪泛期沉积的泥岩作为标志层,应用精细成因地层对比方法建立南堡凹陷高尚堡油田新近系馆陶组下段辫状河单砂层成因地层格架。将辫状河地质露头及室内沉积模拟实验成果作为模式指导,通过辫状河单河道识别、地质统计学规律和生产监测资料分析,确定该区辫状河单河道宽140～560 m。根据岩相组合类型及其顶底界面特征,识别出河道充填、顺流增生、砂质底形、砂席和溢岸细粒等5类辫状河储集层构型单元。河道充填构型单元发育和优势渗流通道导致河道充填构型单元形成底水水锥型水淹,剩余油分布在油井间且丰度高。顺流增生单元纵向渗透率级差小,水淹均匀,剩余油呈薄层状低丰度分布在油井间。

With mudstone deposited in the flooding period as the marker horizon and based on fine correlation for reservoir genesis,the stratigraphic framework in braided river single sand bed of the lower member of the Neogene Guantao Formation in the Gaoshangpu Oilfield of the Nanpu Sag is established.Guided by braided river geologic outcrops and sedimentary simulation results,based on identification of braided river single river channel,rules of geostatistics and production monitoring data analysis,the width of braided river single river channel in this area is determined as 140-560 m.According to the analysis on lithofacies associations and features of base and top surfaces,five architectural elements for braided river reservoirs are identified,i.e.channel filling,downstream accretion,sandy bed form,sand sheet and overbank fines.For channel filling architectural element,lithofacies association of Se-St-Sh-Sm in normal rhythm is developed,with large vertical permeability difference and high oil-water viscosity ratio.Dominant flow pathways emerge at high fluid production rate.Due to high fluid production rate and dominant flow pathways,water coning flooded oil zone will be generated in channel element,which leads to high abundance oil remaining between wells.The downstream accretion element is featured by small vertical permeability difference and uniform water flooding,so thin-layered remaining oil is distributed between oil wells with low abundance.