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Infopetro -> Technology Brealcthrough |
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A Logging Evaluation Method For Gas Content Of Shale Gas Reservoirs In Sichuan Basin
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2017-07-14 |
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Gas content, as an important indicator for shale gas reservoir evaluation, directly determines whether a shale gas block is of industrial production value. Gas content is mainly composed of free gas and adsorbed gas, and is impacted by many factors, including porosity, gas saturation, formation pressure, formation temperature and total organic carbon content. A set of systematic logging evaluation methods for the gas content of shale gas reservoirs was developed based on a comprehensive study of the shale gas reservoirs of Lower Silurian Longmaxi Fm in the southern Sichuan Basin. First, a calculation model for the key parameters of Langmuir equation was built up by conducting isothermal adsorption experiments on shale cores. And the calculation accuracy of adsorbed gas content was improved by analyzing and correcting its main influential factors, such as reservoir temperature, reservoir pressure and TOC. Second, porosity and water saturation of shale reservoirs are precisely evaluated to provide a basis for accurate calculation of free gas content. Third, the adsorbed methane occupies a certain pore space, so the calculated gas content is more accurate after the effect of adsorbed gas volume is excluded, and it is consistent with the core analysis data. To sum up, the calculation method for gas content of shale gas reservoirs in Sichuan Basin is developed experimentally and theoretically, and if of good adaptability in this block. So it provides an effective technical support for production testing horizon selection and block resource potential evaluation. |
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