CN115165952B - Gas-water two-phase saturated rock core high-temperature high-pressure nuclear magnetic resonance experimental measurement method and device - Google Patents

Abstract

The invention discloses a high-temperature high-pressure nuclear magnetic resonance experimental measurement method and device. The high-temperature high-pressure nuclear magnetic resonance experiment measuring method beneficial to the device can accurately control the gas-water saturation, can apply and control pore pressure and avoid the change of the gas-water saturation when the nuclear magnetic resonance high-temperature high-pressure experiment is carried out, and meets the requirement of carrying out the physical simulation experiment of the natural gas reservoir in a room.

Description

Gas-water two-phase saturated core high temperature and high pressure NMR experimental measurement method and device

technical field

The invention belongs to the technical field of petroleum and natural gas supporting exploration, and relates to a rock physics nuclear magnetic resonance experimental method, in particular to a high-temperature and high-pressure nuclear magnetic resonance experimental measurement method and device for a gas-water two-phase saturated rock core.

Background technique

NMR is an effective means to obtain rock sample physical properties, pore structure, T2 cut-off value and other parameters. In order to obtain the NMR response characteristics of oil and gas reservoirs under the conditions of formation temperature, pressure, and oil-water saturation, the existing high-temperature and high-pressure NMR usually uses oil-displacement water or water-displacement oil under the confining pressure and temperature conditions of the core. Change the oil-water saturation of the core and collect nuclear magnetic resonance signals. In this case, the outlet port is allowed to open to the atmosphere (atmospheric pressure is 0.1MPa), that is, no back pressure is added for experimental measurement, as shown in Figure 1.

Due to the huge difference in hydrogen index between natural gas and crude oil, the NMR response characteristics of gas reservoirs cannot be measured with oil-water two-phase saturated cores. At the same time, due to the good compressibility of the gas and the volume expansion after heating, it is impossible to directly use the existing device to measure (as shown in Figure 1) to obtain the NMR signal of the natural gas reservoir under high temperature and high pressure conditions. On the one hand, when the formation water is replaced by gas to change the gas saturation, high pore pressure cannot be established to simulate the formation pressure because no back pressure is added to the atmosphere at the outlet (atmospheric pressure is 0.1 MPa). On the other hand, opening the outlet to the atmosphere will cause the volume of the gas to expand when heated and change the gas saturation. These two problems make it impossible to measure the NMR signals of natural gas reservoirs under high-temperature and high-pressure conditions with oil-displacement water methods and devices. Therefore, it is urgent to establish new experimental methods and devices to accurately obtain gas-water two-phase cores in The nuclear magnetic resonance signal under high temperature and high pressure provides an accurate petrophysical experimental basis for the interpretation and evaluation of nuclear magnetic resonance logging in natural gas reservoirs.

Contents of the invention

In order to solve the above technical problems, the present invention provides a high temperature and high pressure nuclear magnetic resonance experiment measurement method and device, the method and device can accurately control the gas-water saturation, and can apply and control the pore pressure during the high temperature and high pressure nuclear magnetic resonance experiment. It avoids the change of gas-water saturation and meets the needs of carrying out physical simulation experiments of natural gas reservoirs indoors.

In order to achieve the above object, the present invention adopts the following technical solutions:

A high-temperature and high-pressure nuclear magnetic resonance experiment measurement device, including a computer, a nuclear magnetic resonance measuring instrument, a magnet box with a built-in non-magnetic core holder, a core sample, a confining pressure intermediate container, a confining pressure pump, a pore intermediate container, a pore pressure pump, and a return Control pressure pump and measuring cylinder;

One side of the nuclear magnetic resonance measuring instrument is connected to the computer, and the other side is connected to the non-magnetic core holder in the magnet box;

The non-magnetic core holder has a built-in core sample;

Both sides of the non-magnetic core holder are respectively connected to a confining pressure intermediate container through a confining pressure valve, and the confining pressure intermediate container is connected to a confining pressure pump;

The inlet end and the outlet end of the non-magnetic core holder are respectively connected to a pore intermediate container through a pore pressure valve, and the pore intermediate container is connected to a pore pressure pump;

The outlet end of the non-magnetic core holder is connected to the return control pressure pump through the return control pressure valve, and the return control pressure valve is connected to the measuring cylinder.

