CN115436411A - Experimental device and method for water injection salt dissolution rate after fracturing of interbalted shale - Google Patents
Experimental device and method for water injection salt dissolution rate after fracturing of interbalted shale Download PDFInfo
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Abstract
The invention discloses an experimental device and method for water injection salt dissolution rate after fracturing of inter-salt shale, comprising the following steps: the middle container comprises a stratum aqueous solution middle container, a low-salinity aqueous solution middle container and a saturated fluorine oil middle container; one end of the core holder is connected with the injection pump through the middle container, and the other end of the core holder is connected with a back pressure valve; the confining pressure loading system is connected with the rock core holder; the nuclear magnetic resonance testing system is connected with the rock core holder; the middle container comprises a stratum aqueous solution middle container and a low-salinity aqueous solution middle container, the experiment device splits the columnar rock core of the shale, combines the fractured rock core simulated by the glass tube, performs the low-salinity water injection salt dissolution experiment, obtains the salt dissolution rate through nuclear magnetic resonance scanning and calculation, and provides experiment and theoretical support for calculating the salt dissolution rate of the columnar rock core of the shale between salts.
Description
Technical Field
The invention belongs to the technical field of petroleum engineering, and particularly relates to an experimental device and method for water injection salt dissolution rate after fracturing of shale between salts.
Background
The domestic sunken salt shale oil in the Yangtze river is typical salt shale oil in China. The depression of the submerged river is not only rich in hydrocarbon source rocks, but also is the most main salt formation area, and a reservoir layer comprises two sets of salt rock layers. At present, with the development of hydraulic fracturing, waterflooding and huff and puff and the like, salt crystals (main components are Na2SO 4. CaSO 4) in a reservoir can be decomposed into Na2SO4 which is very soluble in water and CaSO4 which is slightly soluble in water under the condition of water dissolution, the salt crystals (such as CaSO 4) in water can be separated out after being gathered to a certain degree, partial pore space is increased finally due to the dynamic reaction, namely, the salt dissolution effect is generated, and the salt dissolution effect has important theoretical research value and significance for the effective development of the shale oil between salts.
Disclosure of Invention
The invention aims to provide an experimental device for water injection and salt dissolution rate after fracturing of shale between salts.
In order to achieve the above object, the present invention provides an experimental apparatus for water injection salt dissolution rate after fracturing of inter-salt shale, comprising:
The intermediate container comprises a formation aqueous solution intermediate container, a low-salinity aqueous solution intermediate container and a saturated fluorine oil intermediate container;
one end of the core holder is connected with the injection pump through the middle container, and the other end of the core holder is connected with a back pressure valve;
the confining pressure loading system is connected with the core holder;
the nuclear magnetic resonance test system is connected with the rock core holder and can perform nuclear magnetic resonance scanning on the columnar rock core in the rock core holder and obtain a nuclear magnetic T2 spectrogram of the columnar rock core.
Optionally, the split core holder further comprises a plurality of hollow glass tubes, the glass tubes are arranged in the core holder, and the glass tubes are arranged between the split two semi-cylindrical cores.
Optionally, the oil-water meter is further included, and is connected with the back-pressure valve.
Optionally, the core holder further comprises two pressure sensors, and the two pressure sensors are respectively located at two ends of the core holder.
Optionally, the core holder is connected with a vacuum pump, and a temperature control structure is arranged outside the core holder.
The invention also provides an experimental method for the water injection salt dissolution rate after fracturing of the interbalted shale, which utilizes the experimental device and comprises the following steps:
acquiring a first nuclear magnetic T2 spectrogram of the columnar rock core in a saturated fluorine oil state;
splitting a columnar rock core into two halves in the diameter direction, and arranging glass tubes between the two halves of the columnar rock core at equal intervals;
injecting a stratum aqueous solution into the rock core holder, and setting the pressure value of a back pressure valve;
acquiring a second nuclear magnetic T2 spectrogram of the columnar rock core after the injection pressure of the formation aqueous solution is stable;
injecting a low-salinity water solution into the rock core holder, and increasing injection pressure and confining pressure;
obtaining a third nuclear magnetic T2 spectrogram of the columnar rock core after the injection pressure of the low-salinity water solution is stable;
and calculating the water injection salt solubility after the fracturing of the shale between the salts according to the first nuclear magnetic T2 spectrogram, the second nuclear magnetic T2 spectrogram and the third nuclear magnetic T2 spectrogram.
