A method and system for determining free gas content in shale gas reservoirs
A technology for free gas and shale gas, which is used in earth-moving drilling, wellbore/well components, etc. It can solve the problem that the evaluation results of free gas saturation are too large, lack of adsorbed gas, and the theoretical basis is not suitable for shale reservoirs, etc. problems, to achieve the effect of improving the accuracy of logging evaluation, strong operability and reliability, and significant practical value
Active Publication Date: 2020-05-22
CHINA PETROLEUM & CHEM CORP +1
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Problems solved by technology
[0004] Among the evaluation methods for free gas saturation of shale gas reservoirs mentioned above, the traditional oil and gas saturation model is established for sandstone reservoirs with intergranular pores, which is not suitable for mud shale reservoirs theoretically.
However, the method of determining the free gas saturation based on the shale pore components still lacks the evaluation of the extent to which the adsorbed gas (phase) occupies the effective pores, and the evaluation result of the free gas saturation may be larger than the real value.
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[0065] The implementation of the present invention will be described in detail below in conjunction with the accompanying drawings and examples, so as to fully understand and implement the process of how to apply technical means to solve technical problems and achieve technical effects in the present invention. It should be noted that, as long as there is no conflict, each embodiment and each feature in each embodiment of the present invention can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.
[0066] Aiming at the defects in the traditional shale free gas content calculation method, the present invention proposes a new method to determine the shale free gas content by using logging data on the basis of considering the shale adsorption phase occupying the void space, so as to improve the shale gas content. Evaluation accuracy of free gas content logging.
[0067] Such as figure 1 Shown is a method f...
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The invention discloses a method and system for determining the content of free gas of a shale gas reservoir. The method comprises the steps that logging information is utilized to determine the volume content of unit-mass shale adsorption gas under the standard state; according to the volume content of the unit-mass shale adsorption gas under the standard state, the porosity occupied by the unit-volume shale adsorption gas is calculated; according to the porosity occupied by the unit-volume shale adsorption gas, the shale reservoir total porosity and the invalid porosity, the saturability of the shale free gas is determined; and the saturability of the shale free gas is utilized to calculate the content of the shale free gas. The method and system for determining the content of the free gas of the shale gas reservoir has high operability and reliability, effectively improves shale free gas content well logging evaluating precision and has important practical value in shale gas exploration and development.
Description
technical field [0001] The invention belongs to the technical field of oil and gas exploration and development, and in particular relates to a method and system for determining the content of free gas in shale gas reservoirs. Background technique [0002] Natural gas in shale gas reservoirs mainly occurs in two states: free and adsorbed. The gas content and dominant occurrence state of shale are the key factors that determine the economics of exploration and development of shale gas reservoirs, the predicted results of production capacity and the actual changes. [0003] At present, the evaluation of shale adsorbed gas content mainly relies on isothermal adsorption equation. The determination of free gas content is to use the traditional pure sandstone oil-gas saturation model (Archie formula) or argillaceous sandstone oil-gas saturation model (Simandoux formula, Waxman-Smits two-water model, etc.), first determine the free gas saturation, and then determine free air conten...
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IPC IPC(8): E21B49/00
CPCE21B49/087
Inventor 路菁李军武清钊金武军胡瑶于文芹张爱芹
Owner CHINA PETROLEUM & CHEM CORP