CN102735592A - Apparatus for measuring diffusion coefficient of carbon dioxide in rock - Google Patents

Abstract

The invention relates to an apparatus used for measuring the diffusion coefficient of carbon dioxide in rock. The apparatus comprises an apparatus housing. A gas tank, a diffusion cylinder and a fluid tank are arranged vertically in parallel in the apparatus housing. A gas pipeline and a liquid pipeline are arranged outside the apparatus housing. The inlet of the gas pipeline is connected to a carbon dioxide cylinder through a booster pump. A four-way valve is arranged in series on the gas pipeline. The gas outlets of the four-way valve are respectively connected to the four-way valve, the gas tank, and a pressure sensor. The inlet of the liquid pipeline is connected with a sample tank. A four-way valve is arranged in series on the liquid pipeline. The liquid outlets of the four-way valve are respectively connected to the four-way valve, the fluid tank, and a pressure sensor. According to the invention, a gas chamber is eliminated fundamentally, and the influence caused by sampling upon the gas pressure is eliminated. Vacuum pumping, saturated formation fluid and the determination of gas diffusion coefficient are integrated. Therefore, the influences on the saturated fluid in rock during the vacuum pumping process are completely eliminated.

Description

A kind of device of measuring carbon dioxide coefficient of diffusion in rock

Technical field

The present invention relates to a kind of device of measuring carbon dioxide coefficient of diffusion in rock, belong to the technical field of petrochemical complex.

Background technology

Carbon dioxide is as main greenhouse gases, and its reduction of discharging problem has been the hot issue of the world today.Scientists study shows, realizes that the effective ways of carbon dioxide discharge-reduction are that geology is buried, yet carrying out carbon dioxide geological when burying, and the selection that its geology is buried the place seems particularly important.This is because execute-in-place mechanism, environment regulator and the public hope to bury security carrying out guaranteeing it when carbon dioxide geological is buried, and guarantees that carbon dioxide can not surmount predetermined border underground, can not leak in the atmosphere once more.Therefore, it is buried the place before burying and carry out safety evaluation and seem particularly important carrying out carbon dioxide geological.

Carbon dioxide constantly is in dynamic disperse state, until reaching balance when ground storage.To bury the place security and need measure the coefficient of diffusion of carbon dioxide in rock in order to assess.The device of at present common mensuration gas coefficient of diffusion in rock, its principle are mostly based on the variation of measuring gas concentration at the rock sample two ends and then calculate the coefficient of diffusion of gas in rock.These class methods need be through carrying out real time sample to rock two ends air chamber; Then each time point gaseous sample is carried out gas chromatographic analysis; Thereby calculate the variation of rock two ends gas concentration, will bring influence to rock two ends air chamber pressure in the moment of taking a sample like this, thereby influence measuring accuracy.And because two air chambers need be set at the rock two ends, cause needs mensuration gas in the rock of saturated resident fluid, during coefficient of diffusion, saturated resident fluid is lost in vacuum, influenced the homogeneity of experiment and stratum full-scale condition.

Summary of the invention

Summary of the invention

To above technical deficiency, the present invention discloses a kind of device of measuring carbon dioxide coefficient of diffusion in rock.The present invention no longer measures carbon dioxide coefficient of diffusion in rock through measuring concentration of carbon dioxide; But obtain carbon dioxide coefficient of diffusion in rock through the variation of measuring carbon dioxide gas pressure: the carbon dioxide state equation through proofreading and correct converses the variation of its concentration, and then determines the coefficient of diffusion of carbon dioxide in rock.The present invention has fundamentally cancelled air chamber, has eliminated the influence that sampling causes gaseous tension, and will vacuumize, the mensuration of saturated resident fluid and gas diffusivity is integrated, thereby thoroughly eliminated in the vacuum influence to saturated fluid in the rock.

Terminological interpretation:

Saturated fluid treatment: be meant through vacuumizing with the whole sucking-offs of air in the tiny hole of filling sample rock interior in the diffusion barrel; Utilize constant-flux pump that the Experimental Flowing Object displacement is gone in the diffusion barrel then; Continuation injection experiments fluid can produce one and build the pressure; Logical when pressure is suppressed 10MPa, make that the Experimental Flowing Object in the diffusion barrel under high pressure is pressed in the hole of filling sample rock, realized all saturated upward Experimental Flowing Objects in the hole of filling sample rock.

