北海北部盆地布伦特群的沉积储层特征
DEPOSITIONAL CHARACTERISTICS OF THE RESERVOIR IN BRENT GROUP, NORTH SEA BASIN
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摘要: 以北阿尔文及其邻近油田为研究对象,通过对岩心、测井及成岩过程等资料的分析,探讨了布伦特群的储层特征。北海盆地布伦特群从南到北依次发育海岸平原相—河口坝/上临滨—远砂坝/下临滨—近海相沉积,布伦特群下属的布鲁姆组和塔伯特组均为海进期潮控砂岩,而兰诺奇组、埃蒂夫组和内斯组则为进积三角洲沉积。布伦特群可划分为4个层序,均由水进体系域和高位体系域组成,其中塔伯特组自古至新可以进一步分为塔伯特1、塔伯特2和塔伯特3等3个单元,内斯组可分为内斯1和内斯2两个单元。布伦特群储层物性受控于沉积相带和成岩作用,布伦特群最优质的储层为三角洲(海岸)平原相分流河道砂,成岩作用对储层的影响主要体现在隆升成岩期对孔隙的保存及深埋成岩期对储层的破坏2个方面。Abstract: The reservoirs in the Brent Group were studied in this paper, based on core,well logging and diagenetic data. The facies distribution of the Brent Group show a pattern from coastal plain-proximal delta-mouth bar/upper shoreface-distal delta-mouth bar/lower shoreface-offshore marine from south to north. The Broom and the Tarbert Formations are transgressive, tide influenced deposits, while the Rannoch, Etive and Ness Formations are progradational deltaic deposits. There are four sequences in the Brent Group. Each of them is composed of transgressive systems tract and high systems tract. According to sequence stratigraphical analysis, the Tarbert Formation is divided into three units (Tarbert 1, 2 and 3), while the Ness Formation consists of two (Ness 1 and 2). Reservoir properties are controlled by both depositional facies and diagenetic events. High quality reservoirs are mainly formed in deltaic, costal plain environments and distributary channels. Diagenetic events effect reservoir properties either in a constructive way as the uplift-related diagenesis or in a destructive way as the burial diagenesis.