CN104713803B - Method for accurately measuring absorbed phase density of methane on shale - Google Patents

Abstract

The invention relates to a method for accurately measuring absorbed phase density of methane on shale. The method comprises the following steps: 1) smashing a piece of shale sample to be 60-80 meshes, and dividing the powder into two; 2) performing a volumetric method isothermal adsorption experiment on the first shale sample, and obtaining a calculation model of the amount of the adsorbed state methane substance; 3) performing a weight method isothermal adsorption experiment on the second shale sample, and obtaining a calculation model of the mass of the adsorbed state methane; 4) performing adsorbed phase volume correction on the calculation model of the amount of the adsorbed state methane substance, obtained in the step 2) and the calculation model of the mass of the adsorbed state methane, obtained in the step 3), so as to obtain the corrected substance amount calculation model and the corrected mass calculation model of the adsorbed state methane; 5) according to a definition formula of the amount of substance, determining the mass and the volume of the adsorbed state methane; 6) according to the definition of the density, determining an exact value of the adsorbed phase density of methane on the shale.

Description

A kind of accurate measurement methane adsorbs the method for phase density on shale

Technical field

The present invention relates to a kind of method that accurate measurement methane adsorbs phase density on shale, belongs to geological exploration techniques neck Domain.

Background technology

Chinese scholars are inhaled using volumetric method isothermal mostly when the absorption property to coal measures mud stone and shale is studied Attached instrument, in recent years with shale gas exploration and development flourish, gravimetric method isothermal adsorption instrument is also just gradually by Chinese scholars Received, the latter is with magnetic suspension balance as the instrument that predominantly detects, and test result is more accurate.

Chinese scholars are found when being studied coal measures mud stone and shale isothermal adsorption characteristics using volumetric method, in profit When being tested shale adsorbed methane with volumetric method, the presence for adsorbing phase volume will reduce the body of free gass in sample cell Product, and then impact is produced on the test result of shale absorbability.And absorption phase is have ignored in correlational study before this Volume is present, and this will cause for the evaluation of absorbability has relatively large deviation.For such problem, a part of scholar's examination From different angles correction adsorbs phase volume to the impact produced by adsorbed gas aptitude tests to figure.But it is no matter right in which way Impact produced by absorption phase volume is corrected, and substance conservation principle is followed at last, therefore it is nothing to adsorb the determination of phase density The problem that method is avoided, and the accuracy of absorption phase density will directly affect correction result.

Because the research at present for adsorption isotherm experiment adopts volumetric method isothermal adsorption instrument, gravimetric method isothermal adsorption mostly The use of instrument is relatively fewer, and the unification of means of testing leads to not accurately be tested from experimental viewpoint to adsorbing phase density, Therefore, at present both at home and abroad for the research of absorption phase density is still in theory hypothesis and mathematics optimizing phase.Yee D.(1994) Think when temperature is higher than critical temperature (under normal circumstances), to adsorb the limiting density that phase density is equal to gas compression, pushed away with this It is 0.375g/cm by the absorption phase density of methane³.Arri (1992) assumes that absorption phase density is close for the liquid under atmospheric boiling point Degree, the absorption phase density with this inference methane is as 0.421g/cm³.Katsuyuki Murayta (2001) are obtained using empirical equation It is about 0.59g/cm to methane adsorption phase density³.Research above will adsorb phase density as definite value, not consider temperature, pressure Etc. the impact that condition is produced, for this purpose, German scholar Berhard M.Krooss and its team (2008,2010,2012,2013, 2014) Gibbs is combined with regard to the definition adsorbed with langmuir equation, using absorption phase density as undetermined parameter, from mathematics Absorption phase density of the optimization angle to methane and carbon dioxide on coal measures mud stone and shale is evaluated, and obtains different adsorbents With absorption phase density of the adsorbate combination under condition of different temperatures.Similar, domestic scholars Zhou Li (2000,2001) will Gibbs in combination with D-A equations, derives absolute adsorption amount model, and optimization condition of different temperatures to the definition for adsorbing Absorption phase density of the lower methane on AX-21 activated carbons, temperature methane adsorption phase density in 233K-333K is 0.15g/cm³- 0.350g/cm³.This method being optimized in combination with isotherm adsorption model and then to absorption phase density, it is to adsorbing phase The accuracy of density evaluation result will be largely dependent upon the suitability of isotherm adsorption model, and shale pore structure is multiple Miscellaneous, the suitability of isotherm adsorption model is difficult to determine, waits further to grind hence with the evaluation result obtained by the method Study carefully.

To sum up, forefathers are to adsorbing the research of phase density still in theory hypothesis or mathematical optimization stage, not yet from experiment angle Degree is accurately tested it, and different researchers result of study differs greatly, and eventually without final conclusion, this will adsorb to objective evaluation rock Gas ability produces considerable influence.

The content of the invention

For the problems referred to above, it is an object of the invention to provide it is a kind of based on laboratory facilities and strong applicability accurate measurement first Alkane adsorbs the method for phase density on shale.

