CN102590045B - Oil-gas interface tension test method in porous medium - Google Patents

Abstract

The invention provides an oil-gas interface tension test method in a porous medium, comprising the following steps: A, performing a displacement experiment in a sample formed by the porous medium to obtain an oil-gas sample; and B, performing the chromatographic analysis on the obtained oil-gas sample to obtain an oil-gas chromatographic component and obtaining the oil-gas interface tension in the porous medium by the oil-gas chromatographic component. The oil-gas interface tension test method has the following advantages: 1, the natural porous medium is used as a test medium to really reflect the oil-gas interface interaction rule under the oil reservation condition; 2, a stratum oil dissolubility calculation formula is derived using the Peng-Robinson equation of state (PR-EOS) in combination with dissolubility theory in the calculation method and applied to the interface force tension calculation; 3, the direct, real interface tension data is provided to design and optimize a schemeof an oil reservation engineering project; and 4, the tension on different cross sections of the natural porous medium is researched to make it possible to research the change in the interface tension field in the natural porous medium from now.

Description

Oil-gas interface tension test method in the porous medium

Technical field

The present invention relates to oil high pressure property experiment field, the oil-gas interface tension test method in a kind of porous medium.

Background technology

Along with the scale of rig-site utilization at home and abroad of gas drive technology of reservoir sweep constantly enlarges, how exactly, truly the oil gas interface tension value that obtains in the oil reservoir becomes the key that the petroleum engineer solves many technology of reservoir sweep problems.At present, the method for testing of oil gas interface tension force is mainly the hanging drop method of testing, and the method is in a visual container, utilizes hanging drop pipe vertically downward to drip a droplet oil droplet, then utilizes the computer generated image technology according to drop profile calculation interface tension value.

This kind method is similar to and tests the phase parameters such as bubble point, dew point in the PVT instrument, the not participation of porous medium, intermolecular acting force between the oil gas interface is different from the intermolecular acting force in the porous medium, can not reflect faithfully that porous medium is on the impact of oil gas interface tension force.Thereby, this value is not the oil gas interface tension value under the actual reservoir condition, also just can not represent veritably the oil gas interface interactively in the stratum, bring certain error for the relevant correction of the analysis of gas drive oil-displacement mechanism, reservoir engineering conceptual design and method for numerical simulation.

Summary of the invention

The present invention aims to provide the oil-gas interface tension test method in a kind of porous medium, with solve existing oil-gas interface tension test method can not reflect faithfully porous medium on the impact of oil gas interface tension force, can not truly measure the problem of the oil gas interface tension value under the actual reservoir condition.

For this reason, the present invention proposes the oil-gas interface tension test method in a kind of porous medium, and the oil-gas interface tension test method in the described porous medium comprises: A, carry out displacement test to obtain the oil gas sample in the sample that porous medium forms; B, the oil gas sample that obtains is carried out stratographic analysis obtaining the oil gas chromatographic component, obtain oil gas interface tension force in the porous medium by the oil gas chromatographic component.

Wherein, the oil gas chromatographic component refers to: displacement gas mole percent level (weight coefficient), utilize following formula calculation interface tension force.

Computation process: 1. utilize formula (1) to carry out Newton iteration solution PR-EOS equation and obtain displacement molar volume of gas v;

2. utilize formula (2), formula (3) to calculate respectively the solubility of oil, gas;

3. utilize formula (4) calculation interface tension force;

$P=\frac{\mathrm{RT}}{v-b}-\frac{a\left(T\right)}{v(v+b)+b(v-b)}$ Formula (1)

${\mathrm{\δ}}_{\mathrm{oll}}={\left[\frac{a\left(T\right)(1+\mathrm{\κ}\·T_r^{0.5})}{v(v+b)+b(v-b)}\left(\frac{1+\mathrm{\κ}-k{T}_r^{0.5}}{{[1+k(1-T_r^{0.5})]}^2}\right)\right]}^{0.5}$ Formula (2)

${\mathrm{\δ}}_{\mathrm{gas}}=1.25{\left(P_C\right)}^{0.5}\frac{{\mathrm{\ρ}}_r}{{\mathrm{\ρ}}_r\left(\mathrm{liq}\right)}$ Formula (3)

