CN105912866A - Method for calculating coal bed gas adsorbing capacity - Google Patents

Abstract

The invention discloses a method for coal bed gas adsorbing capacity. First, related resource of mine area coal bed gas is collected. Then, the data is put in an absorption equation and a regression constant of the absorption equation is determined. Third, the coal bed gas absorbing capacity of the mine area is predicated. According to the invention, influence on coal bed absorption caused by pressure and temperature is taken into account comprehensively, so that mean relative deviation of a calculation value and a real measured value is reduced substantially. Therefore, the method has theoretical meaning and also practical meaning in study on coal bed gas absorption.

Description

A kind of method calculating coal bed gas adsorbance

Technical field:

The present invention relates to cbm exploration and development field, calculate coal bed gas absorption particularly to one The method of amount.

Background technology:

Coal bed gas is to adsorb at matrix of coal particle surface, be free in coal hole or be dissolved in It coal seam water is auxiliary hydrocarbon gas.The quantitative calculation method of coal bed gas adsorbance is coalbed methane reservoir The key evaluated and main difficult technical, utilizing well-log information to calculate its content becomes important channel, Its computational accuracy directly influences the exploration and development decision-making of coal bed gas.

Matrix of coal solid particle to the adsorbance of gas simultaneously by pressure and temperature effect, and along with burying The pressure of deep change coal seam reservoirs changes with temperature simultaneously；At present, coal bed gas adsorbance is calculated Only consider pressure change impact, conventional method have Langmuir isothermal adsorpting equation, Freundlich Tellurium determination, extension Langmuir isothermal adsorpting equation, and digital simulation Error.Above-mentioned equation does not considers the alternating temperature impact on adsorbance, so isothermal adsorption theory is not up to The actual requirement of cbm exploration exploitation.

Summary of the invention:

The technical problem to be solved in the present invention is the method calculating coal bed gas adsorbance, and the method is comprehensive Consider temperature, the pressure impact on coal bed gas adsorbance, prediction coal seam aspiration is greatly improved attached The degree of accuracy of amount, the exploration and development to coal bed gas has practice guiding action.

The invention provides a kind of method calculating coal bed gas adsorbance, realized by following steps:

Step one: the adsorbance of detection coal seam, mining area coal bed gas at different temperatures and pressures.Including Under constant temperature, the adsorbance that different pressures is corresponding；Under constant-pressure conditions, the suction that different temperatures is corresponding Attached amount.

Step 2: data step one detected are brought in adsoption equation:

In formula:

V: coal bed gas adsorbance；

The micropore geometrical body constant of A: fixing porous media；

B: absorption flow coefficient, absorption site zone is correlated with；

Δ: adsorb the energy difference between a binding molecule lowest potential energy and activation energy in mass flow；

β: adsorption isotherm equation constant；

M: methane molecule amount；

T: observed temperature (K)；

P: observed pressure.

Detection data are returned with formula 1 MATLAB software, calculates the recurrence of adsoption equation Constant A, B, β and Δ, bring the recurrence constant of calculating formula one into and carry out next step calculating.

Step 3: bring different coal temperature, force value in this mining area Conventional Logs into formula one, Calculate the adsorbance of different depth coal seam coal bed gas.This temperature, pressure and absorption value are used 3-D view made by Matlab software, this figure can intuitively reaction temperature and pressure to coal seam aspiration The impact of attached amount, coal bed gas adsorbance under the most measurable different temperatures, pressure.

Further, by the coal bed gas adsorbance under different temperatures, pressure in formula 1 calculation procedure one, It is designated as V_Calculate, calculate actual measurement adsorbance V according to following formula_{Actual measurement}With V_CalculateMean relative deviation:

In formula:

V_{Actual measurement, i}: the actual measurement adsorbance under certain group temperature, pressure；

V_{Calculate, i}: the calculating adsorbance under certain group temperature, pressure；

The accurate of equation prediction mining area coal bed gas adsorbance is determined according to mean relative deviation value Property.

A kind of method calculating coal bed gas adsorbance of the present invention has the beneficial effects that: the present invention studies The coal bed gas adsoption equation gone out, considers pressure, impact that coal bed gas is adsorbed by temperature, significantly Degree reduces the mean relative deviation of value of calculation and measured value；Therefore the method is to research coal seam aspiration Attached existing theory significance, is more of practical significance.