Detailed Description Of The Invention

Technical scheme of the present invention is following:

A kind of device of measuring carbon dioxide coefficient of diffusion in rock, it comprises crust of the device 4, tile vertically is provided with gas tank 5, diffusion barrel 6 and fluid tank 9 in said crust of the device 4; In crust of the device 4 outer setting gas pipeline and fluid pipeline are arranged; The inlet of said gas pipeline links to each other with dioxide bottle 3 through supercharge pump 32; Series connection is provided with four-way valve 30 on said gas pipeline, and the gas outlet of said four-way valve 30 links to each other with four-way valve 25, gas tank 5 and pressure transducer 28 respectively; The inlet of said fluid pipeline with join appearance jars 15 and link to each other, on said fluid pipeline, connecting is provided with four-way valve 19, the liquid outlet of said four-way valve 19 links to each other with four-way valve 25, fluid tank 9 and pressure transducer 18 respectively; Said gas tank 5 is used for the carbon dioxide under splendid attire experimental pressure and the temperature; Said fluid tank is used for formation pore fluid or the simulated formation fluid under splendid attire experimental pressure and the temperature;

Be respectively arranged with temperature sensor on the top of gas tank 5, the top of diffusion barrel 6 and the top of fluid tank 9; The bottom of said gas tank 5 links to each other with constant-flux pump 1 through needle-valve 2; The bottom of said diffusion barrel 6 links to each other with check valve 13 through needle-valve 12, and the bottom of said fluid tank 9 links to each other with constant-flux pump 11 through needle-valve 10;

Said four-way valve 25 links to each other with pressure transducer 22 through T-valve 23, and said T-valve 23 links to each other with molecular pump 27 through needle-valve 24;

Axially be provided with piston in the described gas tank 5; Axially be provided with piston in the fluid tank 9; In described gas tank 5, fluid tank 9 and diffusion barrel 6, be provided with well heater.Described well heater is that gas tank 5, fluid tank 9 and diffusion barrel 6 provide heating and heat insulation function.

Preferred according to the present invention; Device at described measurement carbon dioxide coefficient of diffusion in rock also comprises computing machine, described constant-flux pump, needle-valve, check valve 13, joins appearance jars 15, temperature sensor, pressure transducer, four-way valve, T-valve, molecular pump 27, supercharge pump 32 and links to each other with computing machine respectively with well heater.By the running parameter of the above-mentioned parts of computer acquisition, control the operate as normal of above-mentioned parts simultaneously.

Preferred according to the present invention; Said crust of the device is provided with control panel, comprises gas tank pressure display unit, fluid tank pressure display unit, diffusion barrel pressure display unit, temperature control panel, total power switch, heating source switch and computer operated switch on the control panel; Said temperature control panel is used to be provided with the heating-up temperature of well heater; Pressure display unit links to each other with each pressure transducer; Show that dynamically the pressure in each tank body changes in the experimentation; Computer operated switch is used to control and being connected of computer data acquiring, and when computer operated switch was in open mode, computing machine can be gathered each pressure transducer and temperature sensor data in real time.Operating personnel can set basic experiment parameter intuitively through described control panel, and read relevant temperature and pressure numerical value.Pressure transducer among the present invention is used for monitoring in real time each tank body internal pressure, and is transferred to control panel and computing machine; Said temperature sensor is used for monitoring in real time temperature in each tank body, and is transferred to control panel and computing machine; Said T-valve, four-way valve, needle-valve, check valve are used for connecting line and pilot piping switch.

Preferred according to the present invention, be provided with a pair of fixedly snap ring at said diffusion barrel inner top and bottom.Described diffusion barrel is used to load rock sample, and set fixedly snap ring is used for fixing rock sample.

Preferred based on the present invention, in described joining in the appearance jar agitator is installed.Describedly join that appearance jar is used for formation pore fluid that the splendid attire scene provides or according to actual formation pore fluid configuration simulation fluid.

The present invention adopts 3 kinds of power supply devices; Be respectively constant-flux pump, supercharge pump and molecular pump, constant-flux pump 1 links to each other with dioxide bottle, is used for the carbon dioxide displacement of gas tank 5 is gone in the diffusion barrel 6; Constant-flux pump 14 with join appearance jars 15 and link to each other; Be used for the Experimental Flowing Object displacement of fluid tank 9 is gone in the diffusion barrel 6, supercharge pump 32 is connected to after the dioxide bottle 3, is used for dioxide bottle 3 carbon dioxides are delivered in the gas tank 5; Be pressurized to requirement of experiment pressure, molecular pump 27 is used for diffusion barrel 6 and the inner rock sample that loads are vacuumized.