Optionally, the acquiring a first nuclear magnetic T2 spectrum of the columnar core in a saturated fluorine oil state includes:
washing the columnar rock core with oil and weighing the dry weight;
after the vacuum is carried out for the first preset time, the saturated fluorine oil solution is pressurized, and the wet weight is weighed after the second preset time;
Performing nuclear magnetic resonance scanning and obtaining the first nuclear magnetic T2 spectrogram of the columnar rock core in the state of saturated fluorine oil to obtain the total signal amount S after the saturated fluorine oil o 。
Optionally, the obtaining a second nuclear magnetic T2 spectrogram of the columnar core after the injection pressure of the formation aqueous solution is stabilized includes:
slowly injecting the formation aqueous solution at a first speed until the right end of the holder produces liquid;
increasing the pressure of the back pressure valve, boosting the pressure to the formation pressure, and measuring the volume of produced water and produced oil at a production end;
after the injection pressure of the formation aqueous solution is stable, performing nuclear magnetic resonance scanning to obtain the second nuclear magnetic T2 spectrogram to obtain the total signal S when the imbibition reaches the equilibrium im 。
Optionally, the obtaining a third nuclear magnetic T2 spectrogram of the columnar core after the injection pressure of the low-salinity aqueous solution is stabilized includes:
slowly injecting a low-mineralization-degree water solution at a second speed, and synchronously increasing injection pressure and confining pressure;
and after the continuous injection is carried out for a third preset time, closing the injection end, and carrying out nuclear magnetic resonance scanning after the pressure is stable to obtain a third nuclear magnetic T2 spectrogram.
Optionally, the calculating the water-injection salt solubility after fracturing the shale between salts according to the first nuclear magnetic T2 spectrogram, the second nuclear magnetic T2 spectrogram and the third nuclear magnetic T2 spectrogram comprises:
The salt solubility was calculated using the following formula:
wherein S is im The total signal amount when the imbibition reaches equilibrium; s o The total signal amount is after the fluorine oil is saturated; s di The total amount of signal when the salt dissolution reaches the equilibrium; phi is the salt dissolution rate.
The invention provides an experimental device for water injection salt dissolution rate after fracturing of interbalted shale, which has the beneficial effects that:
the experiment device splits the columnar core of the shale, combines the core after the glass tube simulation fracturing, injects a low-mineralization water salt dissolution experiment, obtains the salt dissolution rate through nuclear magnetic resonance scanning and calculation, and provides experiment and theoretical support for calculating the salt dissolution rate of the columnar core of the shale.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
Fig. 1 shows a schematic structural diagram of an experimental apparatus for water injection salt dissolution rate after fracturing of intersalt shale according to embodiment 1 of the present invention.
Fig. 2 shows a schematic structural diagram of a glass tube of example 1 of an experimental apparatus for water injection salt solubility after fracturing of the intersalt shale according to example 1 of the present invention.
FIG. 3 shows a comparison of nuclear magnetic T2 spectrum changes of an experimental method of water injection salt solubility after fracturing of the intersalt shale according to example 2 of the present invention.
FIG. 4 shows a schematic diagram of an experimental method for water injection and salt solubility after fracturing of the shale between salts according to embodiment 2 of the present invention
Description of the reference numerals:
1. an infusion pump; 2. an intermediate container; 3. a core holder; 4. a nuclear magnetic resonance testing system; 5. a glass tube; 6. and a back pressure valve.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Example 1
FIG. 1 is a schematic structural diagram of an experimental apparatus for water injection salt dissolution rate after fracturing of intersalt shale according to example 1 of the present invention; fig. 2 shows a schematic structural diagram of a glass tube of example 1 of an experimental apparatus for water injection and salt solubility after fracturing of the interbalted shale according to example 1 of the present invention.