σ=δ ²V ^0.33/ A formula (4)

Wherein, P is the displacement gaseous tension, and R is gas law constant, and T is the displacement gas temperature, and v is the displacement gas volume, and b is----equation of gas state coefficient, a (T) are----equation of gas state coefficient, k are----equation of gas state coefficient, δ _OllFor----oily solubility, δ _GasBe----gas (body) solubility, Tr is----reduced temperature, and Pc is----emergent pressure, ρ _rFor----gas reduced density (density under the test condition is divided by critical density), ρ _{R (liq)}For---(this parameter is that experience provides to-liquid reduced density, be constant), δ refers to oil, gas solubility weight sum, V equals gas weight (weight coefficient) and multiply by v, weight coefficient can obtain by the data of oil gas chromatographic component, and A is---the interface constant.

Further, the sample that described porous medium forms is natural core, uses carbon dioxide or nitrogen as displacement gas in the described displacement test.

Further, the length direction of the sample that forms along described porous medium arranges a plurality of sampling spots, with the oil gas sample at the different cross section place that obtains described sample.

Further, oil-gas interface tension test method in the described porous medium uses the oil-gas interface tension test device in the porous medium to test, and the oil-gas interface tension test device in the described porous medium comprises: driving device, the sampler that is connected with driving device and the on-line chromatograph analytical equipment that is connected with sampler.

Further, described driving device comprises: core holding unit, be provided with cavity fixing and the sealing natural core, and described core holding unit has import and the outlet that is connected with cavity; The displacement pipeline, import by core holding unit connects natural core, the displacement pump, the oil that displacement is used and displacement gas are pumped into respectively in the displacement pipeline, oil tank and displacement gas storage tank, have respectively the volume that holds the used oil of displacement and displacement gas, described oil tank and displacement gas storage tank are connected in parallel between displacement pump and the displacement pipeline; Discharge pipe is connected with the outlet of described core holding unit; Check valve is arranged on the described discharge pipe.

Further, institute's sampler is stated and is comprised: stopple coupon, extend in the described core holding unit, and be connected along the length direction setting of vertical natural core and with natural core; Valve and filtrator are connected in series with described stopple coupon.

Further, described on-line chromatograph analytical equipment is the on-line chromatograph analyser, described driving device also comprises: be horizontally set on natural core in the core holding unit, described stopple coupon is a plurality of, one end of described a plurality of stopple coupons is disposed on the different cross section place of natural core along the length direction of natural core, the other end of described a plurality of stopple coupons is in parallel with the on-line chromatograph analyser.

Further, described natural core is bar-shaped, and length is 30cm to 100cm, described stopple coupon is 5, be respectively the first stopple coupon, the second stopple coupon, the 3rd stopple coupon, the 4th stopple coupon and the 5th stopple coupon, each stopple coupon spaced set, each stopple coupon is connected in series with valve and filtrator.

Further, the oil-gas interface tension test method in the porous medium specifically may further comprise the steps,

(1) sets check valve pressure;

(2) make the used oil of displacement enter core holding unit and natural core from the displacement pipeline by the displacement pump, making the displacement pump is pressure constant state, pressure is higher than check valve set pressure 0.5MPa, and makes the oil volume that enters natural core reach 3 times of multiple of active porosity volume; (3) stop to make the used oil of displacement to enter core holding unit from the displacement pipeline, utilize the displacement pump to keep core holding unit pressure to be higher than check valve set pressure 0.5MPa, then carry out carbon dioxide displacement process;

(4) displacement is opened the valve that is connected with the first stopple coupon to the active porosity volume of setting multiple, makes oil gas sample in the first stopple coupon enter the on-line chromatograph analyser and obtains oil gas chromatographic component in the first stopple coupon, then closes the first stopple coupon;

(5) open the valve that is connected with the second stopple coupon, make oil gas sample in the second stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the second stopple coupon, then close the second stopple coupon;

(6) open the valve that is connected with the 3rd stopple coupon, make oil gas sample in the 3rd stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the 3rd stopple coupon, then close the 3rd stopple coupon;

(7) open the valve that is connected with the 4th stopple coupon, make oil gas sample in the 4th stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the 4th stopple coupon, then close the 4th stopple coupon;

(8) open the valve that is connected with the 5th stopple coupon, make oil gas sample in the 5th stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the 5th stopple coupon, then close the 5th stopple coupon.

