CN102914485B - Device and method for testing deviation factor of natural gas in porous medium - Google Patents

Abstract

The invention relates to a device and method for measuring the deviation factor of natural gas in a porous medium. The device is composed of a porous medium system, a data acquisition and processing system, a PVT test unit, an intermediate container, a gas meter, an oven, and a pump. The porous medium system consists of 5 Sand filling pipes are connected in series. The method comprises: filling quartz sand into five sand-filling pipes; measuring the pore volume of the sand-filling pipes and the volume of the pipeline between the pressure sensors; heating the oven to the formation temperature T; measuring the equilibrium pressure P in the first sand-filling pipe _and Equilibrium pressures P ₂ , P ₃ , P ₄ and P ₅ when connected in series with other sand packing pipes; the natural gas volumes V ₂ , V ₃ , V at pressures P ₂ , P ₃ , P ₄ and P ₅ are obtained through volume expansion _4. V ₅ ; Calculate the deviation factor of natural gas in porous media. The invention considers the influence of porous medium adsorption on the deviation factor of natural gas, so that the measurement result is closer to the deviation factor of real reservoir natural gas, and better guides production practice.

Description

Device and method for measuring deviation factor of natural gas in porous media

technical field

The invention relates to a device and method for measuring the deviation factor of natural gas in a porous medium, in particular to a device and a method for measuring the deviation factor of natural gas in consideration of the high temperature and high pressure environment of the porous medium of the reservoir in the oil and gas industry.

Background technique

The deviation factor of natural gas is one of the physical parameters of natural gas, which is mainly used for the calculation of geological reserves and recoverable reserves of gas reservoirs, well test analysis, productivity analysis, production dynamic analysis, numerical simulation, production system analysis, oil and gas production process design and surface engineering design. The currently known experimental method of natural gas deviation factor is to conduct experimental tests in the conventional PVT test unit without considering the porous medium environment of the reservoir. However, natural gas is in the porous medium of the reservoir, which will lead to a deviation between the deviation factor of conventional natural gas and the deviation factor of natural gas under real reservoir conditions.

Therefore, it is of great practical and guiding significance to study the experimental measurement device and method of natural gas deviation factor considering the high temperature and high pressure environment of porous media in reservoirs: (1) Considering the characteristics of large specific area of porous media and more significant adsorption; (2 ) takes into account the influence of the adsorption of porous media on the natural gas deviation factor, so that the measurement results are closer to the deviation factor of real reservoir natural gas, and better guide production practice.

Contents of the invention

The purpose of the present invention is to provide a device for measuring the deviation factor of natural gas in porous media. The device is reliable in principle, reasonable in structure, and simple to operate. Due to consideration of the porous medium of the reservoir and the high temperature and high pressure environment, the deviation factor of natural gas measured by the device is better. The deviation factor close to the real reservoir natural gas is beneficial to guide the production practice.

Another object of the present invention is to provide a method for measuring the deviation factor of natural gas in porous media by using the above-mentioned device. The deviation factor of natural gas tested by the method more truly reflects the influence of the existence of porous media in the reservoir on the deviation factor of natural gas.

The invention can not only be used for the experimental research on the deviation factor of natural gas under the high temperature and high pressure environment of porous media, but also for the experimental test of other physical parameters (volume coefficient, thermal expansion coefficient, etc.) of natural gas. The experimental method can achieve a maximum pressure of 100MPa and a maximum temperature of 200°C.

In order to achieve the above technical objectives, the present invention provides the following technical solutions.

A device for measuring the deviation factor of natural gas in a porous medium, mainly composed of a porous medium system, a data acquisition and processing system, a PVT test unit, an intermediate container, a gas meter, an oven, and a pump, and the porous medium system consists of 5 sand filling pipes Formed in series, the porous medium system is connected to the PVT test unit and the intermediate container respectively, the PVT test unit and the intermediate container are respectively connected to the pump, the porous medium system and the PVT test unit are placed in an oven and connected to a gas meter; The data acquisition and processing system includes a temperature sensor, a pressure sensor and a computer. The porous medium system is connected to the computer through the temperature sensor and the pressure sensor. The temperature sensor and the pressure sensor monitor the temperature and pressure in the sand filling pipe and transmit the data to computer; valves are provided between the sand filling pipes of the porous medium system, between the porous medium system and the PVT test unit, and between the intermediate containers.

