CN105628575A - Shale property determination method and device and shale property determinator - Google Patents

Abstract

The invention discloses a shale property determination method and device and a shale property determinator and belongs to the technical field of measurement technologies. The method comprises acquiring n pressure values which are gas pressure values at two ends of a shale sample and are recorded at preset time intervals in diffusion in the shale sample, calculating n corresponding concentration values according to the n pressure values, solving a one-dimensional diffusion equation according to the n concentration values to obtain a diffusion coefficient D of the shale sample, wherein the diffusion coefficient D is used for showing a diffusion degree of the gas in the shale sample, and calculating permeability k of the shale sample according to the formula of k=D*mu*phi*beta<t> . The determination method solves the problem that the existing determination method produces an inaccurate determination result because of no consideration of shale gas non-darcy flow characteristics and adsorbed gas-caused influence in shale permeability determination, and fully improves determination result accuracy.

Description

Shale character assay method, device and shale character analyzer

Technical field

The present invention relates to field of measuring technique, particularly to a kind of shale character assay method, device and shale character analyzer.

Background technology

Shale gas is a kind of unconventional gas resource being stored in rammell, its have have a very wide distribution, the advantage such as production life of well length and production cycle length, there is good application prospect.

Shale gas fluid ability in rammell be evaluate shale gas can the key factor of the economic exploitation. Wherein, conventional fluid ability evaluating is permeability. In the related, darcy steady flow method is generally adopted to measure shale permeability. By measuring the flow of the gas passing through shale samples under certain pressure, then calculate the permeability of shale samples according to darcy straight line diafiltration law.

It addition, pertinent literature it is also proposed employing pulse attenuation method measures shale permeability. Mainly include core post pulse attenuation method, granule pulse attenuation method and degassing method these three assay method. Wherein, core post pulse attenuation method is comparatively strict to the requirement of experimental apparatus and shale samples, although possesses higher mensuration effect and precision, but also needs further research in Mathematical treatment; Shale samples is reduced to irregular figure by granule pulse attenuation method, destroys pore structure, and measurement result has certain impact; Degassing method is only applicable to the test of on-the-spot sealed coring, measures examination to shale reservoir gas-bearing relevant, and precision is not high.

In the process realizing the present invention, inventor have found that above-mentioned technology at least there is problems in that gas seepage flow in shale exists non-Darcy flow feature, now the permeability of application darcy straight line seepage flow law calculating shale necessarily causes the inaccurate problem of measurement result. It addition, the various assay methods that above-mentioned technology relates to, all do not consider the impact of adsorbed gas when measuring the permeability of shale, cause the inaccurate problem of measurement result.

Summary of the invention

The assay method related to solve above-mentioned technology does not consider the Non-Darcy's flow dynamic characteristic of shale gas and the impact of adsorbed gas when measuring the permeability of shale, the inaccurate problem of measurement result caused, embodiments provides a kind of shale character assay method, device and shale character analyzer. Described technical scheme is as follows:

First aspect, it is provided that a kind of shale character assay method, described method includes:

Obtain n group force value, described n group force value is in the process that gas spreads in shale samples, force value every the described shale samples two ends of predetermined time interval record, for each group of force value, described force value includes the pressure value P being placed with the entrance point of the rock core fastener of described shale samples_inPressure value P with the port of export_out, n >=2 and n are integer;

Calculate the n group concentration value of correspondence according to described n group force value, for each group of concentration value, described concentration value includes the concentration value N of described entrance point_inConcentration value N with the described port of export_out;

Solving One-dimensional Diffusion Equation according to described n group concentration value and obtain the diffusion coefficient D of described shale samples, described diffusion coefficient D is for reflecting gas diffusion in described shale samples;

Following formula is used to calculate the permeability k of described shale samples:

K=D �� �� ��_t;

Wherein, described D represents described diffusion coefficient (m²/ s); Described �� represents fluid viscosity (Pa s); Described �� represents the effecive porosity (%) of described shale samples; Described ��_tRepresent the coefficient of compressibility (Pa under initial pore pressure^-1)��

Optionally, described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;\mathrm{0,0}<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);

Or,

Described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2\frac{\&PartialD;Q}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;0,0<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);The increase amount of expression adsorbed gas content corresponding to moment t; Described ��₁Represent the density (kg/m of described shale samples³); Described ��₂Represent gas density (kg/m³)��

Optionally, the following formula of described use also includes before calculating the permeability k of described shale samples:

Following formula is used to calculate the effecive porosity �� of described shale samples:

$\mathrm{\&phi;}=\frac{\frac{Z_2{P}_1{V}_1}{Z_1{P}_2}-V_1-V_x}{\mathrm{SL}};$

Wherein, described S represents the sectional area (m of described shale samples²); Described L represents the length (m) of described shale samples; Described P₁Represent pulsating pressure (MPa); Described P₂Represent balance pressure (MPa); Described Z₁Represent that gas is in pressure P₁Under compressibility factor; Described Z₂Represent that gas is in pressure P₂Under compressibility factor; Described V₁Represent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³); Described V_xRepresent the volume (m of pipeline between described upstream gas container, described upstream inlet valve, described rock core fastener and described downstream inlet valve³)��

Optionally, described method also includes:

Following formula is used to calculate the adsorbed gas content Q of described shale samples_n:

$Q_n=\frac{V_n}{m};$

Wherein, described Q_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that the described shale samples of unit mass adsorbs³/ kg); Described m represents the quality (kg) of described shale samples; Described V_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that described shale samples adsorbs³);Described T₀Representing room temperature (DEG C), described T represents experimental temperature (DEG C), described P₀Represent normal atmosphere (MPa), described V_hRepresent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³), described V_��Represent the pore volume (m of described rock core fastener³), described P_nRepresent the n-th pulsating pressure (MPa), described P_n ^*Represent the n-th adsorption equilibrium pressure (MPa), described Z_nRepresent that gas is in pressure P_nUnder compressibility factor, described Z_n ^*Represent that gas is in pressure P_n ^*Under compressibility factor; As n=1, $V_1=\frac{T_0}{T{P}_0}(\frac{P_1{V}_h}{Z_1}-\frac{P_1^{*}{V}_h}{Z_1^{*}}-\frac{P_1^{*}{V}_{\mathrm{\&phi;}}}{Z_1^{*}}).$

Second aspect, it is provided that a kind of shale character determinator, described device includes:

Pressure acquisition module, for obtaining n group force value, described n group force value is in the process that gas spreads in shale samples, force value every the described shale samples two ends of predetermined time interval record, for each group of force value, described force value includes the pressure value P being placed with the entrance point of the rock core fastener of described shale samples_inPressure value P with the port of export_out, n >=2 and n are integer;

Concentration calculation module, for calculating the n group concentration value of correspondence according to described n group force value, for each group of concentration value, described concentration value includes the concentration value N of described entrance point_inConcentration value N with the described port of export_out;

Diffusion coefficient computing module, obtains the diffusion coefficient D of described shale samples for solving One-dimensional Diffusion Equation according to described n group concentration value, and described diffusion coefficient D is for reflecting gas diffusion in described shale samples;

Computing permeability module, for using following formula to calculate the permeability k of described shale samples:

K=D �� �� ��_t;

Wherein, described D represents described diffusion coefficient (m²/ s); Described �� represents fluid viscosity (Pa s); Described �� represents the effecive porosity (%) of described shale samples; Described ��_tRepresent the coefficient of compressibility (Pa under initial pore pressure^-1)��

