海上稀井网油田碎屑岩储集层构型特征及储集层预测——以珠江口盆地陆丰凹陷L14油田为例

Architecture and Prediction of Clastic Reservoirs in Offshore Oilfields With Sparse Well Pattern:A Case Study on L14 Oilfield in Lufeng Sag in Pearl River Mouth Basin

针对海上油田井距大、井网稀、储集层非均质性强等特征,以珠江口盆地陆丰凹陷L14油田古近系文昌组文五段为例,提出“层次约束、分级解剖、模式拟合、井震互馈、多维联动”的陆相辫状河三角洲储集层构型表征方法,运用分频RGB融合技术,表征储集层构型单元,并在储集层构型划分的基础上,预测优质储集层。结果表明,研究区三级构型单元为复合分流砂坝,四级构型单元为分流砂坝、分流河道和辫状河道;四级构型单元具有3种垂向叠置样式和2种侧向拼接样式;岩石矿物组分和构型单元对物性起主导作用;文五段以Ⅰ类储集层为主,多分布在分流砂坝内部;Ⅱ类储集层主要分布在Ⅰ类储集层的外缘,连续性较差;Ⅲ类储集层通常与Ⅱ类储集层伴生,连续性最差;由分流砂坝中心向分流砂坝外缘,再到分流砂坝间的分流河道和辫状河道,储集层品质逐渐降低。

Offshore oilfields are characterized by large well spacing,sparse well pattern,and strong reservoir heterogeneity.Taking the 5th member of Wenchang formation(Wen 5 member)of Paleogene in L14 oilfield,Lufeng sag,Pearl River Mouth basin,as an example,a method for characterizing the architectures of continental braided river delta reservoirs based on“hierarchy constraint,subdivided dissection,pattern fitting,logging-seismic cross-feedback and multidimensional coordination”was proposed.By using frequency-dividing RGB fusion technology,the architecture units of the reservoirs were characterized.On the basis of reservoir architecture division,high-quality reservoirs were predicted.The results show that the third-order architecture unit in the study area is composite distributary bar,and the fourth-order architecture unit is composed of distributary bar,distributary channel and braided channel.The fourth-order architecture unit is found with three vertical stacking styles and two lateral splicing styles.The rock mineral components and architecture units play a leading role on physical properties.In the Wen 5 member,ClassⅠreservoirs are dominant and mostly distributed in distributary bars;ClassⅡreservoirs are mainly distributed in the outer edge of ClassⅠreservoirs,with poor continuity;and ClassⅢreservoirs are often associated with Class II reservoirs,with the poorest continuity.From the center to the outer edge of the distributary bar,and then to the distributary channel and braided channel between the distributary bars,the reservoir quality gradually decreases.