The method for determining the deviation factor of natural gas in porous media by using the above-mentioned device comprises the following steps in sequence:

(1) Fill quartz sand with different meshes into 5 sand filling tubes respectively, and the maximum pressure that the sand filling tubes can bear is 100MPa;

(2) Under standard conditions (P ₀ =0.1MPa, T ₀ =20°C), measure the pore volume of each sand-packing pipe in turn by pumping N ₂ as V _K1 , V _K2 , V _K3 , V _K4 , V _K5 , the volume of the pipeline connecting the sand filling pipe to the pressure sensor is V _c , then discharge N ₂ and use a vacuum pump to evacuate the sand filling pipe and pipeline to a vacuum state (because the pipeline between the sand filling pipes in series is short and the inner diameter is small, the connection between the sand filling pipes The pipeline volume is negligible);

(3) Set the temperature of the oven to the formation temperature T of the reservoir through the computer and raise the temperature to the formation temperature T;

(4) Use a pump to fill the first sand filling pipe with the natural gas in the intermediate container. When the pump enters slowly, monitor the pressure in the first sand filling pipe through the pressure sensor. When the pressure is balanced, record the first sand filling pipe at this time The equilibrium pressure P ₁ ;

(5) Transfer part of the natural gas absorbed by the first sand filling pipe into the PVT test unit, and use a pump to adjust the pressure of the natural gas in the PVT test unit to P ₁ , so as to obtain the volume V ₁₁ of the natural gas under the conditions of T and P ₁ , and then keep the pressure at P ₁ , discharge part of the natural gas in the PVT test unit into the gas meter, and use the gas meter to measure the volume of the natural gas under standard conditions (P ₀ =0.1MPa, T ₀ =20°C) V ₀ , and then read the natural gas volume V ₁₂ in the PVT test unit after exhaust, so as to obtain the volume change value of natural gas under the conditions of T and P ₁ as V ₁ (V ₁ =V ₁₁ -V ₁₂ ), using the following The gas equation of state:

P _O V _O =nRZ ₀ T ₀ (where Z _O =1)

P ₁ V ₁ =nRZ ₁ T,

So as to get the deviation factor of the gas in the PVT test unit

(6) Use a vacuum pump to evacuate the first sand-filling pipe to a vacuum state, then use the pump to fill the first sand-filling pipe with natural gas in the intermediate container, and open the valve between the first sand-filling pipe and the second sand-filling pipe to make the first sand-filling pipe The sand filling pipe and the second sand filling pipe are kept connected, and the balance pressure P ₂ when the first sand filling pipe and the second sand filling pipe are connected in series is monitored by a pressure sensor;

(7) Open the valve between the second sand filling pipe and the third sand filling pipe, monitor the balance pressure P ₃ when the first sand filling pipe, the second sand filling pipe and the third sand filling pipe are connected in series, and open the third filling pipe. The valve between the sand filling pipe and the fourth sand filling pipe, monitor the balance pressure P ₄ when the first sand filling pipe, the second sand filling pipe, the third sand filling pipe and the fourth sand filling pipe are connected in series, and open the fourth sand filling pipe The valve between the pipe and the fifth sand filling pipe monitors the balance pressure P ₅ when the first sand filling pipe, the second sand filling pipe, the third sand filling pipe, the fourth sand filling pipe and the fifth sand filling pipe are connected in series;

(8) In the PVT test unit, do volume expansion experiments on the remaining gas at the pressure points P ₂ , P ₃ , P ₄ and P ₅ to obtain the pressures at P ₂ , P ₃ , P ₄ and P ₅ respectively. Natural gas volume V ₂ , V ₃ , V ₄ , V ₅ ;

(9) Use the gas state equation to obtain the deviation factor of natural gas in the PVT test unit and porous media through the following formula:

1) Bias factor Z _i of natural gas in PVT test unit

Deviation factor for the 1st pressure point:

Deviation factors for the 2nd, 4th, and 5th pressure points:

Note: V _i-1 is the volume of natural gas in the PVT test unit at the i-1th pressure point and under the formation temperature; V _i is the volume of natural gas in the PVT test unit at the i-th pressure point and under the formation temperature .

