白云石化对储层发育的控制作用——以普光、元坝气田飞仙关组为例

Control effect of dolomitization on reservoir development: taking Feixianguan Formation in Puguang and Yanba gas fields for example

厚东琳

HOU Donglin

中国石化勘探分公司，四川 成都 610041

SINOPEC Exploration Company, Chengdu 610041, China

普光气田和元坝气田飞仙关组均发育一套鲕粒碳酸盐岩储层，不同的是普光气田为鲕粒云岩而元坝气田为鲕粒灰岩，同时前者在储层物性上比后者高出了1个数量级左右。通过岩心、薄片观察，结合地球化学分析等测试手段，对造成该现象的原因进行深入分析。结果表明：普光气田鲕滩云岩碳、氧同位素特征与原始海相灰岩一致，而锶同位素略高于同期海水变化范围，说明普光气田飞仙关组鲕粒云岩属于早期低温白云石化范畴；普光气田由于经历了早期白云石化，其储层孔喉结构得到了优化，为暴露溶蚀流体提供了大量的渗滤通道，因而，相对于元坝气田，形成了更为多样化的储渗空间，最终形成了更为优质的储层。

The oolitic carbonate reservoir is developed in the Triassic Feixianguang Formation, Puguang and Yuanba gas fields. The reservoir in Puguang gas field is oolitic dolomite; however, the reservoir in Yuanba gas field is oolitic limestone. The petrophysical of Puguang gas field has an order of magnitude higher than the petrophysical of Yuanba gas field. This article combines the core and thin section observation with the geochemistry analysis to explain the phenomenon. The result shows that the characteristics of carbonate and oxygen isotopes in Puguang gas field is according with the primary marine limestone, while the strontium isotope is little higher than the average level of the sea water in the same time, which shows the oolitic dolomite in Puguang gas field belongs to early dolomitization category; on the account of the early dolomitization, the pore structure in the reservoir in Puguang gas field was optimized, which provided a good flow passage for the dissolution fluid and finally formed diversified pores leading to a better petrophysical properties compared with the Yuanba gas field.

10.6056/dkyqt201904009