莺歌海盆地XF区黄流组砂岩储集性能差异的控制因素及其地质意义

Controlling factors of storage capacity differences of Huangliu Fm sandstone in XF area of the Yinggehai Basin and their geologic significance

XF区位于莺歌海盆地中北部底辟带上,近期在其中深层(上中新统黄流组)勘探中相继发现了XF13-1、XF13-2大型岩性+构造复合型气田。为弄清中深层天然气主力产层的物源方向,以指导气田下一步的勘探部署,根据碎屑组分特征、重矿物组合特征,结合沉积相分析,综合判断该区黄流组一段的主要物源方向为:XF13-1气田西部、XF 13-2气田、XF 29-1构造西部的海底扇水道砂源于西部昆嵩隆起物源区;而XF 13-1气田东部、XF 29-1构造东部以及XF 1-1气田的浅海滩坝砂主要源于东部海南岛隆起物源区。结论认为:物源体系影响了该区沉积体系的空间布局和储层品质,受此影响,相对高渗储层主要分布在源于西部昆嵩隆起物源区的海底扇水道砂岩体中,水道砂岩体储层规模大(单层厚度大多超过10m,最大单层厚度可达91.2m,分布广,延伸至XF1-1底辟构造西侧,并具有多期次发育的特征),储集性能良好,构成了XF13-1、XF13-2气田主力储层;水道砂岩体也是该区下一步天然气勘探的主攻方向和目标。

Two large composite lithologic and structural gas fields, namely XF 13-1 and XF 13-2, were discovered successively in the medium to deep horizons （the Upper Miocene Huangliu Fm） in XF area located on the diapir zone in the north-central Yinggehai Basin. In order to identify the provenance of the major pay zones and guide future exploration, we performed a comprehensive study of the detrital components, heavy mineral assemblage and sedimentary facies. The submarine fan channel sands in the western part of XF 13-1 gas field, XF 13-2 gas field and the western part of XF 29-1 structure were sourced from the provenance on the western Kumtom uplift. In contrast, the shallow marine beach bar sands in the eastern part of XF 13 1 gas field, the eastern part of XF 29- 1 structure and XF 1-1 gas field came from the provenance on the Hainan Island to the east. The provenance systems influenced the spatial distribution of sedimentary systems and reservoir quality. The reservoirs with relatively high permeability are mainly distributed in the submarine fan channel sands sourced from the provenance on the western Kumtom uplift. The channel sandstone reservoirs are large in scale （single layer thickness mostly over 10 m and maximum up to 91.2 m, being extensive in distribution and extending to the west of XF 1-1 diapir structure, multiple stage development） and high in quality. They constitute the major reservoirs of XF 13-1 and XF 13-2 gas fields. The channel sands are major targets for future gas exploration in this area.