Comprehensive evaluation method for hydration capability of heterogeneous shale reservoir

Abstract

The invention discloses a comprehensive evaluation method for a hydration capability of a heterogeneous shale reservoir. The method comprises the following steps: preparing a rock sample according torock of a shale reservoir section, and drying the rock sample to constant weight; measuring porosity and permeability of the rock sample, and obtaining a physical property index of the rock sample according to the porosity and permeability; measuring mineral components of the rock sample, and acquiring a brittleness index of the rock sample according to the mineral components; carrying out a rocksample imbibition experiment test to obtain a hydrophilicity index of the rock sample; and determining a rock sample hydration effect comprehensive index according to the physical property index, thebrittleness index and the hydrophilicity index of the rock sample, and carrying out comprehensive evaluation on a shale rock sample hydration effect capability by adopting the rock sample hydration effect comprehensive index. The method can quantitatively characterize the hydration capability of the shale, the test and application method is simple to operate, a calculation result is more accurate,a large number of mine field experiments are not needed, the economic cost is greatly reduced, and an important scientific basis is provided for optimization of the soaking time of a shale gas well.

Description

technical field [0001] The invention relates to the field of petroleum and natural gas engineering, in particular to a comprehensive evaluation method for the hydration capacity of heterogeneous shale reservoirs. Background technique [0002] Horizontal well segmented multi-cluster volume fracturing is a key technology for efficient development of shale gas. Different from conventional sandstone, due to differences in geological characteristics and fracturing techniques, shale gas wells show special flowback characteristics after volume fracturing : Negative correlation between gas production and flowback rate, decrease in water production after simmering, increase in gas production, large difference in flowback rate, etc. (Dong Dazhong, Wang Yuman, Li Xinjing, et al. Thoughts on new breakthroughs and development prospects of China's shale gas exploration and development[J ]. Natural Gas Industry, 2016, 36(1): 19-32). [0003] At present, due to the special flowback charact...

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Problems solved by technology

[0008] The above methods are single-factor qualitative analysis of rock mechanical properties and microstructure changes during shale hydration, and lack quantitative characterization of shale hydration capacity

At the same time, the water-phase imbibition and hydration of shale reservoirs are a dynamic equilibrium process. Shale hydration induces micro-cracks, which further promotes the shale's hydrophilic ability. Conversely, the increase of shale's hydrophilic ability further promotes shale hydration. Therefore, how to quantitatively test the hydrophilic ability of shale plays an important role in evaluating the hydration of shale reservoirs, and previous studies did not consider the influence of reservoir confining pressure and temperature on shale hydration, while shale is usually In high-temperature and high-pressure reservoirs, it is difficult to answer the question whether shale water phase imbibition can induce micro-fractures under the confining pressure and temperature conditions of the reservoir. Therefore, it is necessary to comprehensively consider different factors to quantitatively characterize the hydration capacity of shale, and then Provide scientific basis for optimization of shale gas well flowback system

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