Optionally, described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;\mathrm{0,0}<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);

Or,

Described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2\frac{\&PartialD;Q}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;0,0<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);The increase amount of expression adsorbed gas content corresponding to moment t; Described ��₁Represent the density (kg/m of described shale samples³); Described ��₂Represent gas density (kg/m³)��

Optionally, described device also includes:

Porosity calculation module, for using following formula to calculate the effecive porosity �� of described shale samples:

$\mathrm{\&phi;}=\frac{\frac{Z_2{P}_1{V}_1}{Z_1{P}_2}-V_1-V_x}{\mathrm{SL}};$

Wherein, described S represents the sectional area (m of described shale samples²); Described L represents the length (m) of described shale samples; Described P₁Represent pulsating pressure (MPa); Described P₂Represent balance pressure (MPa); Described Z₁Represent that gas is in pressure P₁Under compressibility factor; Described Z₂Represent that gas is in pressure P₂Under compressibility factor; Described V₁Represent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³); Described V_xRepresent the volume (m of pipeline between described upstream gas container, described upstream inlet valve, described rock core fastener and described downstream inlet valve³)��

Optionally, described device also includes:

Adsorbed gas computing module, for using following formula to calculate the adsorbed gas content Q of described shale samples_n:

$Q_n=\frac{V_n}{m};$

Wherein, described Q_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that the described shale samples of unit mass adsorbs³/ kg); Described m represents the quality (kg) of described shale samples; Described V_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that described shale samples adsorbs³);Described T₀Representing room temperature (DEG C), described T represents experimental temperature (DEG C), described P₀Represent normal atmosphere (MPa), described V_hRepresent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³), described V_��Represent the pore volume (m of described rock core fastener³), described P_nRepresent the n-th pulsating pressure (MPa), described P_n ^*Represent the n-th adsorption equilibrium pressure (MPa), described Z_nRepresent that gas is in pressure P_nUnder compressibility factor, described Z_n ^*Represent that gas is in pressure P_n ^*Under compressibility factor; As n=1, $V_1=\frac{T_0}{T{P}_0}(\frac{P_1{V}_h}{Z_1}-\frac{P_1^{*}{V}_h}{Z_1^{*}}-\frac{P_1^{*}{V}_{\mathrm{\&phi;}}}{Z_1^{*}}).$

The third aspect, providing a kind of shale character analyzer, described shale character analyzer includes: upstream gas container, upstream inlet valve, for placing the rock core fastener of shale samples, downstream inlet valve, gas downstream container, upstream hydraulic pump, confined pressure hydraulic pump, downstream hydraulic pump, pressure transducer, differential pressure pickup, confined pressure intake valve, atmospheric valve, calorstat, timer and computing equipment;

Wherein, the entrance point of described rock core fastener passes sequentially through the first valve of described upstream inlet valve, the second valve of described upstream inlet valve is connected with the first end of described upstream gas container; The port of export of described rock core fastener passes sequentially through the first valve of described downstream inlet valve, the second valve of described downstream inlet valve is connected with the first end of described gas downstream container; Described rock core fastener, described upstream gas container and described gas downstream container are installed in described calorstat; Described upstream hydraulic pump is connected with the 3rd valve of described upstream inlet valve by the first pipeline, and described downstream hydraulic pump is connected with the 3rd valve of described downstream inlet valve by the second pipeline; 4th valve of described upstream inlet valve is connected with the 4th valve of described downstream inlet valve by the 3rd pipeline; 5th valve of described upstream inlet valve is connected through the 5th valve of described differential pressure pickup with described downstream inlet valve; Described confined pressure hydraulic pump is connected with the sidewall of described rock core fastener through described confined pressure intake valve; Second end of described upstream gas container is connected with described pressure transducer, and the second end of described gas downstream container is connected with described atmospheric valve; Described pressure transducer, described differential pressure pickup are connected with described computing equipment respectively with described timer;

Described computing equipment, including the shale character determinator as described in second aspect.

The technical scheme that the embodiment of the present invention provides has the benefit that

Obtain the diffusion coefficient of shale samples by solving the One-dimensional Diffusion Equation pre-build, and then try to achieve the permeability of shale samples according to diffusion coefficient; Solve the assay method that background technology relates to and do not consider the Non-Darcy's flow dynamic characteristic of shale gas and the impact of adsorbed gas when measuring the permeability of shale, the inaccurate problem of measurement result caused; Substantially increase the accuracy of measurement result.

Accompanying drawing explanation

In order to be illustrated more clearly that the technical scheme in the embodiment of the present invention, below the accompanying drawing used required during embodiment is described is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the structural representation of the shale character analyzer that one embodiment of the invention provides;

Fig. 2 is the method flow diagram of the shale character assay method that one embodiment of the invention provides;

Fig. 3 A is the method flow diagram of the shale character assay method that another embodiment of the present invention provides;

Fig. 3 B is the schematic diagram that the gas involved by another embodiment of the present invention spreads in shale samples;

Fig. 4 is the block diagram of the shale character determinator that one embodiment of the invention provides;

Fig. 5 is the block diagram of the shale character determinator that another embodiment of the present invention provides.

Detailed description of the invention

For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail.

Refer to Fig. 1, it illustrates the structural representation of shale character analyzer that one embodiment of the invention provides, this shale character analyzer includes: upstream gas container 101, upstream inlet valve 102, for placing the rock core fastener 103 of shale samples, downstream inlet valve 104, gas downstream container 105, upstream hydraulic pump 106, confined pressure hydraulic pump 107, downstream hydraulic pump 108, pressure transducer 109, differential pressure pickup 110, confined pressure intake valve 111, atmospheric valve 112, calorstat 113, timer 114 and computing equipment 115. Wherein:

The entrance point 103a of rock core fastener 103 passes sequentially through the first valve 102a of upstream inlet valve 102, the second valve 102b of upstream inlet valve 102 is connected with the first end of upstream gas container 101; The port of export 103b of rock core fastener 103 passes sequentially through the first valve 104a of downstream inlet valve 104, the second valve 104b of downstream inlet valve 104 is connected with the first end of gas downstream container 105.

Rock core fastener 103 is used for placing shale samples. Under normal conditions, shale samples is column, and diameter is between 2.5cm-10cm, and length is between 2cm-20cm.

Rock core fastener 103, upstream gas container 101 and gas downstream container 105 are installed in calorstat 113. The maximum temperature of calorstat 113 may be set to 120 DEG C.

Upstream hydraulic pump 106 is connected with the 3rd valve 102c of upstream inlet valve 102 by the first pipeline, and downstream hydraulic pump 108 is connected with the 3rd valve 104c of downstream inlet valve 104 by the second pipeline. Upstream hydraulic pump 106 and downstream hydraulic pump 108 are for being respectively pressed into experimental gas in upstream gas container 101 and gas downstream container 105. The CH that experimental gas can select purity to be 99.9%₄(methane), purity are the CO of 99.9%₂(carbon dioxide), purity are the N of 99.9%₂(nitrogen) or the He (helium) that purity is 99.9%. Hydraulic pump water is generally selected distilled water.

4th valve 102d of upstream inlet valve 102 is connected with the 4th valve 104d of downstream inlet valve 104 by the 3rd pipeline. 5th valve 102e of upstream inlet valve 102 is connected with the 5th valve 104e of downstream inlet valve 104 through differential pressure pickup 110. Differential pressure pickup 110 is for gathering the pressure differential between the entrance point 103a of rock core fastener 103 and the port of export 103b of rock core fastener 103. Upstream inlet valve 102 and downstream inlet valve 104 can select six-way valve.

