珠江口盆地惠州凹陷深部古近系储层特征及发育控制因素

Characteristics and Development Controlling Factors of Paleogene Deep Reservoirs in Huizhou Depression,Pearl River Mouth Basin

惠州凹陷古近系自下而上依次发育文昌组、恩平组及珠海组,深部储层主要发育在恩平组和珠海组。储层的孔隙类型包括粒间溶孔、粒内溶孔、黏土矿物微孔等次生孔隙,同时还含有剩余原生粒间孔和裂缝。其中,原生孔隙度平均为2.4%,占总孔隙度的22.2%;次生孔隙度为5.6%,占总孔隙度的65.2%;裂缝孔隙度为1.0%,占总孔隙度的12.5%。深层岩样的平均面孔率在9.1%。次生孔隙的发育大大提高了深层砂岩的储集性能,其成因主要是有机酸对砂岩骨架颗粒和基质组分的溶解作用。有机酸参与的溶蚀作用是储层的主要建设性成岩作用,长石含量的多少直接影响着次生孔隙的发育程度。次生孔隙发育带深度范围主要为3500～4200m,物性相对较好;4200～4500m仍以发育次生孔隙为主,但由于晚期的再胶结和压实作用,孔隙度总体明显下降。恩平组储层主要发育在水下分流河道上,珠海组储层主要发育在三角洲平原的分流河道、三角洲前缘的水下分流河道—河口坝及滨岸砂体。

The Paleogene strata are constituted of Wenchang,Enping and Zhuhai Formations in Huizhou Depression.Deep reservoirs are in Enping and Zhuhai Formations.The reservoirs mainly consist of secondary porosity such as intergranular and intragranular dissolved pores,and clay mineral micropores as well as residual primary intergranular pores and fissures,among which the average primary porosity is 2.4%（accounting for 22.2% of the total porosity）,the average secondary porosity is 5.6%（65.2% of the total） and the average fissure porosity is 1.0%（12.5% of the total）.Development of secondary porosity improved the reservoir capacity of deep sandstone due to dissolution of organic acid to skeleton grains and matrix in sandstone.The secondary porosity developed well in a depth range of 3500～4200m where reservoir property is good but the secondary porosity is obviously decreased in the depth of 4200～4500m due to the late recementation and compaction.argin but TypeⅡand TypeⅢ in the Northwest Shelf of Australia,Mid-Norway continental shelf and South Sea.