| Shanxi formation,Upper Paleozoic gas reservoirs in the east of Yanchang are wide distribution and development.As the main section of production for the Upper Paleozoic gas reservoirs,gas and production test results show higier gas production. To accurate assessment of the amount of natural gas resources of Shanxi formation, must be clear cognitive gas reserviors.This paper closely combines with the actual production practice of gas field,acording to logging, well logging, experimental analysis,gas and production test.etc,with gas reserviors of Shanxi formation as the research object, "four characteristic relations" research as the key,based on the comprehensive geological research,we make a deep research and analysis for mechanism of formation of gas reservoirs,discuss its identification methods and standards.Analysis results show that delta front subfacies sediment was mainly developed in the studied area and gas reservoirs are mainly developed in sandstones located in underwater distributary channel and mouth bar. Due to strong and multi-phase diagenesis, gas reservoir performance complex formation mechanism and kinds of forms. Both conventional high resistivity gas reservoir, and "low resistivity" gas reservoir.Determine the region "low resistivity" upper limit is 40?·m. Conventional high resistivity gas reservoirs is mainly affected by source rocks, reservoir and cap rock,but the lithology fine, complex pore structure, high-salinity water and high bound water content create the formation of "low resistivity" gas reservoir. Using logging curve overlapping, crossplot, array induction logging,etc, for qualitative identification on them, establish the log interpretation model for quantitative identification,and established a comprehensive set of criteria to identify and evaluate gas reservoir. Combined with the gas and production test to test effect,can improve the recognition accuracy of gas reservoir in the area. |
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