Abstract:

When the oil fields exploration enters the period of high water-cut, fine description of reservoir structure is of great significance to improve the effect of oil exploration. As abandoned channels are important basis for identification of point-bar sand bodies and single channels boundary, the mud or sand and shale inter bedded sedimentary on the top of abandoned channels keeps off fluids in reservoir, so it is essential scientific basis for analyzing reservoir structure deeply and tapping remaining oil to identify the abandoned channels correctly. We take PⅠ31 layer in Xingnan development area for example, by analyzing the plane and section sedimentary characters of abandoned channels, utilizing method of relative depth contour of sand top, combining plane patterns of sand distribution and log curves response characteristics of abandoned channels, 26 abandoned channels of different size are identified in PⅠ31 layer of the area, and the width is generally around 100 m. Compared with gradually disposable abandoned channels, three sudden disposable abandoned channels sand bending degree is even bigger and extension range is shorter, and the sedimentary thickness is between 2 and 8 meters. As the lateral block action of inter bedded sandstone and mudstone or mud stone, the semi-communicated sand body combined with abandoned channels and general channels brings about unbalanced injection and production system for having injection no production or having production no injection. Top of channels sand becomes favorable zone for collection of residual oil, which is the focal points for further excavation.

Key words: reservoir structure, single channel, point bar, abandoned channel, sedimentation, Daqing