Confined pressure hydraulic pump 107 is connected through the sidewall of confined pressure intake valve 111 with rock core fastener 103. Confined pressure hydraulic pump 107 for providing certain confined pressure and axial compressive force to shale samples.

Second end of upstream gas container 101 is connected with pressure transducer 109, and the second end of gas downstream container 105 is connected with atmospheric valve 112. Pressure transducer 109 is for gathering the force value of the entrance point 103a of rock core fastener 103.

Pressure transducer 109, differential pressure pickup 110 are connected with computing equipment 115 respectively with timer 114. Such as, pressure transducer 109, differential pressure pickup 110 and timer 114 can be connected with computing equipment 115 respectively through data wire. Computing equipment 115 is generally computer, it is possible to be desk computer, or portable computer on knee. Computing equipment 115 can include below figure 4 or the shale character determinator of embodiment illustrated in fig. 5 offer, and this shale character determinator is configured to the shale character assay method performing below figure 2 or the offer of Fig. 3 A illustrated embodiment.

Additionally, in the embodiment that other is possible, pressure transducer 109 or differential pressure pickup 110 can be replaced by another pressure transducer, and this another pressure transducer is connected with gas downstream container 105, for gathering the force value of the port of export 103b of rock core fastener 103.

In the technical scheme that the embodiment of the present invention provides, the parameters such as the porosity of shale samples, permeability, free gas content and adsorbed gas content can be measured by the analyzer of shale character shown in Fig. 1.

Specifically, when measuring the porosity of shale samples, it is possible to include following several experimental procedure:

(1) diameter d, length L and the quality m of shale samples are measured;

(2) dead volume V is measured_x, dead volume V_xVolume including the pipeline between upstream gas container 101, upstream inlet valve 102, rock core fastener 103 and downstream inlet valve 104;

(3) structure according to Fig. 1 connects each instrument, and is put into by shale samples in rock core fastener 103;

(4) all valves are closed, by confined pressure hydraulic pump 107 to the shale samples certain confined pressure of loading and axial compressive force;

(5) open the second valve 102b and the three valve 102c of upstream inlet valve 102, by being filled with experimental gas in upstream hydraulic pump 106 upstream gas container 101, and reach predetermined threshold P in the registration of pressure transducer 109₁Time, close the 3rd valve 102c of upstream inlet valve 102;

(6) the first valve 102a of upstream inlet valve 102 is opened so that experimental gas spreads through shale samples, treats that the registration of pressure transducer 109 is steady state value P₂Time, the registration P of record pressure transducer 109₂��

When measuring the permeability of shale samples, it is possible to include following several experimental procedure:

(1) diameter d, length L and the quality m of shale samples are measured;

(2) dead volume V is measured_x, dead volume V_xVolume including the pipeline between upstream gas container 101, upstream inlet valve 102, rock core fastener 103 and downstream inlet valve 104;

(3) structure according to Fig. 1 connects each instrument, and is put into by shale samples in rock core fastener 103;

(4) all valves are closed, by confined pressure hydraulic pump 107 to the shale samples certain confined pressure of loading and axial compressive force;

(5) open the second valve 102b and the three valve 102c of upstream inlet valve 102 and the second valve 104b and the three valve 104c of downstream inlet valve 104, be filled with a certain amount of experimental gas respectively through in upstream hydraulic pump 106 and downstream hydraulic pump 108 upstream gas container 101 and gas downstream container 105;

(6) the 3rd valve 102c of upstream inlet valve 102 and the 3rd valve 104c of downstream inlet valve 104 is closed, and open the first valve 102a of upstream inlet valve 102, first valve 104a of the 4th valve 102d and the five valve 102e and downstream inlet valve 104, 4th valve 104d and the five valve 104e, experimental gas is spread, at upstream gas container 101, gas downstream container 105 and shale samples sufficiently achieve balance, when the registration of differential pressure pickup 110 is 0MPa, close the first valve 102a of upstream inlet valve 102, 4th valve 104d of the 4th valve 102d and downstream inlet valve 104,

(7) the 3rd valve 102c of upstream inlet valve 102 is opened, a pulsating pressure set in advance is applied by upstream hydraulic pump 106 upstream gas container 101, close the 3rd valve 102c of upstream inlet valve 102, and record pressure transducer 109 and the registration of differential pressure pickup 110;

(8) the first valve 102a of upstream inlet valve 102 is opened, under the effect of the concentration difference caused in pressure differential, experimental gas is spread by shale samples, every the registration of predetermined time interval record pressure transducer 109 and differential pressure pickup 110, until the registration of differential pressure pickup 110 is 0MPa.

When measuring the adsorbed gas content of shale samples, it is possible to include following several experimental procedure:

(1) structure according to Fig. 1 connects each instrument, and is put into by shale samples in rock core fastener 103;

(2) all valves are closed, by confined pressure hydraulic pump 107 to the shale samples certain confined pressure of loading and axial compressive force;

(3) the second valve 102b and the three valve 102c of upstream inlet valve 102 is opened, by being filled with a certain amount of experimental gas in upstream hydraulic pump 106 upstream gas container 101, and record the registration P1, the 3rd valve 102c of closedown upstream inlet valve 102 of pressure transducer 109;

(4) the first valve 102a of upstream inlet valve 102 is opened so that experimental gas spreads through shale samples, treats that the registration of pressure transducer 109 is steady state value P₁ ^*Time, the registration P of record pressure transducer 109₁ ^*, close the first valve 102a of upstream inlet valve 102;

(5) repeat the above steps (3) and (4), record P₂��P₂ ^*������P_n��P_n ^*, until adsorption equilibrium pressure P_n ^*Reach experiment maximum pressure set in advance;

Optionally, may also include following several desorption experiment step after step (5):

(6) pressure in rock core fastener 103 is reduced, by pressure before pressure transducer 109 record balance;

(7) when pressure balance, record desorbing balance pressure, record the time spent by above-mentioned pressure equalization process by timer 114 simultaneously;

(8) repeat the above steps (6) and (7), until desorbing balance pressure reaches experiment minimum pressure set in advance.

It should be noted is that: in any of the above-described experiment, after structure according to Fig. 1 connects each instrument, it is necessary to the air-tightness of checking experiment device; It addition, also need whole experimental provision evacuation, it is ensured that there is no inclusion of air in each instrument, reduce experimental error.

In the process realizing the present invention, inventors have discovered that gas flowing in shale meets diffusion law, under the concentration difference that pressure differential causes, there is one-dimensional diffusion in gas in shale. It is therefore proposed that diffusion coefficient evaluates gas fluid ability in shale. Diffusion coefficient indicates that the physical quantity of gas diffusion, and diffusion coefficient refers to along dispersal direction, and when unit time per unit Concentraton gradient, perpendicular through the quality of unit are institute diffusion gas, unit is m²/ s or cm²/ s. Further, the permeability of shale is solved according to diffusion coefficient, it is possible to make measurement result more accurate.