The method of work of a kind of above-mentioned measurement carbon dioxide device of coefficient of diffusion in rock comprises that step is following:

(1) utilize well heater respectively with gas tank 5, fluid tank 9 and diffusion barrel 6 oven dry;

(2) utilize constant-flux pump 1 and constant-flux pump 11 respectively that the piston upper space emptying of gas tank 5 and fluid tank 9 is for use;

(3) will take a sample cylinder rock core or artificial cylinder rock core as filling sample rock; With described filling sample rock oven dry; To load the sample rock with fluid sealant and pack into after the both ends of the surface sealing up and down in the diffusion barrel 6, utilize in the diffusion barrel 6 up and down fixedly snap ring 8 will load the vertical fixed placement of sample rock;

(4) impermeability of the whole device of check;

(5) through supercharge pump 32 carbon dioxide in the dioxide bottle 3 is delivered in the gas tank 5, is pressurized to and wants simulated formation pressure, for use;

(6) Experimental Flowing Object is packed into join in the appearance jars 15, for use; Described Experimental Flowing Object is formation pore fluid or simulated formation fluid, said simulated formation fluid through the configuration in joining appearance jars 15 of previous exploration gained formation pore fluid data obtain, the simulation fluid identical with formation pore fluid character;

(7) Experimental Flowing Object that utilizes constant-flux pump 14 will join in the appearance jar 15 pumps in the fluid tank 9, and utilizes constant-flux pump 11 that the Experimental Flowing Object in the fluid tank 9 is forced into and want simulated formation pressure;

(8) utilize molecular pump 27 that diffusion barrel 6 is vacuumized;

(9) utilize well heater respectively gas tank 5, fluid tank 9, diffusion barrel 6 to be heated, constant temperature is to wanting simulated formation pressure, and is for use;

(10) utilize constant-flux pump 11 that Experimental Flowing Object in the fluid tank 9 is pumped in the diffusion barrel 6, utilize then constant-flux pump 11 with exert pressure in the diffusion barrel 6 to 10MPa, carry out saturated fluid treatment to loading rock sample;

(11) continue to utilize constant-flux pump 11 to carry out pressurized operation, be forced into and want simulated formation pressure through 9 pairs of diffusion barrels of fluid tank, 6 inner Experimental Flowing Objects;

(12) set pressure of adjustment check valve 13, described set pressure is than the little 0.1MPa of diffusion barrel internal pressure;

(13) utilize constant-flux pump 1 that carbon dioxide in the gas tank 5 is pumped in the diffusion barrel 6, since the effect of check valve 13, the Experimental Flowing Object in the emptying diffusion barrel 6;

(14) close needle- valve 12,20,26, utilize pressure transducer 22 to gather original pressure P0, utilize pressure transducer 22 to gather the pressure P 1-Pn of n time point t1～tn, (n is more than or equal to 2);

(15) Δ P be n time point pressure P 1-Pn respectively with the pressure differential of original pressure P0, as, Δ P 1=P1-P0, Δ P 2=P2-P0, Δ P n=Pn-P0; With the pressure drop Δ P 1 ~ Δ P n that calculates with respectively with the corresponding mapping of time point t1～tn; Obtain the curve map of Δ P, calculate the slope k of said curve map cathetus section part with

;

(16) bring the k in the step (15) into formula 1.,

$\mathrm{\&Delta;P}=\frac{4M_{\&infin;}\mathrm{ZRT}\sqrt{D_{\mathrm{eff}}}}{r_{0}V\sqrt{\mathrm{\&pi;}}}\sqrt{t}=\mathrm{<figure-callout\; id="1"\; label="k\; t"\; filenames="HDA00001832447200022.png"\; state="\{\{state\}\}">k</figure-callout>}\sqrt{t}\sqrt{}$ ①

Formula 1. in, Δ P be n time point pressure P 1-Pn respectively with the pressure differential of original pressure P0, as, Δ P 1=P1-P0, Δ P 2=P2-P0, Δ P n=Pn-P0; M _∞Level off to that carbon dioxide diffuses into the amount in the filling sample rock, mol when infinite-the time; Z-compressibility factor is confirmed by the pressure and temperature of experiment; R-universal gas constant, 8.314Pam ³K ^-1Mol ^-1T-experimental temperature, K; D _Eff-carbon dioxide diffusion coefficient; r ₀The xsect radius of-filling sample rock, m; Annular volume between V-rock sample and the diffusion barrel, m ³T-time point comprises t1～tn; K-Δ P and t ^1/2The slope of the straight-line segment that forms part;