For achieving the above object, the present invention is employed the following technical solutions：A kind of accurate measurement methane adsorbs phase on shale The method of density, comprises the following steps：1) one piece of mud shale sample comminution is divided into two parts to 60~80 mesh；2) to first part Mud shale sample carries out volumetric method adsorption isotherm experiment, and obtains amount n of the material of ADSORPTION STATE methane_{Absorption CH4}Computation model；3) Gravimetric method adsorption isotherm experiment is carried out to second part of mud shale sample, and obtains quality m of ADSORPTION STATE methane_{Absorption CH4}Calculating mould Type；4) to step 2) in resulting ADSORPTION STATE methane material amount n_{Absorption CH4}Computation model and step 3) in it is resulting Quality m of ADSORPTION STATE methane_{Absorption CH4}Computation model carry out adsorb phase volume amendment, obtain the revised of ADSORPTION STATE methane The computation model of the amount of material and the computation model of quality；5) according to the defined formula of the amount of material, with reference to step 4) in two Individual computation model, obtains quality m of ADSORPTION STATE methane_{Absorption CH4}With volume V_Absorption；6) according to the definition of density, methane is tried to achieve in shale Upper absorption phase density ρ_AbsorptionExact value, i.e.,：

The step 2) in, amount n of the material of ADSORPTION STATE methane is set up by volumetric method adsorption isotherm experiment_{Absorption CH4}Meter The process for calculating model is as follows：

1. arranging one includes reference cell, sample cell, the first valve, the second valve, the first thermobarometer, the second thermobarometer, helium The volumetric method isothermal adsorption instrument of gas source of the gas and methane source of the gas, wherein, reference cell connects respectively an air inlet pipeline and an outlet pipe First valve is arranged on air inlet pipeline, and the second valve is arranged on outlet pipe, the end connection sample cell of outlet pipe；The One thermobarometer is arranged in reference cell, and the second thermobarometer is arranged in sample cell；Helium source of the gas and methane source of the gas pass through pipeline It is connected to the initial end of air inlet pipeline；2. it is put into system evacuation in sample cell after first part of mud shale sample, closes the Two valves, then open the first valve, and a certain amount of helium is filled with reference cell using helium source of the gas, and the first valve is closed afterwards Door, after the temperature and pressure of reference cell is stable, records temperature T of helium in reference cell_{Reference cell He}With pressure P_{Reference cell He}Value, root According to the equation of gas state, have：

P_{Reference cell He}V_{Reference cell}=Z_{Reference cell He}n_{Reference cell He}RT_{Reference cell He}

In above formula, V_{Reference cell}For the volume of reference cell；Z_{Reference cell He}For the school of the imperfect gas shape body equation of helium in reference cell Positive divisor；n_{Reference cell He}The amount of the material of helium to be filled with reference cell；R is ideal gas constant；

3. the second valve is opened, the helium in reference cell enters sample cell by outlet pipe, treats reference cell and sample cell Temperature and pressure it is stable after, record temperature T of helium in the system that reference cell is constituted with sample cell_{System He}And pressure P_{System He}Value, now, according to the equation of gas state, have：

P_{System He}V_{System freedom}=Z_{System He}n_{System He}RT_{System He}

In above formula, V_SystemThe resulting free sky of system after volume and deduction sample volume for reference cell 1 and sample cell 2 Between volume；Z_{System He}In the system being made up of reference cell 1 and sample cell 2 correction of the imperfect gas shape body equation of helium because Son；n_{System He}For the summation of the amount of the material of the helium in reference cell 1 and sample cell 2；

4. according to mass conservation law, open the helium content before the second valve in reference cell and be equal to the second valve of opening Helium total content in later reference cell and sample cell, i.e.,：

n_{Reference cell He}=n_{System He}

By step 2. and 3. in resulting equation substitute into above formula, obtain

5. by step, 4. gained formula tries to achieve volume V of system free space_{System freedom}；

6. again to system evacuation, then by the second valve closing, the first valve is opened, using methane source of the gas to ginseng Than being filled with a certain amount of methane in pond, the first valve is closed afterwards, after the temperature and pressure of reference cell is stable, record reference cell Temperature T of middle methane_{Reference cell CH4}With pressure P_{Reference cell CH4}Value, according to the equation of gas state, have：

P_{Reference cell CH4}V_{Reference cell}=Z_{Reference cell CH4}n_{Reference cell CH4}RT_{Reference cell CH4}

In above formula, Z_{Reference cell CH4}For the correction factor of the imperfect gas shape body equation of methane in reference cell；n_{Reference cell CH4}To fill Enter the amount of the material of methane in reference cell；

7. the second valve is opened, the methane in reference cell enters sample cell by outlet pipe, treats reference cell and sample cell Temperature and pressure it is stable after, record temperature T of methane in the system that reference cell is constituted with sample cell_{System CH4}And pressure P_{System CH4}Value, now, according to the equation of gas state, have：

P_{System CH4}V_{System freedom}=Z_{System CH4}n_{The free CH4 of system}RT_{System CH4}

In above formula, Z_{System CH4}The imperfect gas shape body equation of methane in the system being made up of reference cell and sample cell Correction factor；n_{The free CH4 of system}For the amount of the material of the methane of system free space.