Below, by several embodiments technical scheme provided by the invention will be described in detail and illustrate:

Refer to Fig. 2, it illustrates the method flow diagram of the shale character assay method that one embodiment of the invention provides, the present embodiment is applied in the computing equipment 115 in the analyzer of shale character shown in Fig. 1 to be illustrated with this shale character assay method. This shale character assay method may include steps of:

Step 202, obtain n group force value, this n group force value is in the process that gas spreads in shale samples, force value every the shale samples two ends of predetermined time interval record, for each group of force value, this group force value includes the pressure value P being placed with the entrance point of the rock core fastener of shale samples_inPressure value P with the port of export_out, n >=2 and n are integer.

Step 204, calculates the n group concentration value of correspondence according to above-mentioned n group force value, and for each group of concentration value, this group concentration value includes the concentration value N of entrance point_inConcentration value N with the port of export_out��

Step 206, solves One-dimensional Diffusion Equation according to above-mentioned n group concentration value and obtains the diffusion coefficient D of shale samples, and this diffusion coefficient D is for reflecting gas diffusion in shale samples.

Step 208, uses following formula to calculate the permeability k of shale samples:

K=D �� �� ��_t;

Wherein, D represents diffusion coefficient (m²/ s); �� represents fluid viscosity (Pa s); �� represents the effecive porosity (%) of shale samples; ��_tRepresent the coefficient of compressibility (Pa under initial pore pressure^-1)��

In sum, the shale character assay method that the present embodiment provides, obtain the diffusion coefficient of shale samples by solving the One-dimensional Diffusion Equation pre-build, and then try to achieve the permeability of shale samples according to diffusion coefficient; Solve the assay method that background technology relates to and do not consider the Non-Darcy's flow dynamic characteristic of shale gas and the impact of adsorbed gas when measuring the permeability of shale, the inaccurate problem of measurement result caused; Substantially increase the accuracy of measurement result.

Refer to Fig. 3 A, it illustrates the method flow diagram of the shale character assay method that another embodiment of the present invention provides, the present embodiment is applied in the computing equipment 115 in the analyzer of shale character shown in Fig. 1 to be illustrated with this shale character assay method. This shale character assay method may include steps of:

Step 301, calculates the effecive porosity �� of shale samples:

$\mathrm{\&phi;}=\frac{\frac{Z_2{P}_1{V}_1}{Z_1{P}_2}-V_1-V_x}{\mathrm{SL}};$

Wherein, S represents the sectional area (m of shale samples²); L represents the length (m) of shale samples; P₁Represent pulsating pressure (MPa); P₂Represent balance pressure (MPa); Z₁Represent that gas is in pressure P₁Under compressibility factor; Z₂Represent that gas is in pressure P₂Under compressibility factor; V₁Represent the upstream gas volume of a container (m being connected with the entrance point of rock core fastener³); V_xRepresent the volume (m of upstream gas container, upstream inlet valve, pipeline between rock core fastener and downstream inlet valve³)��

First, Boyle's law the active porosity volume V of shale samples is calculated_p:

Z₂P₁V₁=Z₁P₂(V₁+V_x+V_p);

Wherein, P₁Represent pulsating pressure (MPa) namely the force value of record in the experimental procedure of the porosity at said determination shale samples (5); P₂Represent balance pressure (MPa) namely the force value of record in the experimental procedure of the porosity at said determination shale samples (6); Z₁Represent that gas is in pressure P₁Under compressibility factor; Z₂Represent that gas is in pressure P₂Under compressibility factor; V₁Represent the upstream gas volume of a container (m being connected with the entrance point of rock core fastener³); V_xRepresent the volume (m of upstream gas container, upstream inlet valve, pipeline between rock core fastener and downstream inlet valve³), also referred to as dead volume; V_pRepresent the active porosity volume (m of shale samples³)��

Can be derived by above formula: active porosity volume

The effecive porosity �� of shale samples is equal to the active porosity volume V of shale samples_pWith the ratio of the volume V of shale samples, namely:

$\mathrm{\&phi;}=\frac{V_p}{V}=\frac{\frac{Z_2{P}_1{V}_1}{Z_1{P}_2}-V_1-V_x}{\mathrm{SL}};$

Wherein, S represents the sectional area (m of shale samples²); L represents the length (m) of shale samples.

Optionally, when the cylindrical sample of shale samples is diameter to be d, length be L, due to the sectional area of shale samples $S=\frac{{\mathrm{\&pi;d}}^2}{4},$ So $\mathrm{\&phi;}=\frac{{4V}_p}{\mathrm{\&pi;}{d}^{2}L}.$

Before calculating the permeability k of shale samples, initially set up mathematical model. As shown in Figure 3 B, it illustrates the schematic diagram that gas spreads in shale samples. Experimental procedure incorporated by reference to the permeability of reference said determination shale samples, when gas in upstream gas container, gas downstream container and shale samples sufficiently achieves balance, one pressure pulse set in advance acts in upstream gas container, making gas form one-dimensional diffusion in shale samples, Fig. 3 B arrow direction represents gas dispersal direction. In whole diffusion process, pressure in upstream gas container is gradually lowered, pressure in gas downstream container gradually rises, the pressure differential at shale samples two ends is gradually reduced, when gas in upstream gas container, gas downstream container and shale samples reaches to balance again, the pressure differential at shale samples two ends becomes 0MPa.

With function N, (x, t) represents the object G concentration value at position x and moment t, the quality of institute's diffusate in this concentration value representation unit volume. Owing to shale samples is placed in rock core fastener, there is certain confined pressure, shale samples and rock core fastener close contact, it is believed that shale samples side surface part produces diffusion. Therefore, gas diffusing phenomenon in shale samples meet one-dimensional diffusion, derive gas by imfinitesimal method and the principle of mass conservation and the mathematical model of one-dimensional diffusion occurs in shale samples.

Owing to shale has characterization of adsorption, when considering adsorbed gas, the gas part flowing into shale samples makes concentration inside increase, and another part makes adsorbed gas content increase, and thus can set up One-dimensional Diffusion Equation:

$\frac{\&PartialD;N}{\&PartialD;t}+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2\frac{\&PartialD;Q}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;0,0<x<L);$

Wherein, L represents the length (m) of shale samples; N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);The increase amount of expression adsorbed gas content corresponding to moment t; ��₁Represent the density (kg/m of shale samples³); ��₂Represent gas density (kg/m³)��

It addition, if initial balance pressure design is sufficiently large, under the effect of pulsating pressure, the increase amount of adsorbed gas content will be very little, it is possible to ignores, then, when being left out adsorbed gas, One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;\mathrm{0,0}<x<L);$

Wherein, L represents the length (m) of shale samples; N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³)��

After setting up One-dimensional Diffusion Equation, it is determined that the definite condition of this One-dimensional Diffusion Equation.

Wherein, initial condition is:Represent the initial time (namely t=0) concentration value at the gas of the diverse location x of shale samples.

Boundary condition is: and N (0, t)=N₁(t), N (L, t)=N₂(t) (t >=0,0 < x < L); N₁T () represents the concentration value of the not gas of t in the same time in the x=0 position of shale samples, N₂T () represents the concentration value of the not gas of t in the same time in the x=L position of shale samples.

In order to ensure the seriality solved, above-mentioned initial condition and boundary condition must are fulfilled for compatibility condition, it may be assumed that

Afterwards, the data just recorded in gas diffusion process in combinations with pressure transducer, differential pressure pickup and timer, and adopt the separation of variable or calculus of finite differences to solve above-mentioned One-dimensional Diffusion Equation, obtain the diffusion coefficient D of shale samples. Specifically, following steps 302 to step 304:

Step 302, obtains n group force value, and this n group force value is in the process that gas spreads in shale samples, every the force value at the shale samples two ends of predetermined time interval record.