Preferably, the magnetic core holder, the confining pressure intermediate container and the confining pressure valve are connected by metal non-magnetic pipelines.

Preferably, the confining pressure intermediate container is connected with a temperature controller.

Preferably, there are two confining pressure intermediate vessels, including No. 1 confining pressure intermediate vessel and No. 2 confining pressure intermediate vessel.

Further preferably, the confining pressure intermediate container is filled with fluorine oil.

Preferably, the porous intermediate vessel is filled with brine or methane gas.

The present invention also provides a high-temperature and high-pressure nuclear magnetic resonance experimental measurement method, which uses the above-mentioned high-temperature and high-pressure nuclear magnetic resonance experimental measurement device to measure rock core samples.

Preferably, the high temperature and high pressure nuclear magnetic resonance experimental measurement method comprises the following steps:

S1. Fill the No. 1 confining pressure intermediate container and No. 2 confining pressure container with fluorine oil, turn on the temperature controller, and heat the fluorine oil to the formation temperature;

S2. Put the pretreated rock core sample into the nonmagnetic rock core holder in the magnet box, adjust the pressure of the confining pressure pump, and apply confining pressure to the rock core sample;

S3. Adjust the return control pressure pump so that the return control pressure valve reaches the preset pressure, and the water or gas in the pipeline at the outlet end flows into the measuring cylinder through the pipeline.

S4. Fill brine into the pore intermediate container, open the pore pressure valve, adjust the pore pressure pump, apply pressure to both ends of the core sample, and close the pore pressure valve after reaching the preset pressure.

S5. Adjust the pressure values of No. 1 confining pressure pump, No. 2 confining pressure pump and pore pressure pump, apply confining pressure to the core sample with fluorine oil, apply pore pressure to the core sample with salt water, and maintain the pressure difference between confining pressure and pore pressure Less than 10Mpa, and gradually increase the pressure to the formation pressure P;

S6. Adjust the pressure P1 of the No. 1 confining pressure pump, so that the No. 1 confining pressure pump and the No. 2 confining pressure pump generate a confining pressure difference ΔP, and drive the liquid in the No. 2 confining pressure intermediate container to pass through the confining pressure chamber of the non-magnetic core holder body into the No. 1 confining pressure intermediate container;

S7. When all the fluorine oil in the No. 2 confining pressure intermediate container enters the No. 1 confining pressure intermediate container, adjust the pressure of the No. 1 confining pressure pump to the formation pressure P, and set the pressure of the No. 2 confining pressure pump to P2', Under the action of pressure difference, the fluorine oil in the No. 1 confining pressure intermediate container enters into the No. 2 confining pressure intermediate container through the confining pressure cavity of the non-magnetic core holder;

S8. Steps S6 and S7 are repeated to keep the temperature in the confining pressure cavity of the non-magnetic core holder at the formation temperature;

S9, collecting the high temperature and high pressure nuclear magnetic resonance parameters of the rock core sample in the state of saturated brine;

S10, put white oil in the graduated cylinder;

S11. Fill the pore intermediate container with methane gas, open the inlet pore pressure valve, close the outlet pore pressure valve, adjust the return control pressure pump to an appropriate pressure, open the return control pressure valve, and the water or gas in the outlet pipeline flows into the measuring cylinder through the pipeline ;

S12. According to the physical properties of the core, adjust the pore pressure pump to an appropriate displacement pressure, and drive the methane gas in the pore intermediate container to displace the core sample to an appropriate water saturation or gas saturation. Gas volume, calculate core water saturation or gas saturation;

S13. Steps S5, S6 and S7 are repeated to restore the temperature, confining pressure and pore pressure to the formation conditions, and collect high temperature and high pressure NMR parameters of the gas-water two-phase saturated core.