8. according to mass conservation law, open the methane content before the second valve in reference cell 1 and be equal to the second valve of opening The methane content of methane content and ADSORPTION STATE after door in system free space, i.e.,：

n_{Reference cell CH4}=n_{The free CH4 of system}+n_{Absorption CH4}

In above formula, n_{Absorption CH4}For the amount of the material of the methane of ADSORPTION STATE；

9. by step 6. and 7. in resulting equation substitute into step 8. in the formula of gained, obtain the thing of ADSORPTION STATE methane Amount n of matter_{Absorption CH4}Computation model：

V in formula_{System freedom}5. it is calculated by step.

The step 3) in, quality m of ADSORPTION STATE methane is set up by gravimetric method adsorption isotherm experiment_{Absorption CH4}Calculating mould The process of type is as follows：

1. one gravimetric method isothermal adsorption instrument is set, and the top of the adsorption instrument is a magnetic suspension balance, and bottom is one closed Housing, the suspended end in housing installs a sample cylinder, and a float is provided with above sample cylinder；The adsorption instrument is provided with two Gear, when the first gear is placed in, balance weighs the weight of sample cylinder, and balance registration is equal to the weight of sample cylinder and deducts gas pair The buoyancy of sample cylinder；When the second gear is placed in, balance weighs the weight of float and sample cylinder, and balance registration is equal to sample cylinder Weight deducts the buoyancy suffered by sample cylinder and float with the weight sum of float；Further, adsorption instrument is in the second gear Balance registration is subtracted each other with the balance registration in the first gear, that is, obtain between the buoyancy suffered by the weight and float of float Difference；

2. nitrogen is filled with into housing, is then measured under air pressure conditions a and b respectively, measurement meets following relation Formula：

m_{R1 floats}=m_Float-V_Floatρ₁

m_{R2 floats}=m_Float-V_Floatρ₂

m_R1=m_{Empty barrel}-V_{Empty barrel}ρ₁

m_R2=m_{Empty barrel}-V_{Empty barrel}ρ₂

In above formula, m_{R1 floats}For nitrogen pressure be a, adsorption instrument be in the second gear when balance registration be in the first gear When balance registration difference；m_{R2 floats}For nitrogen pressure be b, adsorption instrument be in the second gear when balance registration be in first grade The difference of balance registration during position；m_FloatFor quality；V_FloatFor the volume of float；ρ₁For density of the nitrogen when air pressure is a；ρ₂For Density of the nitrogen when air pressure is b；m_R1For nitrogen pressure be a, adsorption instrument be in the first gear when balance registration；m_R2For nitrogen Balance registration when gas air pressure is b, adsorption instrument is in the first gear；m_{Empty barrel}For the quality of sample cylinder；V_{Empty barrel}For the volume of sample cylinder；

Density p of the nitrogen under air pressure conditions a and b is tried to achieve by the first two equation₁And ρ₂Afterwards, latter two equation is substituted into, is tried to achieve Quality m of sample cylinder_{Empty barrel}With volume V_{Empty barrel}；

3. second part of mud shale sample is put into into sample cylinder, then space in housing is heated successively and evacuation at Reason, is then filled with helium into housing, and measures under air pressure conditions c and d respectively, and measurement process meets relational expression：

m_{R3 floats}=m_Float-V_Floatρ₃

m_{R4 floats}=m_Float-V_Floatρ₄

m_R3=m_{Empty barrel}+m_Sample-(V_{Empty barrel}+V_Sample)ρ₃

m_R4=m_{Empty barrel}+m_Sample-(V_{Empty barrel}+V_Sample)ρ₄

In above formula, m_{R3 floats}For helium air pressure be c, adsorption instrument be in the second gear when balance registration be in the first gear When balance registration difference；m_{R4 floats}For helium air pressure be d, adsorption instrument be in the second gear when balance registration be in first grade The difference of balance registration during position；ρ₃For density of the helium when air pressure is c；ρ₄For density of the helium when air pressure is d；m_R3For helium Balance registration when gas air pressure is c, adsorption instrument is in the first gear；m_R4For helium air pressure be d, adsorption instrument be in the first gear when Balance registration；m_SampleFor the quality of second part of mud shale sample；V_SampleFor the volume of second part of mud shale sample；

Density p of the helium when air pressure is c and d is tried to achieve by the first two equation₃And ρ₄After substitute into latter two equation, try to achieve Quality m of two parts of mud shale samples_SampleWith volume V_Sample；

4. again then the space evacuation in housing is filled with into a certain amount of methane into housing, and is measured, surveyed Amount meets relational expression：

m_{R floats}=m_Float-V_Floatρ

m_R=m_{Empty barrel}+m_Sample+m_{Absorption CH4}-(V_{Empty barrel}+V_Sample)ρ

In above formula, m_{R floats}For current methane gas pressure, adsorption instrument be in the second gear when balance registration be in first The difference of balance registration during gear；ρ is density of the methane under current gas pressure；m_RIt is in for the pressure of current methane gas, adsorption instrument Balance registration during the first gear；m_{Absorption CH4}For the quality of ADSORPTION STATE methane in second part of mud shale sample；