For each group of force value, this group force value includes the pressure value P being placed with the entrance point of the rock core fastener of shale samples_inPressure value P with the port of export_out, n >=2 and n are integer.

Step 303, calculates the n group concentration value of correspondence according to above-mentioned n group force value.

For each group of concentration value, this group concentration value includes the concentration value N of entrance point_inConcentration value N with the port of export_out. Wherein, the concentration value N of entrance point_inCan according to the pressure value P of entrance point_inIt is calculated trying to achieve with upstream gas volume of a container; The concentration value N of the port of export_outCan according to the pressure value P of the port of export_outIt is calculated trying to achieve with gas downstream volume of a container.

Step 304, solves One-dimensional Diffusion Equation according to above-mentioned n group concentration value and obtains the diffusion coefficient D of shale samples.

Diffusion coefficient D is for reflecting gas diffusion in shale samples.

When considering adsorbed gas, One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2\frac{\&PartialD;Q}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;0,0<x<L).$

Above-mentioned One-dimensional Diffusion Equation and definite condition are carried out difference discrete, and the difference scheme obtained is:

$\frac{N_i^{n+1}-N_i^n}{\mathrm{\&Delta;t}}+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2\frac{Q_L^{n+1}-Q_L^n}{\mathrm{\&Delta;t}}-D\frac{N_{i+1}^{n+1}-2N_i^{n+1}+N_{i-1}^{n+1}}{{\mathrm{\&Delta;x}}^2}=0$

$N_0^n=N_1\left(\mathrm{n\&Delta;t}\right),N_I^n=N_2\left(\mathrm{n\&Delta;t}\right)$

NoteThen above-mentioned difference scheme can be changed into:

$-\mathrm{\&alpha;}{N}_{i-1}^{n+1}+(1+2\mathrm{\&alpha;})N_i^{n+1}+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2{Q}_L^{n+1}-\mathrm{\&alpha;}{N}_{i+1}^{n+1}=N_i^n+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2{Q}_L^n$

$N_0^{n+1}=N_1\left(\mathrm{n\&Delta;t}\right),N_I^{n+1}=N_2\left(\mathrm{n\&Delta;t}\right)$

According to record boundary value and initial value (namely above-mentioned n group concentration value) carry out solving calculating, it is possible to obtain the free gas of any time t, optional position x concentration value N (x, t). When the gas in upstream gas container, gas downstream container and shale samples reaches to balance again, namely when concentration value is identical, solves ��, and then solve diffusion coefficient D. Concrete solution procedure can set up Solving Linear, and this is not done concrete introduction by the present embodiment.

When being left out adsorbed gas, One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;\mathrm{0,0}<x<L).$

Same, above-mentioned One-dimensional Diffusion Equation and definite condition are carried out difference discrete, the difference scheme obtained is:

$\frac{N_i^{n+1}-N_i^n}{\mathrm{\&Delta;t}}-D\frac{N_{i+1}^{n+1}-2N_i^{n+1}+N_{i-1}^{n+1}}{{\mathrm{\&Delta;x}}^2}=0$

$N_0^n=N_1\left(\mathrm{n\&Delta;t}\right),N_I^n=N_2\left(\mathrm{n\&Delta;t}\right)$

NoteThen above-mentioned difference scheme can be changed into:

$-\mathrm{\&alpha;}{N}_{i-1}^{n+1}+(1+2\mathrm{\&alpha;})N_i^{n+1}-\mathrm{\&alpha;}{N}_{i+1}^{n+1}=N_i^n$

$N_0^{n+1}=N_1\left(\mathrm{n\&Delta;t}\right),N_I^{n+1}=N_2\left(\mathrm{n\&Delta;t}\right)$

According to record boundary value and initial value (namely above-mentioned n group concentration value) carry out solving calculating, it is possible to obtain the free gas of any time t, optional position x concentration value N (x, t). When the gas in upstream gas container, gas downstream container and shale samples reaches to balance again, namely when concentration value is identical, solves ��, and then solve diffusion coefficient D. Concrete solution procedure can set up Solving Linear, and this is not done concrete introduction by the present embodiment.

Step 305, calculates the permeability k of shale samples:

K=D �� �� ��_t��

The above-mentioned One-dimensional Diffusion Equation about concentration is converted into about after the One-dimensional Diffusion Equation of pressure, it is possible to obtain the relational expression of diffusion coefficient D and permeability k:

$D=\frac{k}{\mathrm{\&mu;\&phi;}{\mathrm{\&beta;}}_t};$

Wherein, D represents diffusion coefficient (m²/ s); �� represents fluid viscosity (Pa s); �� represents the effecive porosity (%) of shale samples; ��_tRepresent the coefficient of compressibility (Pa under initial pore pressure^-1)��

Therefore, permeability k=D �� �� ��_t��

It should be noted is that: in the present embodiment, calculated permeability k is the apparent permeability based on diffusion. In calculating process, owing to considering the impact of adsorbed gas so that result of calculation is relatively less than normal, result of calculation is more accurate.

Optionally, in conjunction with the experimental procedure of the adsorbed gas content with reference to said determination shale samples, the shale character assay method that the present embodiment provides calculates the adsorbed gas content of shale samples also by following steps 306.

Step 306, calculates the adsorbed gas content Q of shale samples_n:

$Q_n=\frac{V_n}{m};$

Wherein, Q_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that the shale samples of unit mass adsorbs³/ kg); M represents the quality (kg) of shale samples; V_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that shale samples adsorbs³);T₀Representing room temperature (DEG C), T represents experimental temperature (DEG C), P₀Represent normal atmosphere (MPa), V_hRepresent the upstream gas volume of a container (m being connected with the entrance point of rock core fastener³), V_��Represent the pore volume (m of rock core fastener³), P_nRepresent the n-th pulsating pressure (MPa), P_n ^*Represent the n-th adsorption equilibrium pressure (MPa), Z_nRepresent that gas is in pressure P_nUnder compressibility factor, Z_n ^*Represent that gas is in pressure P_n ^*Under compressibility factor; As n=1, $V_1=\frac{T_0}{T{P}_0}(\frac{P_1{V}_h}{Z_1}-\frac{P_1^{*}{V}_h}{Z_1^{*}}-\frac{P_1^{*}{V}_{\mathrm{\&phi;}}}{Z_1^{*}}).$

Further, Lan Shi (Langmuir) equation is utilized:The adsorbed gas content under any pressure can be obtained. Wherein, v represents gas adsorbance (cm under balance pressure p³/ g); v_mRepresent single molecular layer saturated absorption (cm³/ g); P represents gas pressure (MPa); B represents the constant relevant with temperature and adsorbent; v_LFor Langmuir volume, representing maximum adsorption ability, its physical significance is: at a given temperature, adsorbed gas content (cm when shale adsorbed methane reaches capacity³/ g); p_LFor Langmuir pressure, the pressure corresponding to the half of Langmuir volume, its value is equivalent to 1/b (MPa).

