塔里木盆地塔中隆起北坡鹰山组白云岩储层特征与成因

塔里木盆地塔中隆起北坡奥陶系鹰山组目前勘探发现的丰富油气资源主要蕴藏在石灰岩岩溶缝洞型储层中,这类储层受鹰山组顶部不整合面的控制。随着勘探的深入,部分探井揭示了鹰山组白云岩储层类型,其储集空间为晶间孔、超大溶孔和溶洞,部分井段物性好且厚度较大,但横向对比性差。通过岩心、薄片观察、阴极发光、稀土元素及同位素等实验分析,认为鹰山组优质白云岩储层经历了埋藏白云石化和较强溶蚀作用,后期又受到高温流体的影响。鹰山组优质白云岩储层分布面积大,其发育主要受控于地下流体活动,是塔中隆起北坡鹰山组碳酸盐岩储层的重要类型和勘探领域。 

Characteristics and origin of dolomite reservoirs in Lower Ordovician Yingshan Formation, northern slope of Tazhong uplift, Tarim Basin

At present, the rich oil-and-gas resources discovered in the Ordovician Yingshan Formation in the northern slope of the Tazhong uplift of the Tarim Basin mainly exist in limestone karst fracture-cave reservoirs which are controlled by the unconformities on the top of the Yingshan Formation. With the deepening of exploration, dolomite reservoirs in the Yingshan Formation have been found in some new exploratory wells, and the reservoir spaces mainly include intercrystal pores, solution pores and vugs. Dolomite reservoirs have good physical properties and are thick locally; however, their horizontal comparisons are poor. According to core, slice observation, cathodoluminescence, REE and isotopic analyses, the favorable dolomite reservoirs in the Yingshan Formation had experienced buried dolomitization and strong dissolution, and was influenced by hot fluid in the late stage. Distributed widely and controlled by underground fluid activities, the dolomite reservoirs are the key types and targets for explorations in carbonate reservoirs in the Yingshan Formation in the northern slope of the Tazhong uplift of the Tarim Basin.