乌石凹陷东区流三段层序地层与沉积演化

Sequence Stratigraphy and Evolution of The 3rd Member of Liushagang Formation in Eastern Wushi Depression

北部湾盆地乌石凹陷东区流三段油气资源规模巨大,以高分辨率层序地层学和沉积学为理论指导,对岩壁心、测井和地震等资料进行分析研究,在流三段划分了2长期旋回、5个中期旋回,建立了相应的等时层序格架;通过对岩性特征、沉积构造、岩石颗粒粒度和地震反射特征等方面系统分析表明流三段为扇三角洲沉积,可细分为扇三角洲平原和前缘亚相,物源来自北东方向;在流三段沉积早期扇三角洲平原面积大,到了中晚期扇三角洲平原面积逐步减小,并从基准面旋回的角度探讨了层序格架内储层沉积特征和演化规律,总结了其沉积模式。

Based on the analysis of the data of well logging,core and seismic data,combining with application of high resolution sequence stratigraphy and the modern sedimentological theory,two longterm base level cycle and five medium-term base level cycles were divided,isochronous sequence stratigraphic framework was established in the 3 rd Member of Liushagang Formation of B oilfield,eastern Wushi depression. Fan delta was identified,including fan delta plain and fan delta front,according to the analysis of lithologic features, sedimentary structures, rock particle size and seismic reflection characteristics of L3,whose provenance is from the northeast. The distribution of fan delta plain was widespread in the early sedimentary stage of L3,while it shrinked gradually as the time came to the middle and late sedimentary stage of L3. The reservoir sedimentary characteristics and evolution in the sequence stratigraphic framework was discussed from the aspect of base level cycle,what ’s more,sedimentary model was summarized.