It addition, in desorption process, the 1st desorbing balance pressure p '_J(1) the stripping gas volume V corresponding to_J(1):

N-th desorbing balance pressure p '_JStripping gas volume V corresponding to (n)_J(n):

Can obtain, balance under pressure in the n-th desorbing, the desorption quantity Q of shale samples_J(n):

$Q_J\left(n\right)=\frac{V_J\left(n\right)}{m};$

Desorption rate v (n):

$v\left(n\right)=\frac{V_J\left(n\right)}{t\left(n\right)};$

Wherein, V_J(1) the 1st desorbing balance pressure P is represented_JStripping gas volume (m corresponding to ' (1)³); V_JN () represents the n-th desorbing balance pressure p_JStripping gas volume (m corresponding to ' (n)³); P_J(1) the balance pressure (MPa) before the balance pressure reduced in rock core fastener is represented the 1st time; P_J' (1) represents the 1st desorbing balance pressure (MPa); P_JN () represents the balance pressure (MPa) before the balance pressure that n-th reduces in rock core fastener; p_J' (n) represents the n-th desorbing balance pressure (MPa); Z_J(1) represent that gas is in pressure P_J(1) compressibility factor under; Z_J' (1) represents that gas is in pressure P_JCompressibility factor under ' (1); Z_JN () represents that gas is in pressure P_JCompressibility factor under (n); Z_J' (n) represents that gas is in pressure p_JCompressibility factor under ' (n); M represents the quality (kg) of shale samples; T) n (represents the time (s) spent by n-th desorption process.

In sum, the shale character assay method that the present embodiment provides, obtain the diffusion coefficient of shale samples by solving the One-dimensional Diffusion Equation pre-build, and then try to achieve the permeability of shale samples according to diffusion coefficient; Solve the assay method that background technology relates to and do not consider the Non-Darcy's flow dynamic characteristic of shale gas and the impact of adsorbed gas when measuring the permeability of shale, the inaccurate problem of measurement result caused; When solving the permeability of shale samples, both consider Non-Darcy's flow dynamic characteristic, it is contemplated that the impact of adsorbed gas, substantially increase the accuracy of measurement result.

It addition, the shale character assay method that the present embodiment provides, additionally provide the computational methods of the related physical quantities such as the porosity of shale samples, free gas content, adsorbed gas content, it is achieved that the synthesis measuring effect of comprehensive, multi-angle.

In the another embodiment provided on the basis based on above-mentioned Fig. 2 and Fig. 3 A illustrated embodiment, also can measure shale slip flows and occurrence condition by the analyzer of shale character shown in Fig. 1. Concrete, it is possible to include following several experimental procedure:

(1) diameter d, length L and the quality m of shale samples are measured;

(2) experimental procedure adopting above-mentioned introduction measures shale samples porosity �� under formation conditions and permeability k;

(3) to a minimum pressure pulse so that the pressure in upstream gas container 101, gas downstream container 105 and rock core fastener 103 reaches balance;

(4) to several pressure pulses of upstream gas container 101, until experiment maximum pressure; In the process, the permeability k of shale samples is measured respectively_i, when pressure in upstream gas container 101, gas downstream container 105 and rock core fastener 103 reaches to balance, measure balance pressure p_i, and this balance pressure is designated as average pressure; Wherein, permeability k_iCorresponding to average pressure p_i;

(5) different average pressure p is adopted_iUnder permeability k_iThe ratio of value and permeability k evaluates shale slip flows ability.

In above-mentioned experiment, it is necessary to note following some:

1, after structure according to Fig. 1 connects each instrument, it is necessary to the air-tightness of checking experiment device;

2, before the experiments, need to by whole experimental provision evacuation, it is ensured that in each instrument, there is no inclusion of air, reduce experimental error;

3, experimental temperature controls formation temperature about 90 DEG C;

4, the confined pressure simulated formation degree of depth is the pressure at about 2000m place, is approximately 50MPa; Wherein, confined pressure p=Zg ��, Z represent that shale reservoir buried depth (m), g represent acceleration of gravity (N/kg), and �� represents shale samples density (g/cm³);

5, the maximum average pore pressure of experimental design is original formation pressure, namely 50MPa;

6, pressure pulse can be respectively set to 2MPa, 3MPa, 5MPa, 6MPa and 8MPa; After pressure pulse reaches 8MPa, carry out permeability determination with constant 8MPa pressure pulse, until average pore pressure reaches the maximum average pore pressure of experimental design.

In the another embodiment provided on the basis based on above-mentioned Fig. 2 and Fig. 3 A illustrated embodiment, also can be measured shale permeability under different confined pressures and porosity namely stress sensitivity by the analyzer of shale character shown in Fig. 1. Specific experiment step can refer to the experimental procedure of said determination permeability and porosity, it is only necessary to adjusts confined pressure in experimentation.

Following for apparatus of the present invention embodiment, it is possible to be used for performing the inventive method embodiment. For the details not disclosed in apparatus of the present invention embodiment, refer to the inventive method embodiment.

Refer to Fig. 4, it illustrates the block diagram of shale character determinator that one embodiment of the invention provides, this shale character determinator can pass through software, hardware or both be implemented in combination with become the some or all of of computing equipment in the analyzer of shale character shown in Fig. 1. This shale character determinator may include that pressure acquisition module 410, concentration calculation module 420, diffusion coefficient computing module 430 and computing permeability module 440.

Pressure acquisition module 410, for obtaining n group force value, described n group force value is in the process that gas spreads in shale samples, force value every the described shale samples two ends of predetermined time interval record, for each group of force value, described force value includes the pressure value P being placed with the entrance point of the rock core fastener of described shale samples_inPressure value P with the port of export_out, n >=2 and n are integer.

Concentration calculation module 420, for calculating the n group concentration value of correspondence according to described n group force value, for each group of concentration value, described concentration value includes the concentration value N of described entrance point_inConcentration value N with the described port of export_out��

Diffusion coefficient computing module 430, obtains the diffusion coefficient D of described shale samples for solving One-dimensional Diffusion Equation according to described n group concentration value, and described diffusion coefficient D is for reflecting gas diffusion in described shale samples.

Computing permeability module 440, for using following formula to calculate the permeability k of described shale samples:

K=D �� �� ��_t;

Wherein, described D represents described diffusion coefficient (m²/ s); Described �� represents fluid viscosity (Pa s); Described �� represents the effecive porosity (%) of described shale samples; Described ��_tRepresent the coefficient of compressibility (Pa under initial pore pressure^-1)��

In sum, the shale character determinator that the present embodiment provides, obtain the diffusion coefficient of shale samples by solving the One-dimensional Diffusion Equation pre-build, and then try to achieve the permeability of shale samples according to diffusion coefficient; Solve the assay method that background technology relates to and do not consider the Non-Darcy's flow dynamic characteristic of shale gas and the impact of adsorbed gas when measuring the permeability of shale, the inaccurate problem of measurement result caused; Substantially increase the accuracy of measurement result.

Refer to Fig. 5, it illustrates the block diagram of shale character determinator that another embodiment of the present invention provides, this shale character determinator can pass through software, hardware or both be implemented in combination with become the some or all of of computing equipment in the analyzer of shale character shown in Fig. 1. This shale character determinator may include that pressure acquisition module 410, concentration calculation module 420, diffusion coefficient computing module 430 and computing permeability module 440.

Pressure acquisition module 410, for obtaining n group force value, described n group force value is in the process that gas spreads in shale samples, force value every the described shale samples two ends of predetermined time interval record, for each group of force value, described force value includes the pressure value P being placed with the entrance point of the rock core fastener of described shale samples_inPressure value P with the port of export_out, n >=2 and n are integer.

