(1. Research Institute of Petroleum Exploration and Development，PetroChina，Beijing 100083，China；2. Key Laboratory of Ministry of Education for Petroleum Engineering，China University of Petroleum，Beijing 102249，China；3. Key Laboratory of Gas Reservoir Formation and Development of China National Petroleum Corporation，Langfang，Hebei 065007，China；4. Institute of
Exploration and Exploitation of Dagang Oil Field，Tianjin 300280，China)
Abstract：According to the investigation argument between Chinese researchers and oversea scholars on threshold pressure gradient characteristics in ultra-low permeability reservoirs，with full diameter from Triassic outcrop by means of fully-automatic flooding system of AFS300TM provided by Core Lab in USA，an unsteady approach to test the threshold pressure gradient of saturated and unsaturated flow in the ultra-low permeability cores is proposed. The threshold pressure gradient in the saturated and unsaturated flows are analyzed with the investigation on the pressure variation from downstream and upstream of the rock cores. The experimental results indicate that the threshold pressure gradient doesn′t exist in the ultra-low permeability rocks with saturated flow of normal brine and kerosene. And the capillary force caused in the interfaces of the fluids in the unsaturated flow is the basic reason of obvious threshold pressure gradient. Moreover，the dynamic effect of capillary pressure is observed in the unsteady state flow experiments from ultra-low permeability rocks.
任晓娟，张国辉，缪飞飞. 低渗多孔介质非达西渗流启动压力梯度存在判识[J]. 辽宁工程技术大学学报：自然科学版，2009，28(增1)：273-276.(REN Xiaojuan，ZHANG Guohui，MIAO Feifei. Criterion of starting pressure gradient existence of non-Darcy flowing in low permeability porous media[J]. Journal of Liaoning Technical University：Natural Science，2009，28(Supp.1)：273-276.(in Chinese))
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2011, Vol. 30 