The density p of methane is calculated by previous formula, quality m that latter formula obtains ADSORPTION STATE methane is substituted into_{Absorption CH4}。

The step 4) in, carry out adsorbing amount n of the material of the ADSORPTION STATE methane of gained after phase volume amendment_{Absorption CH4}And matter Amount m_{Absorption CH4}Computation model be：

m_R=m_{Empty barrel}+m_Sample+m_{Absorption CH4}-(V_{Empty barrel}+V_Sample+V_Absorption)ρ。

Due to taking above technical scheme, it has advantages below to the present invention：1st, the present invention divides in one piece of mud shale sample Into two parts, a copy of it obtains the computation model of the amount of ADSORPTION STATE methane material by volumetric method adsorption isotherm experiment, another The computation model of the quality of ADSORPTION STATE methane is obtained by gravimetric method adsorption isotherm experiment, two model simultaneous solutions are finally obtained Obtain the precise measurements that methane adsorbs phase density on shale.2nd, amount and quality difference of the present invention to the material of ADSORPTION STATE methane Carry out adsorbing the amendment of phase volume, therefore computation model is more true and reliable so that the result that final survey calculation is obtained is more Plus accurately.3rd, the present invention is measured using experimental technique to the absorption phase density of methane, therefore the strong applicability of the method.

Description of the drawings

Fig. 1 is the structural representation of volumetric method isothermal adsorption instrument of the present invention；

Fig. 2 be gravimetric method isothermal adsorption instrument of the present invention be in the first gear when structural representation；

Fig. 3 be gravimetric method isothermal adsorption instrument of the present invention be in the second gear when structural representation.

Specific embodiment

The present invention is described in detail with reference to the accompanying drawings and examples.

The present invention proposes a kind of method that accurate test methane adsorbs phase density on shale, and it is comprised the following steps：

1) one piece of mud shale sample comminution is divided into two parts to 60~80 mesh.

2) volumetric method adsorption isotherm experiment is carried out to first part of mud shale sample, and obtains the content (first of ADSORPTION STATE methane Amount n of the material of alkane_{Absorption CH4}) computation model, detailed process is as follows：

1. as shown in figure 1, arranging one includes reference cell 1, sample cell 2, the first valve 3, the second valve 4, the first thermobarometer 5th, the volumetric method isothermal adsorption instrument of the second thermobarometer 6, helium source of the gas 7 and methane source of the gas 8, wherein, reference cell 1 connects respectively one and enters The outlet pipe 10 of air pipe 9 and, the first valve 3 is arranged on air inlet pipeline 9, and the second valve is arranged on outlet pipe 10, The end connection sample cell 2 of outlet pipe 10；First thermobarometer 5 is arranged in reference cell 1, and the second thermobarometer 6 is arranged on sample In pond 2；Helium source of the gas 7 and methane source of the gas 8 are connected to the initial end of air inlet pipeline 9 by pipeline.

2. it is put into system evacuation in sample cell 2 after first part of mud shale sample, closes the second valve 4, then beats The first valve 3 is opened, a certain amount of helium is filled with reference cell 1 using helium source of the gas, the first valve 3 is closed afterwards, treat reference After the temperature and pressure in pond 1 is stable, temperature T of helium in reference cell 1 is recorded_{Reference cell He}With pressure P_{Reference cell He}Value.According to gas shape State equation, has：

P_{Reference cell He}V_{Reference cell}=Z_{Reference cell He}n_{Reference cell He}RT_{Reference cell He} (1)

In above formula, V_{Reference cell}For the volume of reference cell 1；Z_{Reference cell He}For the imperfect gas shape body equation of helium in reference cell 1 Correction factor；n_{Reference cell He}The amount of the material of helium to be filled with reference cell 1；R is ideal gas constant.

3. the second valve 4 is opened, the helium in reference cell 1 enters sample cell 2, treats the He of reference cell 1 by outlet pipe 10 After the temperature and pressure of sample cell 2 is stablized, temperature T of helium in the system that reference cell 1 is constituted with sample cell 2 is recorded_{System He} With pressure P_{System He}Value.Now, according to the equation of gas state, have：

P_{System He}V_{System freedom}=Z_{System He}n_{System He}RT_{System He} (2)

In above formula, V_SystemThe resulting free sky of system after volume and deduction sample volume for reference cell 1 and sample cell 2 Between volume；Z_{System He}In the system being made up of reference cell 1 and sample cell 2 correction of the imperfect gas shape body equation of helium because Son；n_{System He}For the summation of the amount of the material of the helium in reference cell 1 and sample cell 2.