2) The deviation factor Z′ ₁ of natural gas in porous media

The deviation factor of the first pressure point: Z′ ₁ =Z ₁

Deviation factors for the 2nd, 3rd, 4th, and 5th pressure points:

Note: V′ ₁ =V _c +V _k1

V′ ₂ =V _c +V _k1 +V _k2 ,

and so on, $V_i^{\&prime;}=V_c+{\mathrm{<figure-callout\; id="1"\; label="V\; K"\; filenames="HDA00002350278400012.png"\; state="\{\{state\}\}">V</figure-callout>}}_K+\underset{i=2}{\overset{5}{\mathrm{\&Sigma;}}}{V}_{\mathrm{Ki}}.$

Compared with the prior art, the present invention has the following beneficial effects:

(1) The measuring device involved in the present invention has a reliable principle, a reasonable structure, and is easy to operate. The device can accurately measure the deviation factor of natural gas in a high-temperature and high-pressure environment in a porous medium of a reservoir;

(2) The deviation factor of natural gas under the condition of considering porous media and not considering porous media can be tested at the same time;

(3) The deviation factor of the natural gas under the porous medium condition of the tested reservoir is closer to the deviation factor of the real reservoir natural gas;

(4) The maximum temperature and pressure that can be achieved in the experiment is 100MPa, and the maximum temperature is 200°C.

Description of drawings

Fig. 1 is a structural schematic diagram of the device for measuring the deviation factor of natural gas in porous media according to the present invention.

In Fig. 1: 1, the first sand filling pipe; 2, the second sand filling pipe; 3, the third sand filling pipe; 4, the fourth sand filling pipe; 5, the fifth sand filling pipe; 6, the valve; 7, Pressure sensor; 8, computer; 9, temperature sensor; 10, PVT test unit; 11, pump one; 12, pump two; 13, gas meter; 14, intermediate container; 15, oven.

Figure 2 is a comparison chart of natural gas deviation factors considering porous media and not considering porous media.

Detailed ways

Further illustrate the present invention below in conjunction with accompanying drawing.

See Figure 1. A device for measuring the deviation factor of natural gas in a porous medium, mainly composed of a porous medium system, a data acquisition and processing system, a PVT test unit 10, an intermediate container 14, a gas meter 13, and an oven 15. The porous medium system consists of a first filling The sand pipe 1, the second sand pipe 2, the third sand pipe 3, the fourth sand pipe 4, and the fifth sand pipe 5 are connected in series, and the porous medium system is connected with the PVT test unit 10 and the intermediate container 14 respectively. Connected, the PVT test unit 10 and the intermediate container 14 are respectively connected with a pump one 11 and a pump two 12, and the porous medium system and the PVT test unit 10 are placed in an oven 15 and connected to a gas meter 13; the data collection and processing The system includes a temperature sensor 9, a pressure sensor 7 and a computer 8. The porous media system is connected to the computer 8 through the temperature sensor 9 and the pressure sensor 7; between the sand filling pipes of the porous media system, the porous media system and the PVT test unit All have valve 6 between, intermediate container.

