关键词: 阜康凹陷, 头屯河组, 敏感性, 自生石英, 控制因素

Abstract:

The Toutunhe Formation in Fukang Sag, Junggar Basin, is mainly characterized by low porosity and low permeability with many types of fillers and complex pore structures. But there is a serious contradiction between the potential acid sensitivity damage and the indoor evaluation, and the variability exists in the sensitivity of the reservoir. Therefore, the reservoir sensitivity evaluation and control factors are studied by the core experiments such as core displacement, casting thin section identification, nuclear magnetic resonance, scanning electron microscope, etc. The results show that in Toutunhe Formation, the velocity sensitivity is weak, the water sensitivity and salt sensitivity are both upper medium to strong, the alkali sensitivity is upper medium, and the acid sensitivity is weak to moderate weak. The difference of reservoir sensitivity is related to many types of interstitial fillers and complex pore structures. In the Toutunhe Formation reservoir enriched with the cement of authigenic quartz, whose diameter is less than 5 μm, the corrosion of the surface clay by the acid-base liquid lead to the exfoliation of the crystals such as the authigenic quartz. Then, these movable particles obstruct the pore throat. The mechanism of this kind of damage which shows a upper medium to strong acid sensitivity is different from that of the other traditional damage such as the secondary precipitation. The sensitivity damage mechanism shows that all kinds of sensitivities have superposition effects.

Key words: Fukang Sag, Toutunhe Formation, sensitivity, authigenic quartz, control factor