| With the deepening of the domestic and international oil and gas layer exploration and development, low porosity and low permeability sandstone reservoir increasing China’s natural gas reserves and production will continue to be a bright spot. Due to the occurrence of complex geological conditions, strong heterogeneity and effective sand body connectivity characteristics of poor, the gas logging response characteristics become complex and it’s very difficulty to the logging identification and evaluation. We should study of low permeability reservoir in-depth, which has very important practical significance for the exploration and development of oil and gas field, for the development effect of low permeability reservoir is poor.Structural position of Hangjinqi area located Yimeng uplift of northern Ordos Basin. The structure is not development, mainly in the stratum, lithology trap, mainly alluvial fan near source characteristics of fluvial facies, diagenesis influence, caused the reservoir pore structure, strong heterogeneity. Hangjinqi area of Upper Paleozoic reservoirs belongs to the typical low porosity and low permeability reservoir, and its reservoir lateral changes. What’s more, its serious heterogeneity and the reservoir identification difficult. The amplitude of structure, lithology and physical limitations, gas water differentiation degree difference, gas and water logging response characteristics were not significantly different, resulting in difficulties in reservoir fluid identification. With the exploration process of Hangjinqi area, to speed up the exploration and development of space expands, logging evaluation technique need to be further deepened, need to determine the interpretation standards for each segment of gas layer, two times of well data processing.The thesis makes full use of all kinds of logging data collected, the comprehensive geological data, logging data and core data, which focuses on the analysis of the upper Paleozoic Permian Lower Shihezi Formation, Shanxi formation of Carboniferous Taiyuan formation, the lithology, physical properties and gas logging response characteristics, and analysis of flow influence factors. Based on statistics of geological and the logging data, we can analyze the clastic rock reservoirs with low porosity and low permeability. We can summary the pore distribution characteristics from the macro or micro, and understand the macroscopic characteristics of pore structure log response rule. According to the reservoir features, combined with geology, logging, capillary pressure data, testing and other information, we can use comprehensive utilization of sonic, density, neutron logging data to establishe the Hangjinqi area of Upper Paleozoic reservoir porosity calculation of geophysical model and response equation. According to geological conditions, we can analyse rock electricity experiment data, set partitioning in hierarchical determination of rock electrical parameters and analysis on the choice of saturation calculation model, We use the Archie model to calculate the water saturation. Related to the physical analysis data and gas test data as the basis, we can divided into Lower Shihezi Formation reservoir petrophysical property cutoffs standard.In reservoir identification basis, we can make full use of the existing test results and analyse the characteristics and influencing factors of log responses of reservoirs, gas and water layer, layer. It reflecte the different reservoir gas, water, dry the differences between the layers from different angles using a variety of methods.We analyse various discriminant method of fluid properties and its application in the research the selected area, judging from method for reservoir fluid properties. The paper uses the porosity curve overlapping method (dual porosity overlapping method and the methods of three-porosity overlay), resistivity and acoustic intersection method, resistivity and porosity crossplot method to identificate the reservoir fluid properties. We can use of oil-bearing description data and oil testing, production test data, partition based on standard and interpretation chart logging identification of oil gas reservoir, gas shows effects are more obvious, to improve the accuracy of gas water identification.Because of the natural gas’s low hydrogen index and low density,it exhibit unique properties in logging curve. Based on the volume model, the paper make full use of neutron-acoustic combined estimated gas indication (SG). Driving acoustic experimental data by studying small rocks, we can investigate the acoustic effects of pressure and temperature and analyse the relationship between acoustic velocity and gas saturation. Then we can set up the gas saturation and wave velocity and saturated water wave velocity ratio (Vp/Vpw), finally calculated gas saturation indication parameters, and provides the gas saturation indicator (SGI), improve the saturation calculation precision.Hangjinqi area sandstone has the characteristics of low porosity, low permeability, not strong heterogeneity. Its pore structure is complex. The noise ratio is low, and the gas and water logging response characteristics were not significantly different. Reservoir identification and reservoir evaluation is difficult using conventional logging. Based on nuclear magnetic resonance logging, cross dipole acoustic logging and imaging logging method for identification of gas layer extraction, the paper improve the identification accuracy and provides a new basis for the identification of gas layer.Based on comprehensive evaluation method of reservoir through the Hangjinqi area of Upper Paleozoic, the paper can effectively improve the accuracy of reservoir parameters interpretation accuracy and oil-water layer recognition. It is more comprehensive, more in-depth understanding of Hangjinqi area geological condition of forming gas pools and expand the field of natural gas exploration. Of course,it provides effective technical support on looking for a relatively good reservoir. |
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