1. get by formula,

Can obtain the diffusion coefficient D of carbon dioxide in filling sample rock _Eff

The present invention converses the variation of its concentration through the carbon dioxide state equation of proofreading and correct, and then determines the coefficient of diffusion of carbon dioxide in rock, and said formula derivation 1. is following:

Can know by Fick first diffusion law; When coefficient of diffusion is constant; The diffusion differential equation passive in the rectangular coordinate system, the remittance item is:

(i), wherein C is a gas concentration, D is the coefficient of diffusion of gas; T is the time, and x, y, z are the rectangular coordinate system coordinate;

Through through the expression-form that mathematical coordinate transform obtains under the cylindrical coordinate being with (i) formula:

$\frac{\&PartialD;C}{\&PartialD;t}=\frac{1}{r}\{\frac{\&PartialD;}{\&PartialD;r}\left(\mathrm{rD}\frac{\&PartialD;C}{\&PartialD;r}\right)+\frac{\&PartialD;}{\&PartialD;\mathrm{\&theta;}}\left(\frac{D}{r}\frac{\&PartialD;C}{\&PartialD;\mathrm{\&theta;}}\right)+\frac{\&PartialD;}{\&PartialD;z}\left(\mathrm{rD}\frac{\&PartialD;C}{\&PartialD;z}\right)\}$ （ii）；

Because the used rock core of experiment is the column type rock core; Two butt-end packings up and down; Therefore gas can only get into rock core in radial diffusion, and (ii) the one dimension radial diffusion differential equation that is reduced under the cylindrical coordinate of formula is: (iii);

Combine equation (iii) to carry out following simultaneous according to boundary condition $\left\{\begin{array}{c}\frac{\&PartialD;C}{\&PartialD;t}=D_{\mathrm{Eff}}(\frac{{\&PartialD;}^{2}C}{\&PartialD;{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HDA00001832447200011.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}+\frac{1}{r}\frac{\&PartialD;C}{\&PartialD;r}),0<r<{\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="HDA00001832447200022.png,HDA00001832447200031.png"\; state="\{\{state\}\}">r</figure-callout>}}_0,t\&GreaterEqual;0\\ C{|}_{t=0}=\mathrm{0,0}<r<r_0\\ C{|}_{r={\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="HDA00001832447200022.png,HDA00001832447200031.png"\; state="\{\{state\}\}">r</figure-callout>}}_0}={\mathrm{<figure-callout\; id="0"\; label="C"\; filenames="HDA00001832447200022.png,HDA00001832447200031.png"\; state="\{\{state\}\}">C</figure-callout>}}_0,t\&GreaterEqual;0\end{array}\right.,$ Find the solution obtain equation (iii) separate for:

(iv), J wherein ₀(r α _n) be the zeroth order Bessel function of the first kind, J ₁( _r0 α _n) be the single order Bessel function of the first kind, α _nBe J ₀(r ₀α _nThe positive root of)=0;

Be illustrated in the amount of substance in the gaseous diffusion entering rock core in the time t with Mt; Use M _∞Express time levels off to that gaseous diffusion gets into the amount of substance in the rock core when infinite.Formula (iv) to the radius r integration, is obtained the relational expression between Mt and the time t:

$\frac{M_r}{M_{\&infin;}}=1-\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{4}{{\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="HDA00001832447200022.png,HDA00001832447200031.png"\; state="\{\{state\}\}">r</figure-callout>}}_0^2{\mathrm{\&alpha;}}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00001832447200011.png"\; state="\{\{state\}\}">n</figure-callout>}}^2}\exp (-D_{\mathrm{eff}}{\mathrm{\&alpha;}}_n^{2}t)$ （v）；

During as

, (v) formula can be reduced to:

(vi)

With real gas state equation Δ PV=Z Δ nRT and M _t=Δ n substitution (obtains vi) $\mathrm{\&Delta;\; P}=\frac{4M_{\&infin;}\mathrm{ZRT}\sqrt{D_{\mathrm{Eff}}}}{r_{0}V\sqrt{\mathrm{\&pi;}}}\sqrt{t}=k\sqrt{t}$ (vii), this formula is 1. formula.