Further preferably, the pretreatment of the core sample in step S2 is as follows: after the core sample is washed with oil and dried, the saturated brine is vacuumed and pressurized, and the porosity of the core is calculated according to the dry weight, wet weight and buoyant weight of the rock sample. volume, total volume and porosity.

Further preferably, the formula for calculating the pressure P1 of the No. 1 confining pressure pump in step S6 is: P1=P-0.5Mpa.

Further preferably, the formula for calculating the confining pressure difference ΔP in step S6 is: ΔP=P2-P1, wherein P2 is the pressure of the No. 2 confining pressure pump.

Further preferably, the calculation formula of P2' described in step S7 is: P2'=P-0.5Mpa.

The beneficial effects of the present invention are:

In view of the fact that there is no feasible high-temperature and high-pressure nuclear magnetic resonance experimental measurement method that can avoid the change of gas-water saturation, the present invention provides a method that can control the gas-water saturation, pore pressure, and temperature of the core and avoid gas-water two-phase saturated rock. A high temperature and high pressure nuclear magnetic resonance experimental measurement method and device for heart gas water saturation change. A sandstone plug sample from a certain depth section was selected, based on the high-temperature and high-pressure nuclear magnetic resonance experiment of gas-water two-phase saturated core, using the characteristics that fluorine oil does not contain hydrogen nuclei and does not generate nuclear magnetic signals, fluorine oil is used as confining pressure application and heat transfer The medium is to heat the two intermediate containers distributed at both ends of the core and to control the temperature of the core through the reciprocating motion of the heated fluorine oil in the two intermediate containers. Methane gas is used as the pore pressure application medium, and the return pressure control valve is set. The pressure limit realizes the simultaneous application of high pore pressure at both ends of the core, and finally measures the NMR T2 spectrum of the rock sample under high temperature and high pressure and different gas saturation states.

Description of drawings

Fig. 1 is the conventional oil-water two-phase saturated rock core high temperature and high pressure nuclear magnetic resonance experiment device figure of prior art;

Among them, 1. Confining pressure pump; 2. Pore pressure pump; 3. Confining pressure valve; 4. Pore pressure valve; 5. Metal pipeline; 6. Magnet box; 7. Core sample; 8. Graduated cylinder; 9. Data connection line ; 10, computer; 11, nuclear magnetic resonance measuring instrument.

Fig. 2 is experimental apparatus figure of the present invention;

Among them, 1, No. 1 confining pressure pump; 2, No. 2 confining pressure pump; 3, pore pressure pump; 4, No. 1 intermediate container; 5, No. 2 intermediate container; 6, pore intermediate container; 7, No. 1 confining pressure Valve; 8. No. 2 confining pressure valve; 9. Inlet pore pressure valve; 10. Outlet pore pressure valve; 11. Return control pressure valve; 12. Measuring cylinder; 13. Metal non-magnetic pipeline; 14. Magnet box; 15. Rock core Sample; 16. Data connection line; 17. Computer; 18. Nuclear magnetic resonance measuring instrument; 19. Temperature controller; 20. Return control pressure pump.

Fig. 3 is a flow chart of the method of the present invention.

Fig. 4 is the T2 spectrogram of the embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described below in conjunction with specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

Before further describing the specific embodiments of the present invention, it should be understood that the protection scope of the present invention is not limited to the following specific specific embodiments; it should also be understood that the terms used in the examples of the present invention are to describe specific specific embodiments, It is not intended to limit the protection scope of the present invention.