The method for measuring the deviation factor of natural gas in porous media described by the above-mentioned device includes in turn:

1. Fill the quartz sand with different meshes into 5 sand filling tubes respectively;

2. At 20°C and 0.1MPa, use pump 12 to inject N ₂ to measure the pore volumes V _K1 , V _K2 , V _K3 , V _K4 , and V _K5 of the first to fifth sand filling tubes are 89.14ml in turn. , 16.62ml, 24.56ml, 55.45ml, 92.44ml, the volume V _c of the pipeline between the sand filling tubes connected to the pressure sensor is 2ml, and then evacuate the 5 sand filling tubes;

3. Set and raise the temperature of the oven to the reservoir formation temperature of 80°C through the computer;

4. Use the pump to fill the first sand filling pipe with the natural gas in the intermediate container. When the pump enters slowly, monitor the pressure in the first sand filling pipe through the pressure sensor. When the pressure is balanced, record the current in the first sand filling pipe. The pressure P ₁ is 42.34MPa;

5. Transfer part of the natural gas absorbed by the first sand filling pipe into the PVT test unit, and use the pump 11 to adjust the pressure of the natural gas in the PVT test unit to P ₁ , so as to measure the volume of the natural gas at 80°C and 42.34MPa V ₁₁ is 25.250ml, and then under the condition of keeping the pressure at 42.34MPa, part of the natural gas in the PVT test unit is discharged into the gas meter, and the natural gas is measured under standard conditions (P ₀ =0.1MPa, T ₀ =20°C) The volume V ₀ of the gas is 225ml, and then the volume V ₁₂ of the natural gas in the PVT test unit after exhaust is read as 25.110ml, so as to obtain the volume change value V ₁ of the natural gas under the conditions of T and P ₁ (V ₁ =V ₁₁ -V ₁₂ ) is 0.140ml, so the deviation factor of gas is 0.984;

6. Use a vacuum pump to evacuate the first sand filling pipe to a vacuum state, then use the pump 12 to fill the first sand filling pipe with natural gas in the intermediate container, and open the valve between the first sand filling pipe and the second sand filling pipe to make the first sand filling pipe The sand filling pipe and the second sand filling pipe are kept connected, and the balance pressure P ₂ when the first sand filling pipe and the second sand filling pipe are connected in series is monitored by the pressure sensor, which is 32.40MPa; open the second sand filling pipe and the third The valve between the sand pipes, monitor the balance pressure P ₃ when the first sand pipe, the second sand pipe and the third sand pipe are connected in series to be 25.10MPa, open the valve between the third sand pipe and the fourth sand pipe The valve is used to monitor the balance pressure P ₄ of the first sand filling pipe, the second sand filling pipe, the third sand filling pipe and the fourth sand filling pipe in series, which is 17.33MPa, and the fourth sand filling pipe and the fifth sand filling pipe are opened Between the valves, monitor the balance pressure P ₅ when the first sand filling pipe, the second sand filling pipe, the third sand filling pipe, the fourth sand filling pipe and the fifth sand filling pipe are connected in series to be 11.86MPa;

7. In the PVT test unit, _the volume expansion experiment of _the remaining gas is carried out, and the natural gas volume _{V 2 is} 35.320ml, V ₃ is _48.295ml , and V ₄ is 71.865ml, V ₅ is 102.685ml, so the deviation factors of natural gas under high temperature and high pressure conditions considering porous media and not considering porous media (PVT test unit) are obtained. The results are shown in Table 1 and Figure 2.

Table 1 Comparison table of natural gas deviation factors considering porous media and not considering porous media

Pressure (MPa) Does not consider porous media Consider porous media 42.34 0.984 0.984 32.40 0.914 0.890 25.10 0.863 0.847 17.33 0.840 0.830 11.86 0.859 0.842

Claims (2)

1. the determinator of rock gas deviation factors in a porous medium, mainly by porous medium system, data acquisition and processing system, PVT test cell (10), intermediate receptacle (14), gasometer (13), baking oven (15) forms, it is characterized in that, described porous medium system is by the first fill out sand tube (1), the second fill out sand tube (2), the 3rd fill out sand tube (3), the 4th fill out sand tube (4), the 5th fill out sand tube (5) is in series, described porous medium system is connected with intermediate receptacle (14) with PVT test cell (10) respectively, described PVT test cell (10) and intermediate receptacle (14) are connected with respectively pump one (11), pump two (12), described porous medium system is placed in baking oven (15) and is connected gasometer (13) with PVT test cell, described data acquisition and processing system comprises temperature sensor (9), pressure transducer (7) and computing machine (8), and described porous medium system is connected with computing machine (8) by temperature sensor (9), pressure transducer (7), between the fill out sand tube of described porous medium system, between porous medium system and PVT test cell, between intermediate receptacle, all have a valve (6).