As shown in fig. 1-2, an experimental apparatus for water injection and salt solubility after fracturing of inter-salt shale includes:
the middle container 2 comprises a stratum aqueous solution middle container, a low-salinity aqueous solution middle container and a saturated fluorine oil middle container;
one end of the core holder 3 is connected with the injection pump 1 through the middle container 2, and the other end of the core holder is connected with a back pressure valve 6;
the confining pressure loading system is connected with the core holder;
and the nuclear magnetic resonance testing system 4 is connected with the rock core holder, and is used for performing nuclear magnetic resonance scanning on the columnar rock core in the rock core holder 3 and obtaining a nuclear magnetic T2 spectrogram of the columnar rock core.
The injection pump 1 is a high-precision injection pump, a formation aqueous solution, a low-salinity aqueous solution and saturated fluorine oil for experiments are stored in a formation aqueous solution intermediate container, a low-salinity aqueous solution intermediate container and a saturated fluorine oil intermediate container respectively, a core sample is held and fixed through a core holder 3, the core holder is enabled to simulate an underground pressure environment through a confining pressure loading system, a nuclear magnetic resonance test system 4 is used for surveying and mapping nuclear magnetic T2 spectrograms of the core sample under different environmental states, the karst-dissolving effect of the core sample is confirmed by comparing a first nuclear magnetic T2 spectrogram of the core under the saturated fluorine oil state, a second nuclear magnetic T2 spectrogram under the formation aqueous solution state and a third nuclear magnetic T2 spectrogram under the low-salinity water state, the salt solubility is obtained through calculation, and a new method is provided for representation of a micro-pore structure of a reservoir after shale water injection and fracturing.
In this embodiment, the core holder further comprises a plurality of hollow glass tubes 5, the glass tubes 5 are arranged in the core holder, and the glass tubes are arranged between the split two semi-cylindrical cores.
Specifically, the external diameter of glass pipe 5 is 0.2cm, and the internal diameter is 0.1cm, can adjust length according to the rock core, can unimpededly circulate liquid between the hole of glass pipe 5 and glass pipe 5, and the rock core is divided into two parts, supports two parts rock core through glass pipe 5, does not hinder the liquid flow between two parts rock core simultaneously, reaches the unlimited water conservancy diversion fracture's after the simulation fracturing effect.
In this embodiment, still include the profit counter, the profit counter is connected with back pressure valve 6.
Specifically, the oil-water meter is connected with the gas flowmeter, and the oil and water output during the experiment of the oil-water meter and the gas flowmeter is measured by the oil-water meter.
In this embodiment, two pressure sensors are further included, and the two pressure sensors are respectively located at two ends of the core holder 3.
Specifically, the pressure at two ends of the core holder 3 is monitored in real time through two pressure sensors, so that the actual pressure environment of the core underground can be conveniently simulated.
In this embodiment, the core holder 3 is connected with a vacuum pump, and a temperature control structure is arranged outside the core holder 3.
The vacuum in the rock core holder is conveniently extracted through the vacuum pump, and a vacuum environment can be fixed and simulated through one-time clamping without secondary clamping, so that the experiment procedure is simplified, the environment temperature of the rock core holder is controlled through the temperature control structure, the experiment requirements of different temperatures are simulated, and the rock core holder can be dried conveniently.
Further, the device comprises a controller, the controller is electrically connected with the nuclear magnetic resonance testing system, the injection pump, the pressure sensor, the confining pressure loading system and the temperature control structure, the controller comprises a display unit, a first nuclear magnetic T2 spectrogram of the rock core in a saturated fluorine oil state, a second nuclear magnetic T2 spectrogram in a stratum water solution state and a third nuclear magnetic T2 spectrogram in a low mineralization water state are displayed and compared through the display unit, the temperature and the environment pressure of the rock core holder are displayed at the same time, the influence of the environment temperature and the environment pressure on the litholysis rate is conveniently judged, the experiment is simpler and more convenient, and the data measurement and calculation is more real and reliable.
