Abstract：Using an authentic sandstone micro-model, the flowing of oil and water was experimentally simulated in reservoirs. The micro-anisotropy was found to be an important factor in the distribution of remaining oil and the exploitation of the oilfield. The micro-anisotropy and its effect on the distribution of the remaining oil in Yanchang formation in the studied area are experimentally studied in this paper. The results show that the micro-anisotropy of Yanchang formation reservoirs is outstanding. A better quality of reservoirs is found to be related to more outstanding micro-anisotropy. Diagenesis and pore structure are the most important factors for micro-anisotropy, which, in turn, is responsible for oil displacement and forming of remaining oil, directly due to fingering flow. There are four main types of pores. They are remaining primary pore, dissolution pore, micro-crack and the micro-pore among crystals. The flow characteristics of the four pore types are quite different. The studies on the four main types of pore structures for Yanchang formation reservoirs suggest that it is better to conduct waterflooding development based on the remaining primary pore type and the dissolution pore type; or based on the micro-crack type; or based on the type of micro-pore among crystals.
2009, Vol. 27 