The invention has the advantages that:

The present invention no longer measures carbon dioxide coefficient of diffusion in rock through measuring concentration of carbon dioxide; But obtain carbon dioxide coefficient of diffusion in rock through the variation of measuring carbon dioxide gas pressure: the carbon dioxide state equation through proofreading and correct converses the variation of its concentration, and then determines the coefficient of diffusion of carbon dioxide in rock.The present invention has fundamentally cancelled air chamber, has eliminated the influence that sampling causes gaseous tension, and will vacuumize, the mensuration of saturated resident fluid and gas diffusivity is integrated, thereby thoroughly eliminated in the vacuum influence to saturated fluid in the rock.

Description of drawings

Fig. 1 is the structural representation of device according to the invention;

Fig. 2 is the synoptic diagram of the control panel on the crust of the device according to the invention;

Fig. 3 is for through the corresponding time t1 of the P1 in the his-and-hers watches 1～Pn～tn mapping, i.e. pressure variation diagram in time;

Fig. 4 is for through the arithmetic square root mapping of the pressure differential deltap P 1～Δ P n in the his-and-hers watches 1 to time t1～tn, i.e. the pressure reduction variation diagram of arithmetic square root in time.

In Fig. 1,2,1, constant-flux pump; 2, needle-valve; 3, dioxide bottle; 4, crust of the device; 5, gas tank; 6, diffusion barrel; 7, load rock sample; 8, fixing snap ring; 9, fluid tank; 10, needle-valve; 11, constant-flux pump; 12, needle-valve; 13, check valve; 14, constant-flux pump; 15, join appearance jar, 16, needle-valve; 17, temperature sensor; 18, pressure transducer; 19, four-way valve; 20, needle-valve; 21, temperature sensor; 22, pressure transducer; 23, T-valve; 24, needle-valve; 25, four-way valve; 26, needle-valve; 27, molecular pump; 28, pressure transducer; 29, temperature sensor; 30, four-way valve; 31, needle-valve; 32, supercharge pump.

Embodiment

Based on embodiment and Figure of description the present invention is done detailed explanation below, but be not limited thereto.

Embodiment,

As illustrated in fig. 1 and 2.

A kind of device of measuring carbon dioxide coefficient of diffusion in rock, it comprises crust of the device 4, tile vertically is provided with gas tank 5, diffusion barrel 6 and fluid tank 9 in said crust of the device 4; In crust of the device 4 outer setting gas pipeline and fluid pipeline are arranged; The inlet of said gas pipeline links to each other with dioxide bottle 3 through supercharge pump 32; Series connection is provided with four-way valve 30 on said gas pipeline, and the gas outlet of said four-way valve 30 links to each other with four-way valve 25, gas tank 5 and pressure transducer 28 respectively; The inlet of said fluid pipeline with join appearance jars 15 and link to each other, on said fluid pipeline, connecting is provided with four-way valve 19, the liquid outlet of said four-way valve 19 links to each other with four-way valve 25, fluid tank 9 and pressure transducer 18 respectively;

Be respectively arranged with temperature sensor on the top of gas tank 5, the top of diffusion barrel 6 and the top of fluid tank 9; The bottom of said gas tank 5 links to each other with constant-flux pump 1 through needle-valve 2; The bottom of said diffusion barrel 6 links to each other with check valve 13 through needle-valve 12, and the bottom of said fluid tank 9 links to each other with constant-flux pump 11 through needle-valve 10;

Said four-way valve 25 links to each other with pressure transducer 22 through T-valve 23, and said T-valve 23 links to each other with molecular pump 27 through needle-valve 24;

Axially be provided with piston in the described gas tank 5; Axially be provided with piston in the fluid tank 9;

Device at described measurement carbon dioxide coefficient of diffusion in rock also comprises computing machine, described constant-flux pump, needle-valve, check valve 13, joins appearance jars 15, temperature sensor, pressure transducer, four-way valve, T-valve, molecular pump 27, supercharge pump 32 and links to each other with computing machine respectively with well heater.

Said crust of the device is provided with control panel, comprises gas tank pressure display unit, fluid tank pressure display unit, diffusion barrel pressure display unit, temperature control panel, total power switch, heating source switch and computer operated switch on the control panel; Said temperature control panel is used to be provided with the heating-up temperature of well heater; Pressure display unit links to each other with each pressure transducer; Show that dynamically the pressure in each tank body changes in the experimentation; Computer operated switch is used to control and being connected of computer data acquiring, and when computer operated switch was in open mode, computing machine can be gathered each pressure transducer and temperature sensor data in real time.