2. utilize device as claimed in claim 1 to measure the method for rock gas deviation factors in porous medium, comprise the following steps successively:

(1) silica sand of different meshes is filled into respectively in 5 fill out sand tube;

(2) at P ₀=0.1MPa, T ₀at=20 ℃, with pump two (12), note N ₂measure successively every fill out sand tube volume of voids and be respectively V _k1, V _k2, V _k3, V _k4, V _k5, between fill out sand tube Bonding pressure sensor, the volume of pipeline is V _c, then discharge N ₂and find time fill out sand tube and pipeline to vacuum state with vacuum pump;

(3) by computing machine, the Temperature Setting of baking oven is become to the formation temperature T of reservoir and is warming up to formation temperature T;

(4) with pump two (12), the rock gas of intermediate receptacle is full of to the first fill out sand tube, by the pressure in pressure sensor monitoring the first fill out sand tube, when pressure equilibrium, writes down the pressure P in the first fill out sand tube now ₁;

(5) will proceed in PVT test cell through the first fill out sand tube absorption a part of rock gas later, with pump one (11), regulating the pressure of rock gas in PVT test cell is P ₁, obtain rock gas at T, P ₁volume V under condition ₁₁, maintenance pressure is P ₁, the rock gas part in PVT test cell is discharged in gasometer, measure rock gas at P ₀=0.1MPa, T ₀volume V at=20 ℃ ₀, then read the rock gas volume V in PVT test cell after exhaust ₁₂, obtain rock gas at T, P ₁volume change value V under condition ₁=V ₁₁-V ₁₂thereby, obtain the deviation factors of gas in PVT test cell

(6) with vacuum pump, find time the first fill out sand tube to vacuum state, then use pump two (12) that the rock gas of intermediate receptacle is full of to the first fill out sand tube, open the valve between the first fill out sand tube and the second fill out sand tube, make the first fill out sand tube and the second fill out sand tube keep UNICOM's state, and the equalized pressure P during by pressure sensor monitoring the first fill out sand tube and the series connection of the second fill out sand tube ₂;

(7) open the valve between the second fill out sand tube and the 3rd fill out sand tube, the equalized pressure P while monitoring the first fill out sand tube, the second fill out sand tube and the series connection of the 3rd fill out sand tube ₃, open the valve between the 3rd fill out sand tube and the 4th fill out sand tube, the equalized pressure P while monitoring the first fill out sand tube, the second fill out sand tube, the 3rd fill out sand tube and the series connection of the 4th fill out sand tube ₄, open the valve between the 4th fill out sand tube and the 5th fill out sand tube, the equalized pressure P while monitoring the first fill out sand tube, the second fill out sand tube, the 3rd fill out sand tube, the 4th fill out sand tube and the series connection of the 5th fill out sand tube ₅;

(8) in PVT test cell, remaining gas is done to volumetric expansion experiment, obtain pressure and be respectively P ₂, P ₃, P ₄and P ₅time rock gas volume V ₂, V ₃, V ₄, V ₅;

(9) utilize following formula to obtain the deviation factors Z ' of rock gas in porous medium ₁:

The deviation factors of the 1st spot pressure: Z ' ₁=Z ₁

2nd, the deviation factors of 3,4,5 spot pressures:

V′ ₁＝V _c+V _K1

V′ ₂＝V _c+V _K1+V _K2

${V_i}^{\&prime;}=V_c+V_{K1}+\underset{i=2}{\overset{5}{\mathrm{\&Sigma;}}}{V}_{\mathrm{Ki}}.$

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