4. according to mass conservation law, that is, open the helium content before the second valve 4 in reference cell 1 and be equal to opening second Helium total content after valve 4 in reference cell 1 and sample cell 2, can obtain：

n_{Reference cell He}=n_{System He} (3)

Formula (1), formula (2) are substituted into into formula (3), is had

5. volume V of system free space can be tried to achieve by formula (4)_{System freedom}。

6. then the second valve 4 is closed by system evacuation again, the first valve 3 is opened, using methane source of the gas to A certain amount of methane is filled with reference cell 1, the first valve 3 is closed afterwards, after the temperature and pressure of reference cell 1 is stable, record Temperature T of methane in reference cell 1_{Reference cell CH4}With pressure P_{Reference cell CH4}Value.According to the equation of gas state, have：

P_{Reference cell CH4}V_{Reference cell}=Z_{Reference cell CH4}n_{Reference cell CH4}RT_{Reference cell CH4} (5)

In above formula, Z_{Reference cell CH4}For the correction factor of the imperfect gas shape body equation of methane in reference cell 1；n_{Reference cell CH4}To fill Enter the amount of the material of methane in reference cell 1.

7. the second valve 4 is opened, the methane in reference cell 1 enters sample cell 2, treats the He of reference cell 1 by outlet pipe 10 After the temperature and pressure of sample cell 2 is stablized, temperature T of methane in the system that reference cell 1 is constituted with sample cell 2 is recorded_{System CH4} With pressure P_{System CH4}Value.Now, according to the equation of gas state, have：

P_{System CH4}V_{System freedom}=Z_{System CH4}n_{The free CH4 of system}RT_{System CH4} (6)

In above formula, Z_{System CH4}The imperfect gas shape body equation of methane in the system being made up of reference cell 1 and sample cell 2 Correction factor；n_{The free CH4 of system}For the amount of the material of the methane of system free space.

8. according to mass conservation law, that is, open the methane content before the second valve 4 in reference cell 1 and be equal to opening second Methane content after valve 4 in system free space and the methane content of ADSORPTION STATE, can obtain：

n_{Reference cell CH4}=n_{The free CH4 of system}+n_{Absorption CH4} (7)

In above formula, n_{Absorption CH4}For the amount of the material of the methane of ADSORPTION STATE.

9. formula (5), formula (6) are substituted into into formula (7), can be obtained：

Formula (8) is the computation model of the amount of the material of ADSORPTION STATE methane, V therein_{System freedom}5. it is calculated by step.

3) gravimetric method adsorption isotherm experiment is carried out to second part of mud shale sample, and obtains the quality of ADSORPTION STATE methane m_{Absorption CH4}Computation model, detailed process is as follows：

One gravimetric method isothermal adsorption instrument (as shown in Figure 2 and Figure 3) is 1. set, and the top of the adsorption instrument is a magnetic suspension balance 11, bottom is a closed housing 12, and the suspended end in housing 12 installs a sample cylinder 13, is arranged in the top of sample cylinder 13 There is a float 14.The adsorption instrument has two gears to put, and when the first gear is placed in (as shown in Figure 2), balance weighs sample cylinder 13 Weight, balance registration be equal to sample cylinder 13 weight deduct buoyancy of the gas to sample cylinder 13；When the second gear is placed in (such as Shown in Fig. 3), balance weighs the weight of float 14 and sample cylinder 13, and balance registration is equal to the weight and float 14 of sample cylinder 13 Weight sum deducts sample cylinder 13 and the buoyancy suffered by float 14.So further, balance of the adsorption instrument in the second gear shows Number subtracts each other with the balance registration in the first gear, you can to obtain between the buoyancy suffered by the weight and float 14 of float 14 Difference.

2. nitrogen is filled with into housing 12, then measures under air pressure conditions a and b respectively and (control being filled with for nitrogen Amount can change air pressure conditions), the measurement meets relational expression：

m_{R1 floats}=m_Float-V_Floatρ₁ (9)

m_{R2 floats}=m_Float-V_Floatρ₂ (10)

m_R1=m_{Empty barrel}-V_{Empty barrel}ρ₁ (11)

m_R2=m_{Empty barrel}-V_{Empty barrel}ρ₂ (12)

In above formula, m_{R1 floats}For nitrogen pressure be a, adsorption instrument be in the second gear when balance registration be in the first gear When balance registration difference；m_{R2 floats}For nitrogen pressure be b, adsorption instrument be in the second gear when balance registration be in first grade The difference of balance registration during position；m_FloatFor the quality of float；V_FloatFor the volume of float；ρ₁For density of the nitrogen when air pressure is a； ρ₂For density of the nitrogen when air pressure is b；m_R1For nitrogen pressure be a, adsorption instrument be in the first gear when balance registration；m_R2For Balance registration when nitrogen pressure is b, adsorption instrument is in the first gear；m_{Empty barrel}For the quality of sample cylinder 13 (vacant)；V_{Empty barrel}For sample The volume of product cylinder 13.