Compare with existing method, the present invention has the following advantages:

1. take natural porous media as tested media, can reflect truly under the reservoir condition oil gas interface interaction rule;

2. utilize PR-EOS to derive formation oil solubility calculation formula in conjunction with the solubility theory on the computing method, and should be in interfacial tension is calculated;

3. be reservoir engineering conceptual design and optimization, direct, real interfacial tension data are provided;

4. can study the tension force at natural porous media different cross section place, provide a kind of possibility for studying from now on the tension field variation of natural porous media median surface.

5. with respect to traditional hanging drop method of testing, among the present invention, stopple coupon is not limited to vertical setting, if the length direction of vertical porous medium, thereby so that the precision of stopple coupon and other instruments is minimized, be convenient to install and adjust at any time.

Description of drawings

Fig. 1 is the porous medium median surface tension test method flow schematic diagram according to the embodiment of the invention;

Fig. 2 is the interfacial tension when measuring the different cross section position according to the porous medium median surface tension test method of the embodiment of the invention.

The drawing reference numeral explanation:

10, sample 12, the core holding unit entrance of core holding unit 11, porous medium formation

13, fluororubber cylinder 14, core holding unit outlet 15, lower house 20, stopple coupon

21, the first stopple coupon 22, the second stopple coupon 23, the 3rd stopple coupon 24, the 4th stopple coupon

25, the 5th stopple coupon 30, on-line chromatograph analytical equipment 40, check valve 41, fluid reservoir

50, displacement pump 60, displacement pipeline 70, displacement gas storage tank 71, valve

73, valve 80, storage tank 81, valve 83, valve 90, filtrator

91, valve 92, valve 93, valve 94, valve 95, valve

Embodiment

Understand for technical characterictic of the present invention, purpose and effect being had more clearly, now contrast description of drawings the specific embodiment of the present invention.

Fig. 1 is the porous medium median surface tension test method flow schematic diagram according to the embodiment of the invention, as shown in Figure 1, comprise according to the oil-gas interface tension test method in the porous medium of the embodiment of the invention: A, in the sample 11 that porous medium forms, carry out displacement test to obtain the oil gas sample; B, the oil gas sample that obtains is carried out stratographic analysis obtaining the oil gas chromatographic component, obtain oil gas interface tension force in the porous medium by the oil gas chromatographic component.

Wherein, the oil gas chromatographic component refers to: displacement gas mole percent level (weight coefficient), utilize following formula calculation interface tension force.

Computation process: 1. utilize formula (1) to carry out Newton iteration solution PR-EOS equation and obtain molar volume;

2. utilize formula (2), formula (3) to calculate respectively the solubility of oil gas;

3. utilize formula (4) calculation interface tension force;

$P=\frac{\mathrm{RT}}{v-b}-\frac{a\left(T\right)}{v(v+b)+b(v-b)}$ Formula (1)

${\mathrm{\δ}}_{\mathrm{oll}}={\left[\frac{a\left(T\right)(1+\mathrm{\κ}\·T_r^{0.5})}{v(v+b)+b(v-b)}\left(\frac{1+\mathrm{\κ}-k{T}_r^{0.5}}{{[1+k(1-T_r^{0.5})]}^2}\right)\right]}^{0.5}$ Formula (2)

${\mathrm{\δ}}_{\mathrm{gas}}=1.25{\left(P_C\right)}^{0.5}\frac{{\mathrm{\ρ}}_r}{{\mathrm{\ρ}}_r\left(\mathrm{liq}\right)}$ Formula (3)

σ=δ ²V ^0.33/ A formula (4)

Further, as shown in Figure 1, the sample 11 that described porous medium forms is natural core, like this near actual oil reservoir situation, can certainly adopt other porous mediums, for example glass uses carbon dioxide or nitrogen as displacement gas as sample in the described displacement test.