Be provided with a pair of fixedly snap ring at said diffusion barrel inner top and bottom.In described joining in the appearance jar stirrer is installed.

A kind of method of work like embodiment 1 said measurement carbon dioxide device of coefficient of diffusion in rock comprises that step is following:

(1) utilize well heater respectively with gas tank 5, fluid tank 9 and diffusion barrel 6 oven dry;

(2) utilize constant-flux pump 1 and constant-flux pump 11 respectively that the piston upper space emptying of gas tank 5 and fluid tank 9 is for use;

(3) will take a sample cylinder rock core or artificial cylinder rock core as filling sample rock; With described filling sample rock oven dry; To load the sample rock with fluid sealant and pack into after the both ends of the surface sealing up and down in the diffusion barrel 6, utilize in the diffusion barrel 6 up and down fixedly snap ring 8 will load the vertical fixed placement of sample rock;

(4) impermeability of the whole device of check;

(5) through supercharge pump 32 carbon dioxide in the dioxide bottle 3 is delivered in the gas tank 5, is pressurized to and wants simulated formation pressure, for use;

(6) Experimental Flowing Object is packed into join in the appearance jars 15, for use; Described Experimental Flowing Object is formation pore fluid or simulated formation fluid, said simulated formation fluid through the configuration in joining appearance jars 15 of previous exploration gained formation pore fluid data obtain, the simulation fluid identical with formation pore fluid character;

(7) Experimental Flowing Object that utilizes constant-flux pump 14 will join in the appearance jar 15 pumps in the fluid tank 9, and utilizes constant-flux pump 11 that the Experimental Flowing Object in the fluid tank 9 is forced into and want simulated formation pressure;

(8) utilize molecular pump 27 that diffusion barrel 6 is vacuumized;

(9) utilize well heater respectively gas tank 5, fluid tank 9, diffusion barrel 6 to be heated, constant temperature is to wanting simulated formation pressure, and is for use;

(10) utilize constant-flux pump 11 that Experimental Flowing Object in the fluid tank 9 is pumped in the diffusion barrel 6, utilize then constant-flux pump 11 with exert pressure in the diffusion barrel 6 to 10MPa, carry out saturated fluid treatment to loading rock sample;

(11) continue to utilize constant-flux pump 11 to carry out pressurized operation, be forced into and want simulated formation pressure through 9 pairs of diffusion barrels of fluid tank, 6 inner Experimental Flowing Objects;

(12) set pressure of adjustment check valve 13, described set pressure is than the little 0.1MPa of diffusion barrel internal pressure;

(13) utilize constant-flux pump 1 that carbon dioxide in the gas tank 5 is pumped in the diffusion barrel 6, since the effect of check valve 13, the Experimental Flowing Object in the emptying diffusion barrel 6;

(14) close needle- valve 12,20,26, utilize pressure transducer 22 to gather original pressure P0, utilize pressure transducer 22 to gather the pressure P 1-Pn of n time point t1～tn, table 1 is filled in in (n is more than or equal to 2),

Table 1: utilize pressure transducer 22 to gather the pressure P 1-Pn of each time point and the pressure reduction that calculates

Through the pressure in the his-and-hers watches 1 time is mapped, obtain pressure variation diagram in time, see Fig. 3;

(15) Δ P be n time point pressure P 1-Pn respectively with the pressure differential of original pressure P0, as, Δ P 1=P1-P0, Δ P 2=P2-P0, Δ P n=Pn-P0; Through the arithmetic square root mapping of the pressure reduction in the his-and-hers watches 1 to the time; Obtain the pressure reduction variation diagram of arithmetic square root in time; See Fig. 4; Obtain the curve map of Δ P, calculate slope k=19.0220 of curve map cathetus section part among said Fig. 4 with

; It is very fast as can be seen from Figure 4 to spread the initial period pressure drop, not linear, and this mainly is because this stage is diffusion unstable state state; When reaching the diffusion lower state, the arithmetic square root of pressure drop and time is linear;

