Tri-media reservoir characteristic of fractured tight gas reservoir of gasfield A, Kuqa Depression, Tarim Basin.

The reservoir of gasfield A, which located in Kuqa Depression of Tarim Basin, has features of large burial depth, and belongs to fractured tight gas reservoir. As the pore-throat is small and the pore structure is complex, it's difficult to do the pore throat structure characterization by conventional methods. In this paper, lots of advanced technologies, such as LSCM, FESEM, Micro-CT, Nitrogen adsorption and NMR, are used to do the pore throat structure characterization. It's found for the first time that, the reservoir of gasfield A has microscopic characteristic of tri-media, which contain large pore-throat medium, small pore-throat medium and fractures. The volume of large pore-throat medium approximately equals to the volume of small pore-throat medium, but large pore-throat medium's contribution to the matrix permeability accounted for 95%. The pore and throat collocations are mainly big pore-coarse throat, small pore-fine throat,and small pore-coarse throat are secondary. Absolute fracture porosity is only about 0.01%-0.5%, 1.8%-2.8% of total reservoir porosity,but fracture is main seepage channel of reservoir, the permeability of fractured samples is about 10 times or 100 times of samples without fracture. Based on the research of reservoir characteristics above, the conceptual model of tri-media reservoir is established, which can interpret the reservoir seepage characteristics well. The research idea in this paper will be helpful to other similar reservoir. [ABSTRACT FROM AUTHOR]