Further, oil-gas interface tension test method in the described porous medium uses the oil-gas interface tension test device in the porous medium to test, and the oil-gas interface tension test device in the described porous medium comprises: driving device, the sampler that is connected with driving device and the on-line chromatograph analytical equipment that is connected with sampler.The present invention utilizes PR-EOS to derive formation oil solubility calculation formula in conjunction with the solubility theory, and should be in interfacial tension is calculated; Be reservoir engineering conceptual design and optimization, direct, real interfacial tension data are provided; Be not both with conventional hanging drop method of testing: the method is directly carried out the interfacial tension measurement in porous medium, can reflect truly under the reservoir condition, and oil gas interface interaction rule, and conventional method can't realize.

Further, described driving device comprises: core holding unit 10, be provided with cavity fixing and the sealing natural core, and described core holding unit has import 12 and the outlet 14 that is connected with cavity; Displacement pipeline 60, import 12 by core holding unit connects natural core, displacement pump 50, the oil that displacement is used and displacement gas are pumped into respectively in the displacement pipeline 60, oil tank 80 and displacement gas storage tank 70, have respectively the volume that holds the used oil of displacement and displacement gas, described oil tank 80 and displacement gas storage tank 70 are connected in parallel between displacement pump 50 and the displacement pipeline 60; Discharge pipe 16 is connected with the outlet 14 of described core holding unit; Check valve 40 is arranged on the described discharge pipe 16.

Core holding unit 10 can be tubular, and fixedly the natural core sample is established fluororubber cylinder 13 in the core holding unit 10, the side direction of fastening natural core.Containing formation oil samples in the oil tank 80, displacement pump 50 for example are ram pump, for displacement process provides power, and check valve 40, control displacement pressure reduction guarantees the reliable and stable of displacement.Displacement pipeline 60 and discharge pipe 16 are connected to the two ends of natural core sample, finish displacement process from the end direction of natural core sample, and displacement oil out can be collected in the fluid reservoir 41 that is connected on the discharge pipe 16.

Further, institute's sampler is stated and is comprised: stopple coupon 20, extend in the described core holding unit 10, be connected along the length direction setting of vertical natural core and with natural core, timing acquisition oil-gas component, stopple coupon can adopt existing suitable structure, be not both with conventional hanging drop method of testing: stopple coupon is not limited to vertical setting, if the length direction of vertical natural core, thereby can arrange flexibly, made things convenient for installation; Valve and filtrator 90 are connected in series with described stopple coupon.The valve that arranges on the stopple coupon is microsample valve, and the sample velocities that control enters the on-line chromatograph analytical equipment reduces the system pressure fluctuation.

Further, described on-line chromatograph analytical equipment is the on-line chromatograph analyser, and analyzing oil and gas forms.Further, as shown in Figure 1, the length direction of the sample that forms along described porous medium arranges a plurality of sampling spots, with the oil gas sample at the different cross section place that obtains described sample.Described driving device also comprises: be horizontally set on natural core in the core holding unit 10, described stopple coupon is a plurality of, one end of described a plurality of stopple coupons is disposed on the different cross section place of natural core along the length direction of natural core, the other end of described a plurality of stopple coupons is in parallel with the on-line chromatograph analyser.Like this, can study the tension force at natural porous media different cross section place, provide a kind of possibility for studying from now on the tension field variation of natural porous media median surface.

Further, as shown in Figure 1, described natural core is bar-shaped, length is 30cm to 100cm, described stopple coupon is 5, be respectively the first stopple coupon 21, the second stopple coupon 22, the 3rd stopple coupon 23, the 4th stopple coupon 24 and the 5th stopple coupon 25, each stopple coupon spaced set, each stopple coupon is connected in series with valve and filtrator.The first stopple coupon 21 is connected in series with valve 91 and filtrator 90, the second stopple coupon 22 is connected in series with valve 92 and filtrator 90, the 3rd stopple coupon 23 is connected in series with valve 93 and filtrator 90, the 4th stopple coupon 24 is connected in series with valve 94 and filtrator 90, the 5th stopple coupon 25 is connected in series with valve 95 and filtrator 90, and wherein, the valve that arranges on each stopple coupon is microsample valve, the sample velocities that control enters on-line chromatograph analytical equipment 30 reduces the system pressure fluctuation.Certainly, natural core length is longer, and sampling spot is more, for example is 8,10, more can reflect the tension force at different cross section place, more is conducive to research.