Concentration calculation module 420, for calculating the n group concentration value of correspondence according to described n group force value, for each group of concentration value, described concentration value includes the concentration value N of described entrance point_inConcentration value N with the described port of export_out��

Diffusion coefficient computing module 430, obtains the diffusion coefficient D of described shale samples for solving One-dimensional Diffusion Equation according to described n group concentration value, and described diffusion coefficient D is for reflecting gas diffusion in described shale samples.

Wherein, described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;\mathrm{0,0}<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³)��

Or, described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2\frac{\&PartialD;Q}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{\&PartialD;x^2}(t\&GreaterEqual;0,0<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);The increase amount of expression adsorbed gas content corresponding to moment t; Described ��₁Represent the density (kg/m of described shale samples³); Described ��₂Represent gas density (kg/m³)��

Computing permeability module 440, for using following formula to calculate the permeability k of described shale samples:

K=D �� �� ��_t;

Wherein, described D represents described diffusion coefficient (m²/ s); Described �� represents fluid viscosity (Pa s); Described �� represents the effecive porosity (%) of described shale samples; Described ��_tRepresent the coefficient of compressibility (Pa under initial pore pressure^-1)��

Optionally, described device also includes: porosity calculation module 402.

Porosity calculation module 402, for using following formula to calculate the effecive porosity �� of described shale samples:

$\mathrm{\&phi;}=\frac{\frac{Z_2{P}_1{V}_1}{Z_1{P}_2}-V_1-V_x}{\mathrm{SL}};$

Wherein, described S represents the sectional area (m of described shale samples²); Described L represents the length (m) of described shale samples; Described P₁Represent pulsating pressure (MPa); Described P₂Represent balance pressure (MPa); Described Z₁Represent that gas is in pressure P₁Under compressibility factor; Described Z₂Represent that gas is in pressure P₂Under compressibility factor; Described V₁Represent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³); Described V_xRepresent the volume (m of pipeline between described upstream gas container, described upstream inlet valve, described rock core fastener and described downstream inlet valve³)��

Optionally, described device also includes: adsorbed gas computing module 442.

Adsorbed gas computing module 442, for using following formula to calculate the adsorbed gas content Q of described shale samples_n:

$Q_n=\frac{V_n}{m};$

Wherein, described Q_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that the described shale samples of unit mass adsorbs³/ kg); Described m represents the quality (kg) of described shale samples; Described V_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that described shale samples adsorbs³);Described T₀Representing room temperature (DEG C), described T represents experimental temperature (DEG C), described P₀Represent normal atmosphere (MPa), described V_hRepresent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³), described V_��Represent the pore volume (m of described rock core fastener³), described P_nRepresent the n-th pulsating pressure (MPa), described P_n ^*Represent the n-th adsorption equilibrium pressure (MPa), described Z_nRepresent that gas is in pressure P_nUnder compressibility factor, described Z_n ^*Represent that gas is in pressure P_n ^*Under compressibility factor; As n=1, $V_1=\frac{T_0}{T{P}_0}(\frac{P_1{V}_h}{Z_1}-\frac{P_1^{*}{V}_h}{Z_1^{*}}-\frac{P_1^{*}{V}_{\mathrm{\&phi;}}}{Z_1^{*}}).$

In sum, the shale character determinator that the present embodiment provides, obtain the diffusion coefficient of shale samples by solving the One-dimensional Diffusion Equation pre-build, and then try to achieve the permeability of shale samples according to diffusion coefficient; Solve the assay method that background technology relates to and do not consider the Non-Darcy's flow dynamic characteristic of shale gas and the impact of adsorbed gas when measuring the permeability of shale, the inaccurate problem of measurement result caused; When solving the permeability of shale samples, both consider Non-Darcy's flow dynamic characteristic, it is contemplated that the impact of adsorbed gas, substantially increase the accuracy of measurement result.

It addition, the shale character determinator that the present embodiment provides, additionally provide the computing module of the related physical quantities such as the porosity of shale samples, free gas content, adsorbed gas content, it is achieved that the synthesis measuring effect of comprehensive, multi-angle.

It should be understood that the shale character determinator that above-described embodiment provides is when measuring shale character, only it is illustrated with the division of above-mentioned each functional module, in practical application, as desired above-mentioned functions distribution can be completed by different functional modules, it is divided into different functional modules, to complete all or part of function described above by the internal structure of equipment. It addition, the embodiment of the method for the shale character determinator of above-described embodiment offer and shale character assay method belongs to same design, it implements process and refers to embodiment of the method, repeats no more here.

It should be appreciated that it is used in the present context, unless exceptional case clearly supported in context, singulative " " (" a ", " an ", " the ") is intended to also include plural form. It is to be further understood that "and/or" used herein refer to one or the more than one project listed explicitly arbitrarily and likely combine.

The invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.

One of ordinary skill in the art will appreciate that all or part of step realizing above-described embodiment can be completed by hardware, can also be completed by the hardware that program carrys out instruction relevant, described program can be stored in a kind of computer-readable recording medium, storage medium mentioned above can be read only memory, disk or CD etc.

The foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all within the spirit and principles in the present invention, any amendment of making, equivalent replacement, improvement etc., should be included within protection scope of the present invention.

Claims (9)

1. a shale character assay method, it is characterised in that described method includes:

Obtain n group force value, described n group force value is in the process that gas spreads in shale samples, force value every the described shale samples two ends of predetermined time interval record, for each group of force value, described force value includes the pressure value P being placed with the entrance point of the rock core fastener of described shale samples_inPressure value P with the port of export_out, n >=2 and n are integer;

Calculate the n group concentration value of correspondence according to described n group force value, for each group of concentration value, described concentration value includes the concentration value N of described entrance point_inConcentration value N with the described port of export_out;

Solving One-dimensional Diffusion Equation according to described n group concentration value and obtain the diffusion coefficient D of described shale samples, described diffusion coefficient D is for reflecting gas diffusion in described shale samples;

Following formula is used to calculate the permeability k of described shale samples:

K=D �� �� ��_t;

Wherein, described D represents described diffusion coefficient (m²/ s); Described �� represents fluid viscosity (Pa s); Described �� represents the effecive porosity (%) of described shale samples; Described ��_tRepresent the coefficient of compressibility (Pa under initial pore pressure^-1)��

2. method according to claim 1, it is characterised in that

Described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{{\&PartialD;x}^2}(t\&GreaterEqual;\mathrm{0,0}<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);

Or,

Described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2\frac{\&PartialD;Q}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{{\&PartialD;x}^2}(t\&GreaterEqual;\mathrm{0,0}<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);The increase amount of expression adsorbed gas content corresponding to moment t; Described ��₁Represent the density (kg/m of described shale samples³); Described ��₂Represent gas density (kg/m³)��

3. method according to claim 1, it is characterised in that the following formula of described use also includes before calculating the permeability k of described shale samples:

Following formula is used to calculate the effecive porosity �� of described shale samples:

$\mathrm{\&phi;}=\frac{\frac{Z_2{P}_1{V}_1}{Z_1{P}_2}-V_1-V_x}{\mathrm{SL}};$

Wherein, described S represents the sectional area (m of described shale samples²); Described L represents the length (m) of described shale samples; Described P₁Represent pulsating pressure (MPa); Described P₂Represent balance pressure (MPa); Described Z₁Represent that gas is in pressure P₁Under compressibility factor; Described Z₂Represent that gas is in pressure P₂Under compressibility factor; Described V₁Represent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³); Described V_xRepresent the volume (m of pipeline between described upstream gas container, described upstream inlet valve, described rock core fastener and described downstream inlet valve³)��

4. according to the arbitrary described method of claims 1 to 3, it is characterised in that described method also includes:

Following formula is used to calculate the adsorbed gas content Q of described shale samples_n:

$Q_n=\frac{V_n}{m};$

Wherein, described Q_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that the described shale samples of unit mass adsorbs³/ kg); Described m represents the quality (kg) of described shale samples; Described V_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that described shale samples adsorbs³);Described T₀Representing room temperature (DEG C), described T represents experimental temperature (DEG C), described P₀Represent normal atmosphere (MPa), described V_hRepresent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³), described V_��Represent the pore volume (m of described rock core fastener³), described P_nRepresent the n-th pulsating pressure (MPa), described P_n ^*Represent the n-th adsorption equilibrium pressure (MPa), described Z_nRepresent that gas is in pressure P_nUnder compressibility factor, described Z_n ^*Represent that gas is in pressure P_n ^*Under compressibility factor; As n=1, $V_1=\frac{T_0}{{\mathrm{TP}}_0}(\frac{P_1{V}_h}{Z_1}-\frac{{P_1}^{*}{V}_h}{{Z_1}^{*}}-\frac{{P_1}^{*}{V}_{\mathrm{\&phi;}}}{{Z_1}^{*}}).$

5. a shale character determinator, it is characterised in that described device includes:

Pressure acquisition module, for obtaining n group force value, described n group force value is in the process that gas spreads in shale samples, force value every the described shale samples two ends of predetermined time interval record, for each group of force value, described force value includes the pressure value P being placed with the entrance point of the rock core fastener of described shale samples_inPressure value P with the port of export_out, n >=2 and n are integer;

Concentration calculation module, for calculating the n group concentration value of correspondence according to described n group force value, for each group of concentration value, described concentration value includes the concentration value N of described entrance point_inConcentration value N with the described port of export_out;

Diffusion coefficient computing module, obtains the diffusion coefficient D of described shale samples for solving One-dimensional Diffusion Equation according to described n group concentration value, and described diffusion coefficient D is for reflecting gas diffusion in described shale samples;

Computing permeability module, for using following formula to calculate the permeability k of described shale samples:

K=D �� �� ��_t;

Wherein, described D represents described diffusion coefficient (m²/ s); Described �� represents fluid viscosity (Pa s); Described �� represents the effecive porosity (%) of described shale samples; Described ��_tRepresent the coefficient of compressibility (Pa under initial pore pressure^-1)��

6. device according to claim 5, it is characterised in that

Described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{{\&PartialD;x}^2}(t\&GreaterEqual;\mathrm{0,0}<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);

Or,

Described One-dimensional Diffusion Equation is:

$\frac{\&PartialD;N}{\&PartialD;t}+{\mathrm{\&rho;}}_1{\mathrm{\&rho;}}_2\frac{\&PartialD;Q}{\&PartialD;t}=D\frac{{\&PartialD;}^{2}N}{{\&PartialD;x}^2}(t\&GreaterEqual;\mathrm{0,0}<x<L);$

Wherein, described L represents the length (m) of described shale samples; Described N represents that gas is at the concentration value (kg/m corresponding to position x and moment t³);The increase amount of expression adsorbed gas content corresponding to moment t; Described ��₁Represent the density (kg/m of described shale samples³); Described ��₂Represent gas density (kg/m³)��

7. device according to claim 5, it is characterised in that described device also includes:

Porosity calculation module, for using following formula to calculate the effecive porosity �� of described shale samples:

$\mathrm{\&phi;}=\frac{\frac{Z_2{P}_1{V}_1}{Z_1{P}_2}-V_1-V_x}{\mathrm{SL}};$

Wherein, described S represents the sectional area (m of described shale samples²); Described L represents the length (m) of described shale samples; Described P₁Represent pulsating pressure (MPa); Described P₂Represent balance pressure (MPa); Described Z₁Represent that gas is in pressure P₁Under compressibility factor; Described Z₂Represent that gas is in pressure P₂Under compressibility factor; Described V₁Represent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³); Described V_xRepresent the volume (m of pipeline between described upstream gas container, described upstream inlet valve, described rock core fastener and described downstream inlet valve³)��

8. according to the arbitrary described device of claim 5 to 7, it is characterised in that described device also includes:

Adsorbed gas computing module, for using following formula to calculate the adsorbed gas content Q of described shale samples_n:

$Q_n=\frac{V_n}{m};$

Wherein, described Q_nRepresent in the n-th adsorption equilibrium pressure P_n ^*Under, the gas volume (m that the described shale samples of unit mass adsorbs³/ kg); Described m represents the quality (kg) of described shale samples; Described V_nRepresent in the n-th adsorption equilibrium pressure P_n* under, the gas volume (m that described shale samples adsorbs³);Described T₀Representing room temperature (DEG C), described T represents experimental temperature (DEG C), described P₀Represent normal atmosphere (MPa), described V_hRepresent the upstream gas volume of a container (m being connected with the entrance point of described rock core fastener³), described V_��Represent the pore volume (m of described rock core fastener³), described P_nRepresent the n-th pulsating pressure (MPa), described P_n ^*Represent the n-th adsorption equilibrium pressure (MPa), described Z_nRepresent that gas is in pressure P_nUnder compressibility factor, described Z_n ^*Represent that gas is in pressure P_n ^*Under compressibility factor; As n=1, $V_1=\frac{T_0}{{\mathrm{TP}}_0}(\frac{P_1{V}_h}{Z_1}-\frac{{P_1}^{*}{V}_h}{{Z_1}^{*}}-\frac{{P_1}^{*}{V}_{\mathrm{\&phi;}}}{{Z_1}^{*}}).$

9. a shale character analyzer, it is characterized in that, described shale character analyzer includes: upstream gas container, upstream inlet valve, for placing the rock core fastener of shale samples, downstream inlet valve, gas downstream container, upstream hydraulic pump, confined pressure hydraulic pump, downstream hydraulic pump, pressure transducer, differential pressure pickup, confined pressure intake valve, atmospheric valve, calorstat, timer and computing equipment;

Wherein, the entrance point of described rock core fastener passes sequentially through the first valve of described upstream inlet valve, the second valve of described upstream inlet valve is connected with the first end of described upstream gas container; The port of export of described rock core fastener passes sequentially through the first valve of described downstream inlet valve, the second valve of described downstream inlet valve is connected with the first end of described gas downstream container; Described rock core fastener, described upstream gas container and described gas downstream container are installed in described calorstat; Described upstream hydraulic pump is connected with the 3rd valve of described upstream inlet valve by the first pipeline, and described downstream hydraulic pump is connected with the 3rd valve of described downstream inlet valve by the second pipeline; 4th valve of described upstream inlet valve is connected with the 4th valve of described downstream inlet valve by the 3rd pipeline; 5th valve of described upstream inlet valve is connected through the 5th valve of described differential pressure pickup with described downstream inlet valve; Described confined pressure hydraulic pump is connected with the sidewall of described rock core fastener through described confined pressure intake valve; Second end of described upstream gas container is connected with described pressure transducer, and the second end of described gas downstream container is connected with described atmospheric valve; Described pressure transducer, described differential pressure pickup are connected with described computing equipment respectively with described timer;

Described computing equipment, including the shale character determinator as described in as arbitrary in claim 5 to 8.