Density p of the nitrogen under air pressure conditions a and b can be tried to achieve by formula (9), formula (10)₁And ρ₂；By ρ₁And ρ₂Substitution formula (11), formula (12) can try to achieve quality m of sample cylinder 13_{Empty barrel}With volume V_{Empty barrel}。

3. second part of mud shale sample is put into into sample cylinder 13, then space in housing 12 is heated successively (makes sample In the foreign gas that contains discharge) and evacuation process, helium is then filled with into housing, and respectively in air pressure conditions c With measure under d, measurement process meets relational expression：

m_{R3 floats}=m_Float-V_Floatρ₃ (13)

m_{R4 floats}=m_Float-V_Floatρ₄ (14)

m_R3=m_{Empty barrel}+m_Sample-(V_{Empty barrel}+V_Sample)ρ₃ (15)

m_R4=m_{Empty barrel}+m_Sample-(V_{Empty barrel}+V_Sample)ρ₄ (16)

In above formula, m_{R3 floats}For helium air pressure be c, adsorption instrument be in the second gear when balance registration be in the first gear When balance registration difference；m_{R4 floats}For helium air pressure be d, adsorption instrument be in the second gear when balance registration be in first grade The difference of balance registration during position；ρ₃For density of the helium when air pressure is c；ρ₄For density of the helium when air pressure is d；m_R3For helium Balance registration when gas air pressure is c, adsorption instrument is in the first gear；m_R4For helium air pressure be d, adsorption instrument be in the first gear when Balance registration；m_SampleFor the quality of second part of mud shale sample；V_SampleFor the volume of second part of mud shale sample.

By formula (13), formula (14) can in the hope of helium air pressure be c and d when density p₃And ρ₄；By ρ₃And ρ₄Substitution formula (15), formula (16) can try to achieve quality m of second part of mud shale sample_SampleWith volume V_Sample。

4. again then the space evacuation in housing 12 is filled with into a certain amount of methane into housing 12, and is surveyed Amount (single pressure condition measurement), measurement meets relational expression：

m_{R floats}=m_Float-V_Floatρ (17)

m_R=m_{Empty barrel}+m_Sample+m_{Absorption CH4}-(V_{Empty barrel}+V_Sample)ρ (18)

In above formula, m_{R floats}For current methane gas pressure, adsorption instrument be in the second gear when balance registration be in first The difference of balance registration during gear；ρ is density of the methane under current gas pressure；m_RIt is in for the pressure of current methane gas, adsorption instrument Balance registration during the first gear；m_{Absorption CH4}For the quality of ADSORPTION STATE methane in second part of mud shale sample.

The density p of methane can be obtained by formula (17), ρ is substituted into into formula (18) can obtain the quality of ADSORPTION STATE methane m_{Absorption CH4}。

4) to step 2) in resulting ADSORPTION STATE methane material amount n_{Absorption CH4}Computation model and step 3) in gained Quality m of the ADSORPTION STATE methane for arriving_{Absorption CH4}Computation model carry out adsorb phase volume amendment.For volumetric method, adsorb phase Volume V_AbsorptionPresence will occupy sectional interest free volume, it is considered to adsorb phase volume V_AbsorptionAfterwards formula (8) translates into formula (19)；It is right For gravimetric method, adsorb phase volume V_AbsorptionPresence will increase the buoyancy of gas, therefore formula (18) translates into formula (20)：

m_R=m_{Empty barrel}+m_Sample+m_{Absorption CH4}-(V_{Empty barrel}+V_Sample+V_Absorption)ρ (20)

5) according to the definition of the amount of material, have：

m_{Absorption CH4}=n_{Absorption CH4}M_CH4 (21)

In above formula, M_CH4For the molal weight of methane.

Simultaneous equations (19), (20), (21), can try to achieve m_{Absorption CH4}、n_{Absorption CH4}And V_Absorption。

6) according to the definition of density, methane can be tried to achieve and adsorbs phase density ρ on shale_AbsorptionExact value, i.e.,：

Absorption that can be in the hope of gases such as methane under different experimental conditions on shale using the method for the invention is mutually close Degree, on the basis of each experiment condition is summarized to adsorbing phase density affecting laws, you can obtain the absorption under different experimental conditions Phase density value.Now the test result that adsorption isotherm experiment is carried out individually with volumetric method or gravimetric method can be corrected.

For volumetric method, simultaneous formula (19) (21) and (22) can obtain：

The amount of the material of the ADSORPTION STATE methane after volumetric method correction can be tried to achieve according to formula (23).

And for gravimetric method, simultaneous formula (20) and (22) can obtain：

The present invention is only illustrated with above-described embodiment, and the structure of each part, set location and its connection all can be have Changed, on the basis of technical solution of the present invention, all individual part is carried out improvement according to the principle of the invention and equivalent Conversion, should not exclude outside protection scope of the present invention.

