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Experimental Study of Micro-structure and NMR Features of Volcanic Gas Reservoir

Author: SunJunChang
Tutor: LiuWei；GuoHeKun
School: seepage Institute of Fluid Mechanics
Course: Fluid Mechanics
Keywords: Volcanic gas reservoir Controlled mercury CT experiments NMR Lithology Microstructure T2 cutoff
CLC: P618.13
Type: Master's thesis
Year: 2010
Downloads: 357
Quote: 3
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Abstract

Recent years, worked in China's Songliao Basin, Bohai Bay, Huanghua, Junggar, and other places have been found to have some reserves volcanic rock reservoir, where volcanic gas reservoir geological reserves of more than 3 × 1012 m3. However, due to the prejudices of the history of human knowledge, and the complexity of the volcanic reservoirs, at home and abroad has not yet formed mature volcanic reservoir development program. NMR effective understanding, interpretation and evaluation of reservoir logging technology of the NMR techniques, but less in the volcanic reservoirs in terms of research, evaluation of volcanic reservoirs in the domestic application of NMR techniques work only in its infancy. System of volcanic gas reservoir microscopic pore structure and NMR characteristics for the rational development and application of NMR logging technology such special gas reservoir reservoir interpretation, evaluation can provide an important guiding role. Rate mercury testing techniques applied first, studies have shown that a large number of different lithological cores from the volcanic gas reservoir development characteristics of the micro-pore throat, very fine volcanic gas reservoir throat radius, an average of about 80% or more of the throat radius less than 0.5 μm; The seepage control reservoir throat with core permeability changes significantly, the average radius of the throat and the penetration has better correlation. Volcanic gas reservoir pore radius is relatively large, the the the main pore distribution between 150μm-200μm, pore radius changes in the permeability of a certain degree of difference. Different lithology of the reservoir pore radius of the order of granite porphyry, volcanic breccia, the rhyolite and pellets rhyolite. The quantitative proved one of the lithology of the key factors determining the reservoir microscopic pore structure characteristics. Compared with low permeability sandstone gas reservoirs, volcanic gas reservoir has a throat radius subtle characteristics of the pore radius larger than large pore throats, and the unit volume of the core the effective hole, the throat volume and porosity good correlation to its penetration rate correlation, which is contrary to the law of the sandstone reservoirs. Preferred a volcanic gas reservoirs, nuclear magnetic resonance test parameters on the basis of the three regions of volcanic gas in Daqing, Jilin and Xinjiang Tibet NMR T2 spectrum response characteristics of a comparative study, and the results show that the the different lithologies reservoir T2 spectrum has more significant differences, and no similar correspondence between sandstone in the the T2 spectrum morphology and core permeability. The error between the the volcanic rock cores NMR porosity and conventional porosity and lithology is closely related to the Jilin rhyolite tuff, Daqing rhyolite, agglomerate lava breccia lava and tuff, Xinjiang andesitic basalt NMR and conventional porosity degree in good agreement, Daqing volcanic breccia, trachyte, and Xinjiang fluorescent granite porphyry, andesite NMR conventional porosity larger error. The plasma spectral emissivity rock elements analysis mainly because of the above four lithology reservoir containing manganese, iron, nickel, paramagnetic and ferromagnetic substances due. Paramagnetic and ferromagnetic material damage establish a uniform magnetic field of the NMR instrument, so that the pore fluid relaxation rate accelerated, eventually leading to partial fluid signal can not be detected. Finally, using the mathematical fitting method gives the the four lithological NMR porosity error correction formula, to obtain a more accurate reservoir porosity provides a convenient method for NMR logging carried out in the respective areas. By centrifugal force gas water centrifugal experiments to determine calibration volcanic gas reservoirs suitable movable fluid T2 cutoff centrifugal force should be 2.76MPa, routine laboratory gas water centrifugal experiment to strike the appropriate centrifugal force of volcanic gas reservoir irreducible water saturation. Combination of capillary force equation to determine the the effective seepage of volcanic gas reservoirs throat radius lower limit of about 0.05μm, provides a solid theoretical foundation for further reservoir properties of the lower limit. NMR experiment results show that a total of 102 volcanic rock core T2 cutoff value of the average of the three regions in Daqing, Jilin and Xinjiang 49.31ms, T2 cutoff value of three regions in decreasing order of Daqing, Jilin and Xinjiang, is the cut-off values ??were 65.50ms, 41.57ms and 18.40ms. Point of view from the lithology, Daqing rhyolite T2 cutoff, the average of 91.35ms, while Xinjiang andesite minimum, average 12.71ms. The microstructure of the reservoir rock and elements affecting the the T2 cutoff size of two key factors. The NMR, centrifugation results show that, the volcanic gas reservoir movable fluid saturation increases with increasing permeability, both good correlation to its porosity correlation. The correlation coefficient Compared volcanic gas reservoir lithology is also one of the key factors that affect the size of the movable fluid saturation. In the penetration conditions close, Daqing volcanic rocks movable fluid saturation, Xinjiang volcanic rocks movable fluid saturation minimum. NMR experimental results with full-diameter core gas drive in the experimental results, the comparison of the data of the actual mine production 2.76MPa centrifugal force and centrifugal experimental calibration is the cut-off value to strike a movable fluid saturation with gas drive results, mine production data is consistent better, to show that the the centrifugation results and the NMR methods to strike a reservoir correctness movable fluid saturation.

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