As shown in Figure 2, the present invention provides a kind of high-temperature high-pressure nuclear magnetic resonance experiment measurement device, comprises computer 17, nuclear magnetic resonance measuring instrument 18, the magnet box 14 of built-in non-magnetic rock core holder, rock core sample 15, No. 1 confining pressure Intermediate container 4, No. 2 confining pressure intermediate container 5, No. 1 confining pressure pump 1, No. 2 confining pressure pump 2, pore intermediate container 6, pore pressure pump 3, return control pressure pump 20 and measuring cylinder 12;

One side of the nuclear magnetic resonance measuring instrument 18 is connected with the computer 17, and the other side is connected with the non-magnetic core holder in the magnet box 14;

The non-magnetic core holder has a built-in core sample 15;

The two sides of the non-magnetic core holder are respectively connected to No. 1 confining pressure intermediate container 4 and No. 2 confining pressure intermediate container 5 through No. 1 confining pressure valve 7 and No. 2 confining pressure valve 8. The No. 1 confining pressure The intermediate container 4 and the No. 2 confining pressure intermediate container 5 are connected to the corresponding No. 1 confining pressure pump 1 and No. 2 confining pressure pump 2;

The inlet end and the outlet end of the non-magnetic core holder are respectively connected to the pore intermediate container 6 through the inlet pore pressure valve 9 and the outlet pore pressure valve 10, and the pore intermediate container 6 is connected to the pore pressure pump 3;

The outlet end of the non-magnetic core holder is connected to the return control pressure pump 20 through the return control pressure valve 11 , and the return control pressure valve 11 is connected to the measuring cylinder 12 .

Preferably, the magnetic core holder, the confining pressure intermediate container and the confining pressure valve are connected through a metal non-magnetic pipeline 13 .

Preferably, the confining pressure intermediate container is connected with a temperature controller 19 .

Preferably, the confining pressure intermediate container is filled with fluorine oil.

Preferably, the porous intermediate vessel is filled with brine or methane gas.

The present invention also provides a high-temperature and high-pressure nuclear magnetic resonance experimental measurement method, which uses the above-mentioned high-temperature and high-pressure nuclear magnetic resonance experimental measurement device to measure rock core samples. Taking well A of a certain oil reservoir as an example, the method and device proposed by the present invention will be described in detail in conjunction with FIG. 3 and specific embodiments.

Example 1

A high temperature and high pressure nuclear magnetic resonance experimental measurement method, its specific method comprises the following steps:

S1. Select 5 sandstone plunger samples at a certain depth. After the rock samples are washed with oil and dried, they are vacuumed and pressurized with saturated brine. Calculate the pore volume, total volume and porosity of the core sample according to the dry weight, wet weight and buoyant weight of the rock sample;

S2. Fill the No. 1 confining pressure intermediate vessel 4 and No. 1 confining pressure intermediate vessel 5 with fluorine oil, turn on the temperature controller 19, set the temperature to the formation temperature of 80°C, and fill the No. 1 confining pressure intermediate vessel 4 and No. 1 The fluorine oil in the confining pressure intermediate container 5 is heated to a formation temperature of 80°C;

S3, put the rock core sample of saturated brine into the holder of the device of the present invention, adjust the pressure of No. 1 confining pressure pump 1 and No. 2 confining pressure pump 2 to 3MPa, and drive the fluorine oil in the intermediate container to apply 3MPa confining pressure;

S4. Adjust the return control pressure pump 20 to 60MPa, and set the pressure limit for the return control pressure valve 11 to 60MPa;

S5. Fill the pore intermediate container 6 with brine with the same salinity, open the inlet pore pressure valve 9 and the outlet pore pressure valve 10, adjust the pressure of the pore pressure pump 3 to 0.5 MPa, and apply a pore pressure of 0.5 MPa at both ends of the core sample , close the inlet pore pressure valve 9 and the outlet pore pressure valve 10;

S6. Adjust the pressure values of No. 1 confining pressure pump 1, No. 2 confining pressure pump 2 and pore pressure pump 3. Under the condition that the difference between confining pressure and pore pressure is always kept less than 10MPa, increase the confining pressure to 58MPa and increase the pore pressure. Up to 50MPa;

S7. Adjust the pressure of No. 1 confining pressure pump 1 to 57.5MPa. At this time, the pressure difference between No. 2 confining pressure pump 2 and No. 1 confining pressure pump 1 is 0.5 MPa, and No. 2 confining pressure pump 2 starts to drive No. 2 confining pressure intermediate container The high-temperature liquid in 5 enters the No. 1 confining pressure intermediate container 4 through the confining pressure chamber of the holder;