Further, the oil-gas interface tension test method in the porous medium specifically may further comprise the steps:

(1) setting check valve pressure, is 10MPa for example, closes all valves;

(2) make the used oil of displacement enter core holding unit 10 and natural core from displacement pipeline 60 by displacement pump 50, opening valve 83, valve 81, to make the displacement pump be pressure constant state, pressure is higher than check valve set pressure 0.5MPa, and makes the oil volume that enters natural core reach 3 times (3HCPV) of the multiple of active porosity volume;

(3) valve-off 83, valve 81, stop to make the used oil of displacement to enter core holding unit from the displacement pipeline, utilize the displacement pump to keep core holding unit pressure to be higher than check valve set pressure 0.5MPa, then open valve 73, valve 71 carries out carbon dioxide displacement process;

(4) displacement is to the active porosity volume of setting multiple, for example oil volume is the multiple (1HCPV) of one times active porosity volume, (this value can according to the experiment purpose adjustment) opens the valve 91 that is connected with the first stopple coupon 21, make oil gas sample in the first stopple coupon 21 enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the first stopple coupon 21, then valve-off 91, thereby close the first stopple coupon 21;

(5) open the valve 92 that is connected with the second stopple coupon 22, make oil gas sample in the second stopple coupon 22 enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the second stopple coupon 22, then valve-off 92, thereby close the second stopple coupon 22;

(6) open the valve 93 that is connected with the 3rd stopple coupon 23, make oil gas sample in the 3rd stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the 3rd stopple coupon, then valve-off 93, thereby close the 3rd stopple coupon 23;

(7) open and the 4th sampling 24 valves 94 that are connected of pipe, make oil gas sample in the 4th stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the 4th stopple coupon, then valve-off 94, thereby close the 4th stopple coupon 24;

(8) open the valve 95 that is connected with the 5th stopple coupon 25, make oil gas sample in the 5th stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the 5th stopple coupon, then valve-off 95, thereby close the 5th stopple coupon 25.

(9) utilize following formula calculation interface tension force.

Computation process: 1. utilize formula (1) to carry out Newton iteration solution PR-EOS equation and obtain molar volume;

2. utilize formula (2), formula (3) to calculate respectively the solubility of oil gas;

3. utilize formula (4) calculation interface tension force;

$P=\frac{\mathrm{RT}}{v-b}-\frac{a\left(T\right)}{v(v+b)+b(v-b)}$ Formula (1)

${\mathrm{\δ}}_{\mathrm{oll}}={\left[\frac{a\left(T\right)(1+\mathrm{\κ}\·T_r^{0.5})}{v(v+b)+b(v-b)}\left(\frac{1+\mathrm{\κ}-k{T}_r^{0.5}}{{[1+k(1-T_r^{0.5})]}^2}\right)\right]}^{0.5}$ Formula (2)

${\mathrm{\δ}}_{\mathrm{gas}}=1.25{\left(P_C\right)}^{0.5}\frac{{\mathrm{\ρ}}_r}{{\mathrm{\ρ}}_r\left(\mathrm{liq}\right)}$ Formula (3)

σ=δ ²V ^0.33/ A formula (4)

Reflect the cross section tension force at five different sampling spots places among Fig. 1 among Fig. 2, can characterize out natural core preferably in the process of displacement, the difference between the tension force of diverse location cross section.The validity of the method is described, also can changes for studying from now on natural core median surface tension field, an effectively experimental technique is provided, provide a kind of possibility for studying from now on the tension field variation of natural porous media median surface.

The above only is the schematic embodiment of the present invention, is not to limit scope of the present invention.For each ingredient of the present invention can make up under the condition of not conflicting mutually, any those skilled in the art, the equivalent variations of having done under the prerequisite that does not break away from design of the present invention and principle and modification all should belong to the scope of protection of the invention.

Claims (9)

1. the oil-gas interface tension test method in the porous medium is characterized in that, the oil-gas interface tension test method in the described porous medium comprises:

A, in the sample that porous medium forms, carry out displacement test to obtain the oil gas sample;

B, the oil gas sample that obtains is carried out stratographic analysis obtaining the oil gas chromatographic component, obtain oil gas interface tension force in the porous medium by the oil gas chromatographic component.