Claims (1)

1. a kind of method that accurate measurement methane adsorbs phase density on shale, comprises the following steps：

1) one piece of mud shale sample comminution is divided into two parts to 60~80 mesh；

2) volumetric method adsorption isotherm experiment is carried out to first part of mud shale sample, and obtains the amount of the material of ADSORPTION STATE methane n_{Absorption CH4}Computation model；

3) gravimetric method adsorption isotherm experiment is carried out to second part of mud shale sample, and obtains quality m of ADSORPTION STATE methane_{Absorption CH4}'s Computation model；

4) to step 2) in resulting ADSORPTION STATE methane material amount n_{Absorption CH4}Computation model and step 3) in it is resulting Quality m of ADSORPTION STATE methane_{Absorption CH4}Computation model carry out adsorb phase volume amendment, obtain the revised of ADSORPTION STATE methane The computation model of the amount of material and the computation model of quality；

5) according to the defined formula of the amount of material, with reference to step 4) in the amount of the revised material of ADSORPTION STATE methane that obtains The computation model of computation model and quality, obtains quality m of ADSORPTION STATE methane_{Absorption CH4}With volume V_Absorption；

6) according to the definition of density, try to achieve methane and adsorb phase density ρ on shale_AbsorptionExact value, i.e.,：

The step 2) in, amount n of the material of ADSORPTION STATE methane is set up by volumetric method adsorption isotherm experiment_{Absorption CH4}Calculating mould The process of type is as follows：

1. arranging one includes reference cell, sample cell, the first valve, the second valve, the first thermobarometer, the second thermobarometer, helium gas Source and the volumetric method isothermal adsorption instrument of methane source of the gas, wherein, reference cell connects respectively an air inlet pipeline and an outlet pipe, and first Valve is arranged on air inlet pipeline, and the second valve is arranged on outlet pipe, the end connection sample cell of outlet pipe；First is warm Pressure table is arranged in reference cell, and the second thermobarometer is arranged in sample cell；Helium source of the gas and methane source of the gas are connected by pipeline In the initial end of air inlet pipeline；

2. it is put into system evacuation in sample cell after first part of mud shale sample, closes the second valve, then opens first Valve, using helium source of the gas a certain amount of helium is filled with reference cell, and the first valve is closed afterwards, treat reference cell temperature and After pressure stability, temperature T of helium in reference cell is recorded_{Reference cell He}With pressure P_{Reference cell He}Value, according to the equation of gas state, have：

P_{Reference cell He}V_{Reference cell}=Z_{Reference cell He}n_{Reference cell He}RT_{Reference cell He}

In above formula, V_{Reference cell}For the volume of reference cell；Z_{Reference cell He}For the non-ideal gas behaviors equation of helium in reference cell correction because Son；n_{Reference cell He}The amount of the material of helium to be filled with reference cell；R is ideal gas constant；

3. the second valve is opened, the helium in reference cell enters sample cell by outlet pipe, treats the temperature of reference cell and sample cell After degree and pressure are stablized, temperature T of helium in the system that reference cell is constituted with sample cell is recorded_{System He}With pressure P_{System He}'s Value, now, according to the equation of gas state, has：

P_{System He}V_{System freedom}=Z_{System He}n_{System He}RT_{System He}

In above formula, V_{System freedom}Resulting system free space after volume and deduction sample volume for reference cell and sample cell Volume；Z_{System He}The correction factor of the non-ideal gas behaviors equation of helium in the system being made up of reference cell and sample cell； n_{System He}For the summation of the amount of the material of the helium in reference cell and sample cell；

4. according to mass conservation law, open the helium content before the second valve in reference cell and be equal to after the second valve of opening Helium total content in reference cell and sample cell, i.e.,：

n_{Reference cell He}=n_{System He}

By step 2. and 3. in resulting equation substitute into above formula, obtain

5. by step, 4. gained formula tries to achieve volume V of system free space_{System freedom}；

6. again to system evacuation, then by the second valve closing, the first valve is opened, using methane source of the gas to reference cell A certain amount of methane is inside filled with, the first valve is closed afterwards, after the temperature and pressure of reference cell is stable, first in record reference cell Temperature T of alkane_{Reference cell CH4}With pressure P_{Reference cell CH4}Value, according to the equation of gas state, have：

P_{Reference cell CH4}V_{Reference cell}=Z_{Reference cell CH4}n_{Reference cell CH4}RT_{Reference cell CH4}

In above formula, Z_{Reference cell CH4}For the correction factor of the non-ideal gas behaviors equation of methane in reference cell；n_{Reference cell CH4}To be filled with ginseng Than the amount of the material of the methane in pond；

7. the second valve is opened, the methane in reference cell enters sample cell by outlet pipe, treats the temperature of reference cell and sample cell After degree and pressure are stablized, temperature T of methane in the system that reference cell is constituted with sample cell is recorded_{System CH4}With pressure P_{System CH4}'s Value, now, according to the equation of gas state, has：

P_{System CH4}V_{System freedom}=Z_{System CH4}n_{The free CH4 of system}RT_{System CH4}

In above formula, Z_{System CH4}The correction of the non-ideal gas behaviors equation of methane in the system being made up of reference cell and sample cell The factor；n_{The free CH4 of system}For the amount of the material of the methane of system free space.