S8. When all the fluorine oil in the No. 2 confining pressure intermediate container 5 enters the No. 1 confining pressure intermediate container 4, restore the pressure of the No. 1 confining pressure pump 1 to the formation pressure of 58 MPa, and set the pressure of the No. 2 confining pressure pump 2 to 57.5 MPa. At this time, due to the pressure difference, the liquid in the No. 1 confining pressure intermediate container 4 enters the No. 2 confining pressure intermediate container 5 through the clamper confining pressure chamber;

S9. Repeat S7 and S8 to keep the internal temperature of the holder at the set formation temperature of 80°C;

S10, collecting the high temperature and high pressure nuclear magnetic resonance parameters of the core sample 15 in the state of saturated brine;

S11, a small amount of white oil is loaded into the measuring cylinder 12 to ensure that the white oil immerses the outlet end of the displacement pipeline to prevent the gas (salt water) at the outlet end from diffusing into the air, resulting in inaccurate measurement of gas (water) saturation;

S12. Fill the gap intermediate container 6 with methane gas, open the inlet pore pressure valve 9, close the outlet pore pressure valve 10, adjust the pressure of the return control pressure pump 20 to 0.5 MPa, open the return control pressure valve 11, and the water in the outlet pipeline (gas) flows into the measuring cylinder 12 through the pipeline;

S13. Adjust the displacement pressure of the pore pressure pump 3 to 1 MPa, drive the methane gas in the pore intermediate container 6 to displace the core sample 15 to a suitable water (gas) saturation, according to the water output in the measuring cylinder 12 at the outlet end of the metering holder (gas) amount to calculate the water (gas) saturation of the core;

S14. Steps S6, S7 and S8 are repeated, the temperature, confining pressure and pore pressure are restored to the formation conditions, and the high-temperature and high-pressure NMR parameters of the gas-water two-phase saturated core are collected. The results are shown in FIG. 4 .

It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive, so the present invention includes and is not limited to the embodiments described in the specific implementation, and those skilled in the art according to the technology of the present invention Other implementations derived from the scheme also belong to the protection scope of the present invention.

Claims (2)

1. The high-temperature high-pressure nuclear magnetic resonance experimental measurement method is characterized by adopting a high-temperature high-pressure nuclear magnetic resonance experimental measurement device to measure a core sample and comprising the following steps of:

s1, filling fluorine oil into a confining pressure intermediate container 1 and a confining pressure container 2, and opening a temperature controller to heat the fluorine oil to the stratum temperature;

s2, placing the pretreated core sample into a non-magnetic core holder in a magnet box, adjusting the pressure of a confining pressure pump, and applying confining pressure to the core sample;

s3, adjusting a back control pressure pump to enable a back control pressure valve to reach preset pressure, and enabling water or gas in a pipeline at an outlet end to flow into a measuring cylinder through the pipeline;

s4, filling saline into the pore middle container, opening a pore pressure valve, adjusting a pore pressure pump, applying pressure to two ends of the core sample until the pressure reaches a preset pressure, and closing the pore pressure valve;

s5, adjusting pressure values of the confining pressure pump No. 1, the confining pressure pump No. 2 and the pore pressure pump, applying confining pressure to the core sample by using fluorine oil, applying pore pressure to the core sample by using brine, keeping the pressure difference between the confining pressure and the pore pressure to be less than 10Mpa, and gradually increasing the pressure to the formation pressure P;

s6, adjusting the pressure P1 of the confining pressure pump No. 1 to enable the confining pressure pump No. 1 and the confining pressure pump No. 2 to generate confining pressure difference delta P, and driving the liquid in the confining pressure intermediate container No. 2 to enter the confining pressure intermediate container No. 1 through the confining pressure cavity of the nonmagnetic core holder;

the calculation formula of the pressure P1 of the No. 1 confining pressure pump is as follows: p1=p-0.5 Mpa; the calculation formula of the confining pressure difference delta P is as follows: Δp=p2-P1, where P2 is the pressure of the No. 2 confining pressure pump;

