A Calculation Method of Gas Loss

Abstract

The invention relates to a method for estimating gas loss through the relationship between accumulated desorption amount and time. A large number of experiments have shown that the relationship between the cumulative desorption amount and time in the initial stage after the pressure relief of coal cuttings is V =A(t / T)n, but the power exponent n is not a constant, n is related to the gas pressure and changes with time, accurately determining the power exponent n of the cumulative desorption amount is the key to calculating the gas loss. In order to accurately calculate the amount of gas loss, ① First, evaluate the gas pressure of the coal seam through on-site measurement; ② Measure the gas content on-site and record the cumulative desorption amount over time t at the same time as the observation time t V t, total desorption time T, loss time t0; ③Determine the value of n under the pressure condition of the coal seam to be tested in the laboratory; use the least square method to obtain ln V The unary regression relational expression between t and ln[(t+t0)n-t0n], where the intercept is ln(A / Tn), put in the n value and T value to get the A value; ④ use the A value, T value, n value into V 0=A(t0 / T)n to get the amount of gas loss V 0.

Description

technical field [0001] The invention belongs to the technical field of coal seam gas content measurement, and in particular relates to a gas loss calculation method. Background technique [0002] Coal seam gas content is one of the main parameters of coal seam gas, and it is an important basic parameter for mine ventilation design, gas emission prediction, gas outburst prediction, and gas drainage design. [0003] The gas content is composed of three parts: loss, desorption, and residual volume, among which the desorption volume and residual volume can be measured more accurately, while the gas loss volume is mainly calculated through the desorption law, and the calculation methods mainly include: method and exponent method. [0004] Method: It is based on the exposure of the coal sample for a period of time t internal cumulative desorption V and It is determined in a linear relationship, that is: [0005] [0006] In the formula: a, b are undetermined constants,...

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Problems solved by technology

[0027] Similarly, the power exponent method uses the desorption strength of the cuttings after a period of desorption to calculate the initial desorption strength of the cuttings just exposed, and the obtained power exponent k not accurate

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