8. according to mass conservation law, open the methane content before the second valve in reference cell and be equal to after the second valve of opening The methane content of methane content and ADSORPTION STATE in system free space, i.e.,：

n_{Reference cell CH4}=n_{The free CH4 of system}+n_{Absorption CH4}

In above formula, n_{Absorption CH4}For the amount of the material of the methane of ADSORPTION STATE；

9. by step 6. and 7. in resulting equation substitute into step 8. in the formula of gained, obtain the material of ADSORPTION STATE methane Amount n_{Absorption CH4}Computation model：

V in formula_{System freedom}5. it is calculated by step；

The step 3) in, quality m of ADSORPTION STATE methane is set up by gravimetric method adsorption isotherm experiment_{Absorption CH4}Computation model Process is as follows：

1. one gravimetric method isothermal adsorption instrument is set, and the top of the adsorption instrument is a magnetic suspension balance, and bottom is a closed housing, Suspended end in housing installs a sample cylinder, and a float is provided with above sample cylinder；The adsorption instrument is provided with two gears, When the first gear is placed in, balance weighs the weight of sample cylinder, and balance registration is equal to the weight of sample cylinder and deducts gas to sample The buoyancy of cylinder；When the second gear is placed in, balance weighs the weight of float and sample cylinder, and balance registration is equal to the weight of sample cylinder The buoyancy suffered by sample cylinder and float is deducted with the weight sum of float；Further, balance of the adsorption instrument in the second gear Registration is subtracted each other with the balance registration in the first gear, that is, obtain the difference between the buoyancy suffered by the weight and float of float；

2. nitrogen is filled with into housing, is then measured under air pressure conditions a and b respectively, measurement meets following relational expression：

m_{R1 floats}=m_Float-V_Floatρ₁

m_{R2 floats}=m_Float-V_Floatρ₂

m_R1=m_{Empty barrel}-V_{Empty barrel}ρ₁

m_R2=m_{Empty barrel}-V_{Empty barrel}ρ₂

In above formula, m_{R1 floats}For nitrogen pressure be a, adsorption instrument be in the second gear when balance registration with the first gear when The difference of balance registration；m_{R2 floats}For nitrogen pressure be b, adsorption instrument be in the second gear when balance registration with the first gear when Balance registration difference；m_FloatFor the quality of float；V_FloatFor the volume of float；ρ₁For density of the nitrogen when air pressure is a；ρ₂For Density of the nitrogen when air pressure is b；m_R1For nitrogen pressure be a, adsorption instrument be in the first gear when balance registration；m_R2For nitrogen Balance registration when gas air pressure is b, adsorption instrument is in the first gear；m_{Empty barrel}For the quality of sample cylinder；V_{Empty barrel}For the volume of sample cylinder；

Density p of the nitrogen under air pressure conditions a and b is tried to achieve by the first two equation₁And ρ₂Afterwards, latter two equation is substituted into, sample is tried to achieve Quality m of cylinder_{Empty barrel}With volume V_{Empty barrel}；

3. second part of mud shale sample is put into into sample cylinder, then space in housing is heated successively and evacuation process, so It is filled with helium in backward housing, and measures under air pressure conditions c and d respectively, measurement process meets relational expression：

m_{R3 floats}=m_Float-V_Floatρ₃

m_{R4 floats}=m_Float-V_Floatρ₄

m_R3=m_{Empty barrel}+m_Sample-(V_{Empty barrel}+V_Sample)ρ₃

m_R4=m_{Empty barrel}+m_Sample-(V_{Empty barrel}+V_Sample)ρ₄

In above formula, m_{R3 floats}For helium air pressure be c, adsorption instrument be in the second gear when balance registration with the first gear when The difference of balance registration；m_{R4 floats}For helium air pressure be d, adsorption instrument be in the second gear when balance registration with the first gear when Balance registration difference；ρ₃For density of the helium when air pressure is c；ρ₄For density of the helium when air pressure is d；m_R3For helium gas Press for c, adsorption instrument be in the first gear when balance registration；m_R4For helium air pressure be d, adsorption instrument be in the first gear when Balance registration；m_SampleFor the quality of second part of mud shale sample；V_SampleFor the volume of second part of mud shale sample；

Density p of the helium when air pressure is c and d is tried to achieve by the first two equation₃And ρ₄After substitute into latter two equation, try to achieve second part Quality m of mud shale sample_SampleWith volume V_Sample；

4. again then the space evacuation in housing is filled with into a certain amount of methane into housing, and is measured, measurement is full Sufficient relational expression：

m_{R floats}=m_Float-V_Floatρ

m_R=m_{Empty barrel}+m_Sample+m_{Absorption CH4}-(V_{Empty barrel}+V_Sample)ρ

In above formula, m_{R floats}For current methane gas pressure, adsorption instrument be in the second gear when balance registration with the first gear when Balance registration difference；ρ is density of the methane under current gas pressure；m_RFirst grade is in for the pressure of current methane gas, adsorption instrument Balance registration during position；m_{Absorption CH4}For the quality of ADSORPTION STATE methane in second part of mud shale sample；

The density p of methane is calculated by previous formula, quality m that latter formula obtains ADSORPTION STATE methane is substituted into_{Absorption CH4}；

The step 4) in, carry out adsorbing amount n of the material of the ADSORPTION STATE methane of gained after phase volume amendment_{Absorption CH4}And quality m_{Absorption CH4}Computation model be：

m_R=m_{Empty barrel}+m_Sample+m_{Absorption CH4}-(V_{Empty barrel}+V_Sample+V_Absorption)ρ。