2. the oil-gas interface tension test method in the porous medium as claimed in claim 1 is characterized in that, the sample that described porous medium forms is natural core, uses carbon dioxide or nitrogen as displacement gas in the described displacement test.

3. the oil-gas interface tension test method in the porous medium as claimed in claim 1 is characterized in that, the length direction of the sample that forms along described porous medium arranges a plurality of sampling spots, with the oil gas sample at the different cross section place that obtains described sample.

4. the oil-gas interface tension test method in the porous medium as claimed in claim 2, it is characterized in that, oil-gas interface tension test method in the described porous medium uses the oil-gas interface tension test device in the porous medium to test, and the oil-gas interface tension test device in the described porous medium comprises: driving device, the sampler that is connected with driving device and the on-line chromatograph analytical equipment that is connected with sampler.

5. the oil-gas interface tension test method in the porous medium as claimed in claim 4, it is characterized in that, described driving device comprises: core holding unit, be provided with cavity fixing and the sealing natural core, and described core holding unit has import and the outlet that is connected with cavity; The displacement pipeline, by the import connection natural core of core holding unit, the displacement pump, the oil that displacement is used and displacement gas are pumped into respectively in the displacement pipeline; Oil tank and displacement gas storage tank have respectively the volume that holds the used oil of displacement and displacement gas, and described oil tank and displacement gas storage tank are connected in parallel between displacement pump and the displacement pipeline; Discharge pipe is connected with the outlet of described core holding unit; Check valve is arranged on the described discharge pipe.

6. the oil-gas interface tension test method in the porous medium as claimed in claim 5 is characterized in that, described sampler comprises: stopple coupon, extend in the described core holding unit, and be connected along the length direction setting of vertical natural core and with natural core; Valve and filtrator are connected in series with described stopple coupon.

7. the oil-gas interface tension test method in the porous medium as claimed in claim 6, it is characterized in that, described on-line chromatograph analytical equipment is the on-line chromatograph analyser, described driving device also comprises: be horizontally set on the natural core in the core holding unit, described stopple coupon is a plurality of, one end of described a plurality of stopple coupons is disposed on the different cross section place of natural core along the length direction of natural core, the other end of described a plurality of stopple coupons is in parallel with the on-line chromatograph analyser.

8. the oil-gas interface tension test method in the porous medium as claimed in claim 7, it is characterized in that, described natural core is bar-shaped, length is 30cm to 100cm, described stopple coupon is 5, be respectively the first stopple coupon, the second stopple coupon, the 3rd stopple coupon, the 4th stopple coupon and the 5th stopple coupon, each stopple coupon spaced set, each stopple coupon is connected in series with valve and filtrator.

9. the oil-gas interface tension test method in the porous medium as claimed in claim 8 is characterized in that, described method of testing specifically may further comprise the steps:

(1) sets check valve pressure;

(2) make the used oil of displacement enter core holding unit and natural core from the displacement pipeline by the displacement pump, make the displacement pump be made as pressure constant state, pressure is higher than check valve set pressure 0.5MPa, and makes the oil volume that enters natural core reach 3 times of multiple of active porosity volume;

(3) stop to make the used oil of displacement to enter core holding unit from the displacement pipeline, utilize the displacement pump to keep core holding unit pressure to be higher than check valve set pressure 0.5MPa, then carry out carbon dioxide displacement process;

(4) displacement is opened the valve that is connected with the first stopple coupon to the active porosity volume of setting multiple, makes oil gas sample in the first stopple coupon enter the on-line chromatograph analyser and obtains oil gas chromatographic component in the first stopple coupon, then closes the first stopple coupon;

(5) open the valve that is connected with the second stopple coupon, make oil gas sample in the second stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the second stopple coupon, then close the second stopple coupon;

(6) open the valve that is connected with the 3rd stopple coupon, make oil gas sample in the 3rd stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the 3rd stopple coupon, then close the 3rd stopple coupon;

(7) open the valve that is connected with the 4th stopple coupon, make oil gas sample in the 4th stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the 4th stopple coupon, then close the 4th stopple coupon;

(8) open the valve that is connected with the 5th stopple coupon, make oil gas sample in the 5th stopple coupon enter the on-line chromatograph analyser and obtain oil gas chromatographic component in the 5th stopple coupon, then close the 5th stopple coupon.

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