(16) bring the k in the step (15) into formula 1.,

$\mathrm{\&Delta;P}=\frac{4M_{\&infin;}\mathrm{ZRT}\sqrt{D_{\mathrm{eff}}}}{r_{0}V\sqrt{\mathrm{\&pi;}}}\sqrt{t}=\mathrm{<figure-callout\; id="1"\; label="k\; t"\; filenames="HDA00001832447200022.png"\; state="\{\{state\}\}">k</figure-callout>}\sqrt{t}\sqrt{}$ ①

Formula 1. in, Δ P be n time point pressure P 1-Pn respectively with the pressure differential of original pressure P0, as, Δ P 1=P1-P0, Δ P 2=P2-P0, Δ P n=Pn-P0; M _∞Level off to that carbon dioxide diffuses into the amount in the filling sample rock, mol when infinite-the time; Z-compressibility factor is confirmed by the pressure and temperature of experiment; R-universal gas constant, 8.314Pam ³K ^-1Mol ^-1T-experimental temperature, K; D _Eff-carbon dioxide diffusion coefficient; r ₀The xsect radius of-filling sample rock, m; Annular volume between V-rock sample and the diffusion barrel, m ³T-time point comprises t1～tn; K-Δ P and t ^1/2The slope of the straight-line segment that forms part;

1. get by formula,

Can obtain the diffusion coefficient D of carbon dioxide in filling sample rock _Eff=1.65 * 10 ^-10m ²/ s fills in into table 2.

Table 2

Claims (5)

1. a device of measuring carbon dioxide coefficient of diffusion in rock is characterized in that, it comprises crust of the device (4), and tile vertically is provided with gas tank (5), diffusion barrel (6) and fluid tank (9) in said crust of the device (4); In crust of the device (4) outer setting gas pipeline and fluid pipeline are arranged; The inlet of said gas pipeline links to each other with dioxide bottle (3) through supercharge pump (32); Series connection is provided with four-way valve (30) on said gas pipeline, and the gas outlet of said four-way valve (30) links to each other with four-way valve (25), gas tank (5) and pressure transducer (28) respectively; The inlet of said fluid pipeline links to each other with joining kind jar (15), and series connection is provided with four-way valve (19) on said fluid pipeline, and the liquid outlet of said four-way valve (19) links to each other with four-way valve (25), fluid tank (9) and pressure transducer (18) respectively;

Be respectively arranged with temperature sensor on the top of gas tank (5), the top of diffusion barrel (6) and the top of fluid tank (9); The bottom of said gas tank (5) links to each other with constant-flux pump (1) through needle-valve (2); The bottom of said diffusion barrel (6) links to each other with check valve (13) through needle-valve (12), and the bottom of said fluid tank (9) links to each other with constant-flux pump (11) through needle-valve (10); Said four-way valve (25) links to each other with pressure transducer (22) through T-valve (23), and said T-valve (23) links to each other with molecular pump (27) through needle-valve (24); Axially be provided with piston in the described gas tank (5); Axially be provided with piston in the fluid tank (9); In described gas tank (5), fluid tank (9) and diffusion barrel (6), be provided with well heater.

2. a kind of device of measuring carbon dioxide coefficient of diffusion in rock according to claim 1; It is characterized in that; Device at described measurement carbon dioxide coefficient of diffusion in rock also comprises computing machine, described constant-flux pump, needle-valve, check valve (13), join appearance jar (15), a temperature sensor, pressure transducer, four-way valve, T-valve, molecular pump (27), supercharge pump (32) links to each other with computing machine respectively with well heater.

3. a kind of device of measuring carbon dioxide coefficient of diffusion in rock according to claim 2; It is characterized in that; Said crust of the device is provided with control panel, comprises gas tank pressure display unit, fluid tank pressure display unit, diffusion barrel pressure display unit, temperature control panel, total power switch, heating source switch and computer operated switch on the control panel; Said temperature control panel is used to be provided with the heating-up temperature of well heater; Pressure display unit links to each other with each pressure transducer; Show that dynamically the pressure in each tank body changes in the experimentation; Computer operated switch is used to control and being connected of computer data acquiring, when computer operated switch is in open mode, and each pressure transducer of computer real-time acquisition and temperature sensor data.

4. a kind of device of measuring carbon dioxide coefficient of diffusion in rock according to claim 1 is characterized in that, is provided with a pair of fixedly snap ring at said diffusion barrel inner top and bottom.

5. a kind of device of measuring carbon dioxide coefficient of diffusion in rock according to claim 1 is characterized in that, in described joining in the appearance jar stirrer is installed.

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