Experimental Study On Pore And Seepage Characteristics Of Low Permeability Tight Sandstone Gas Reservoirs In D Area

This paper concentrated on analyzing micro pore structure and seepage characteristics of a low permeability tight sandstone gas reservoir systemically for a certain block in Ordos basin according to a large number of rock core laboratory tests. The analytical methods from qualitative analysis to quantitative characterizatian,and the combination of dynamic and static,micro and macro have been highlighted. Focused on exploring the influence of pore types, pore-throat structure with parameters, mineral content, gas-water relative permeability-characteristics, reservoir sensitivity, etc to this area of the reservoir. The reserves available conditions of low permeability and tight water bearing reservoir have been analyzed simultaneously through the casting thin sections microscopic imaging analysis, micro CT scanning experiment, gas-water relative permeability experiments, stress coupled seepage experiment research, water sensitivity evaluation experiments, gas reservoir of depletion exploitation physical simulation experimental research, etc.Specific items fall into 6 categories, (1) Recognized it belongs to a typical low permeability tight reservoir for the average porosity of rock sample was 8.29% and its average permeability was 0.216mD through physical properties of conventional test. (2) The casting thin sections experiments analyzed the lithology, type of cementation, facial porosity and porosity types. (3) Attained these parameters much more than pore throat radius, throat-to-pore radius ratio and pore throat volume micro CT scanning experiments. (4) Gas-water relative permeability experiments tested the rock sample of irreducible water saturation, water saturation and permeability of isotonic point, the regional seepage characteristics. Evaluated the seepage of the reservoir capacity and made a deep analysis of the percolation mechanism of the air water two phase flow. (5) Obtained a result that D block with stronger reservoir stress sensitivity and a wholly weak water sensitivity based on series of reservoir sensitivity evaluation experiments that rock sample have been tested seepage routine under the changing net stress, rock permeable sensitivity of different simulated formation water salinity. (6) Gas reservoir of depletion exploitation physical simulation experiments found the main influence factors of low permeability tight gas reservoir recovery efficiency were reservoir physical property and water saturation as researched the multi-factor to the influence regular pattern of recovery efficiency.Recognized the low permeability tight sandstone gas reservoir characteristics from four perspectives experiments, as microscopic pore structure characteristics, gas-water relative permeability curve variation characteristics, reservoir sensitivity characteristics and the influence factors of recovery efficiency in detail. The research conclusion can be used as the basis information of gas reservoir engineering research for the low permeability tight sandstone gas reservoir for this gas reservoir engineering based on comprehensive evaluation and analysis through plenty of experiments data.