Accompanying drawing explanation

Fig. 1 is adsorbance and temperature, pressure graph of a relation.

Detailed description of the invention:

In order to make the object, technical solutions and advantages of the present invention clearer, below in conjunction with concrete real Execute example to be described in further detail.

Step one: collect Xiangshan, Hancheng, Shaanxi Province Xin Jing 1# pressure tap coal sample, at a temperature of detecting many groups The adsorbance that under the adsorbance that different pressures is corresponding, and many group pressure, different temperatures is corresponding.Data arrange In following table.

Step 2: in data bring adsoption equation in table:

$V=\frac{1}{\sqrt{MT}}\[A+{\mathrm{BP}}^{\mathrm{\β}}{T}^{1.5}\exp \left(\frac{\mathrm{\Δ}}{T}\right)\]$

In formula:

V: coal bed gas adsorbance；

The micropore geometrical body constant of A: fixing porous media；

B: absorption flow coefficient, absorption site zone is correlated with；

Δ: adsorb the energy difference between a binding molecule lowest potential energy and activation energy in mass flow；

β: the constant of adsorption isotherm equation；

M: methane molecule amount；

T: observed temperature (K)；

P: observed pressure.

Data and the formula 1 MATLAB software step one collected return, and calculate suction respectively Recurrence constant A, B, β that attached amount is corresponding and Δ；Result is listed in the table below:

Step 3: bring the temperature of different coal, force value in this mining area Conventional Logs into formula One, calculate the adsorbance of coal bed gas in different depth coal seam.

By temperature be 280-330 (K), pressure be 0-10MPa and absorption value Matlab software Doing 3-D view (see photo), coal bed gas can reaction temperature and pressure be adsorbed by this figure intuitively The impact of amount, coal bed gas adsorbance under the most measurable different temperatures, pressure.

Further, by the coal bed gas adsorbance under different temperatures, pressure in formula 1 calculation procedure one, It is designated as V_Calculate, calculate V according to following formula_{Actual measurement}With V_CalculateMean relative deviation:

In formula:

V_{Actual measurement, i}: the actual measurement adsorbance under certain group temperature, pressure；

V_{Calculate, i}: the calculating adsorbance under certain group temperature, pressure；

Calculating mean relative deviation δ is 7.25.Ratio is calculated with existing isothermal adsorpting equation Mean relative deviation 13 reduces 5.75, and the degree of accuracy of calculating is greatly improved.

Claims (2)

1. the method calculating coal bed gas adsorbance, it is characterised in that: the method comprises the following steps:

Step one: the adsorbance of detection coal seam, mining area coal bed gas at different temperatures and pressures；Including Under constant temperature, the adsorbance that different pressures is corresponding, under constant-pressure conditions, the suction that different temperatures is corresponding Attached amount；

Step 2: data step one detected are brought in adsoption equation:

In formula:

V: coal bed gas adsorbance；

The micropore geometrical body constant of A: fixing porous media；

B: absorption flow coefficient, absorption site zone is correlated with；

Δ: adsorb the energy difference between a binding molecule lowest potential energy and activation energy in mass flow；

β: adsorption isotherm equation constant；

M: methane molecule amount；

T: observed temperature (K)；

P: observed pressure；

Detection data are returned with formula 1 MATLAB software, calculates the recurrence of adsoption equation Constant A, B, β and Δ, bring the recurrence constant of calculating formula one into and carry out next step calculating；

Step 3: bring different coal temperature, force value in this mining area Conventional Logs into formula one, Calculate the adsorbance of different depth coal seam coal bed gas；This temperature, pressure and absorption value are used 3-D view made by Matlab software, this figure can intuitively reaction temperature and pressure to coal seam aspiration The impact of attached amount, coal bed gas adsorbance under the most measurable different temperatures, pressure.

A kind of method calculating coal bed gas adsorbance, it is characterised in that: institute State in step 3, by the coal bed gas adsorbance under different temperatures, pressure in formula 1 calculation procedure one, It is designated as V_Calculate, calculate actual measurement adsorbance V according to following formula_{Actual measurement}With V_CalculateMean relative deviation:

In formula:

V_{Actual measurement, i}: the actual measurement adsorbance under certain group temperature, pressure；

V_{Calculate, i}: the calculating adsorbance under certain group temperature, pressure；

The accurate of equation prediction mining area coal bed gas adsorbance is determined according to mean relative deviation value Property.