Study On Log Evaluation Method Of Tight Sandstone Reservoirs In ES3of Qingshui Sub-sag

With exploration and development of Liaohe depression, tight reservoirs have becomeone of the most important beds of interest in Liaohe depression. In this paper, the key objectsare the tight sandstone reservoirs in ES3of Qingshui sub-sag with ultra-low permeability,shaliness and complex pore structure.First, based on log-standardization, four-property relationship of tight reservoirs in thisarea is researched by using coring data, core analysis, well testing data and log data. Based onpetrophysical experiment, coring data, well testing data, log data, the characters of lithology,physical property, mineral features, formation water salinity and pore structure in this area arereseached by using statistical methods, and the results show that the tight sandstone reservoirsin ES3of Qingshui sub-sag have characters of low porosity, ultra-low permeability,shale-bearing, more microscopic capillary pores, high irreducible water saturation andcomplex pore structure. Second, using experimental data of tight sandstone reservoirs in ES3of Qingshui sub-sag, parameter interpretation models, such as shale content, porosity,permeability and irreducible water saturation are established. Thirdly, based on conductiverules and pore stuctures, considering shaliness and pore structure on sand conductivity, theconductivity model of tight sandstone reservoirs in ES3of Qingshui sub-sag is establishedwith the effective medium conduction theory and the equivalent rock element theory. Theequivalent rock element theory is used to describe the influence of pore-throat ratio on sandconductivity, and the effective medium conduction theory is used to describe the influence ofshale on sand conductivity. Parameters of percolation exponent, percolation rate and porestructure efficiency are determine with the experimental data. Through analyzing theinfluence of percolation exponent, percolation rate and pore structure efficiency on rockconductive rule, it found that formation resisitivity decreases as pore structure efficiencyincreases. The log data in ES3Formation in Qingshui sub-sag are processed and interpretedwith the proposed model, and the results show that the model can be well applied in loginterpretation of tight sandstone reservoirs in ES3of Qingshui sub-sag.