s7, after all the fluorine oil in the confining pressure intermediate container No. 2 enters the confining pressure intermediate container No. 1, adjusting the pressure of the confining pressure pump No. 1 to be the formation pressure P, setting the pressure of the confining pressure pump No. 2 to be P2', and enabling the fluorine oil in the confining pressure intermediate container No. 1 to enter the confining pressure intermediate container No. 2 through the confining pressure cavity of the nonmagnetic core holder under the action of pressure difference;

wherein, the calculation formula of the P2' is as follows: p2' =p-0.5 Mpa;

s8, repeating the steps S6 and S7, so that the temperature in the confining pressure cavity of the non-magnetic core holder is always kept at the stratum temperature;

s9, collecting high-temperature high-pressure nuclear magnetic resonance parameters of a core sample in a saturated saline state;

s10, white oil is filled in the measuring cylinder;

s11, filling methane gas into a pore intermediate container, opening an inlet pore pressure valve, closing an outlet pore pressure valve, adjusting a back control pressure pump to proper pressure, opening the back control pressure valve, and enabling water or gas in an outlet end pipeline to flow into a measuring cylinder through a pipeline;

s12, adjusting a pore pressure pump to a proper displacement pressure according to physical properties of the core, driving methane gas in a pore middle container to displace the core sample to a proper water saturation or gas saturation, and calculating the water saturation or gas saturation of the core according to water yield or gas yield in a measuring cylinder;

s13, repeating the steps S5, S6 and S7, recovering the temperature, confining pressure and pore pressure to stratum conditions, and collecting high-temperature high-pressure nuclear magnetic resonance parameters of the gas-water two-phase saturated core;

specifically, the high-temperature high-pressure nuclear magnetic resonance experiment measuring device comprises a computer, a nuclear magnetic resonance measuring instrument, a magnet box with a non-magnetic core holder, a core sample, a confining pressure intermediate container, a confining pressure pump, a pore intermediate container, a pore pressure pump, a feedback control pressure pump and a measuring cylinder;

one side of the nuclear magnetic resonance measuring instrument is connected with a computer, and the other side of the nuclear magnetic resonance measuring instrument is connected with a non-magnetic core holder in the magnet box;

the non-magnetic core holder is internally provided with a core sample;

the two sides of the nonmagnetic core holder are respectively connected with a confining pressure intermediate container through confining pressure valves, and the confining pressure intermediate container is connected with a confining pressure pump;

the inlet end and the outlet end of the nonmagnetic core holder are respectively connected with a pore middle container through a pore pressure valve, and the pore middle container is connected with a pore pressure pump;

the outlet end of the nonmagnetic core holder is connected with a feedback pressure pump through a feedback pressure valve, and the feedback pressure valve is connected with a measuring cylinder;

the magnetic core holder, the confining pressure intermediate container and the confining pressure valve are connected through a metal nonmagnetic pipeline;

the confining pressure intermediate container is connected with a temperature controller;

the confining pressure intermediate container is filled with fluorine oil; the pore intermediate container is filled with brine or methane gas;

the confining pressure middle container comprises a No. 1 confining pressure middle container and a No. 2 confining pressure middle container, one end of the No. 1 confining pressure middle container is connected with a No. 1 confining pressure pump, the other end of the No. 1 confining pressure middle container is connected with a confining pressure cavity of the nonmagnetic core holder through a pipeline, one end of the No. 2 confining pressure middle container is connected with the No. 2 confining pressure pump, and the other end of the No. 2 confining pressure middle container is connected with a confining pressure cavity of the nonmagnetic core holder through a pipeline.

2. The method according to claim 1, wherein the pretreatment of the core sample in step S2 is: and (3) after washing oil and drying the core sample, vacuumizing and pressurizing saturated brine, and calculating the pore volume, the total volume and the porosity of the core sample according to the dry weight, the wet weight and the floating weight of the core sample.

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