Abstract:

The same flow-units have the same properties of rocks and the flow-capacity, and consistent seepage and flood-out characteristics are similar in the development of the well. Using the view of analytic hierarchy, the flow-units of ultro-low permeability sandstone reservoir are divided basing on the work of single-sand-body contrasting, sedimentary micro-faces, inter-layer and seepage-barriers searching, and combining with the reservoir characteristics of low permeability sandstone. Using the method of multi-parameter statistical cluster analysis, the flow-units of Chang4+5²₂ single sand bed of Yanchang Formation are divided to A category, B category and C category. The experiment of micro-water-flooding describes the different of pore structure ，micro-water-flooding seepage features and oil displacement efficiency diversity. And the rationality of classification results is verified by the experiment from the viewpoint of dynamic analysis. It suggests that: A-type and B-type flow-units have the characteristics of thicker of sandstone and higher FZI, good-connectivity, lower displacement pressure, and the flow-unit of A and B are beneficial to higher-yield area in Jiyuan oilfield. The flow-unit of C has bad water-flooding, and is the benefit area of remained-oil distribution and the potential position of increasing productivity.

Key words: ultro-low permeability, flow-unit, hierarchical analysis, micro-water-flooding experiment, Ordos basin, Yanchang Formation