苏北盆地东南部泰州组砂岩储层孔隙类型及有利储层评价

利用50余口井的储层实验资料,对苏北盆地主力勘探地区海安凹陷和高邮凹陷泰州组砂岩储层进行孔隙类型和有利储层评价。综合研究表明：海安凹陷和高邮凹陷泰州组发育三角洲、浊积扇、扇三角洲等成因类型砂体,这些砂体由成分和结构成熟度较低的长石岩屑砂岩和岩屑长石砂岩组成,并且砂岩储层发育次生孔隙,原生孔隙较少;海安凹陷泰州组储层第一个次生孔隙发育段为2 300～2 500m,系大量碳酸盐胶结物、长石和岩屑颗粒遭受强烈溶蚀而成,孔隙度为12%～25%,第二个次生孔隙发育段为2 600～3 200m;高邮凹陷泰州组储层孔隙演化与海安凹陷有一定差异,其只存在1个次生孔隙发育段（2 400～2 900m）,孔隙发育程度与海安凹陷的第一个次生孔隙带相似;泰州组砂岩储层中次生孔隙的形成主要与沉积物中有机质演化产生的有机酸、酚以及碳酸有关;大部分次生孔隙是由粒间碳酸盐胶结物溶蚀产生;海安凹陷有利储层主要分布在西北部和东部三角洲前缘砂体和滑塌浊积扇砂体中,高邮凹陷有利储层主要分布在南部扇三角洲前缘砂体中,储层埋藏浅、物性好,均以Ⅰ和Ⅱ类储层为主,是有利的勘探地区。

Pore Types of Sandstone Reservoir and Evaluation of Favorable Reservoir of Taizhou Formation in Eastern Subei Basin

The pore types of sandstone reservoir and evaluation of favorable reservoir of Taizhou Formation of Haian and Gaoyou Depressions,which are the key regions in Subei Basin,were studied according to the reservoir analytical data from more than 50 wells.The results showed that the sandbodies of delta,turbidite fan and fan-delta,which were composed of feldspatite debris sandstone and rock debris arkose with low maturity of content and texture,were developed,and there were many secondary pores and little primary pores in sanstone reservoir of Taizhou Formation of Haian and Gaoyou Depressions;the first secondary pore zone located in the depth of 2 300-2 500 m in Taizhou Formation of Haian Depression,because many carbonate cement,feldspar and debris dissolved obviously,the porosities of sandstones were 12%-25%,and the second secondary pore zone located in the depth of 2 600-3 200 m;it was different of pore evolution of reservoir in Taizhou Formation between Haian and Gaoyou Depressions,because there was only one secondary pore zone（2 400-2 900 m） in Gaoyou Depression and the porosity of sandstone was similar to that in Haian Depression;the formation of secondary pore of sandstone reservoir in Taizhou Formation was controlled by organic acid,phenol and carbonic acid during the organic evolution;most secondary pores were produced by the dissolution of intergranular carbonate cements;the favorable reservoir in Haian Depression distributed in northwestern and eastern delta front sandstone and turbidite fan sandstone,and the favorable reservoir in Gaoyou Depression distributed in southern fan-delta front sandstone;physical properties of all the favorable reservoirs were good,and the depths of burial were shallow,so the reservoirs were favorable areas for the further exploration.