Taking the experiment for characterizing the pore structure of the shale after water injection fracturing as an example:
s1, weighing dry weight of the oil-washed rock core, vacuumizing for 36 hours, pressurizing saturated fluorine oil (dehydrogenated crude oil) for 36 hours, weighing wet weight, and performing nuclear magnetic resonance test to obtain a first nuclear magnetic T2 spectrogram in a saturated fluorine oil state;
S2, splitting the columnar rock core, uniformly placing the columnar rock core in the middle of the split rock core through a glass tube, and then fixing the columnar rock core and placing the columnar rock core into a rock core holder;
s3, opening the intermediate container, injecting a stratum aqueous solution into the rock core holder, slowly injecting the stratum aqueous solution at the speed of 0.005mL/min until liquid is produced at the right end of the holder, increasing the pressure of a back pressure valve, boosting the pressure to the stratum pressure, and measuring the volume of produced water and produced oil at a production end;
s4, after the injection pressure is stable, performing nuclear magnetic resonance scanning at intervals, observing the change condition of a nuclear magnetic T2 spectrogram, when the increase amplitude of the total signal quantity of the nuclear magnetic T2 spectrogram does not exceed 0.5%, balancing the seepage at the moment, recording a second nuclear magnetic resonance T2 spectrogram at the moment, and stopping injection;
s5, opening the injection pump again, slowly injecting the low-salinity water solution into the rock core holder at the speed of 0.05mL/min, synchronously increasing the injection pressure and the confining pressure, and closing the injection end after 12 hours of injection;
s6, after the pressure is stable, performing nuclear magnetic resonance scanning at intervals, observing the change condition of a nuclear magnetic T2 spectrogram, and recording a third nuclear magnetic resonance T2 spectrogram when the salt dissolution effect is balanced when the total signal reduction amplitude of the nuclear magnetic T2 spectrogram does not exceed 0.5%;
S7, after the experiment is finished, reducing the pressure, and taking out the rock core;
s8, calculating the karst rate according to a formula, wherein the formula is as follows:
wherein: s. the im The total signal amount when the imbibition reaches equilibrium; so is the total signal amount after the fluorine oil is saturated; sdi is the total amount of signal when salt solubilization reaches equilibrium; phi is the salt dissolution rate.
Example 2
FIG. 3 is a graph comparing the nuclear magnetic T2 spectrum change of an experimental method of water injection and salt solubility after fracturing of the interbed shale according to example 2 of the present invention; fig. 4 shows a schematic diagram of an experimental method of water injection salt solubility after fracturing of the intersalt shale according to example 2 of the present invention.
As shown in fig. 3, the present invention further provides an experimental method for water injection salt solubility after fracturing of an intersalt shale, which utilizes the experimental apparatus according to the above, including:
acquiring a first nuclear magnetic T2 spectrogram of the columnar rock core in a saturated fluorine oil state;
splitting the columnar rock core into two halves along the diameter direction, and arranging glass tubes between the two halves of the columnar rock core at equal intervals;
injecting a stratum water solution into the core holder, and setting the pressure value of a back pressure valve;
acquiring a second nuclear magnetic T2 spectrogram of the columnar rock core after the injection pressure of the formation aqueous solution is stable;
injecting a low-salinity water solution into the rock core holder, and increasing injection pressure and confining pressure;
Obtaining a third nuclear magnetic T2 spectrogram of the columnar rock core after the injection pressure of the low-salinity water solution is stable;
and calculating the water injection salt solubility after fracturing the shale between the salts according to the first nuclear magnetic T2 spectrogram, the second nuclear magnetic T2 spectrogram and the third nuclear magnetic T2 spectrogram.
Specifically, changes before, during and after water injection after fracturing of shale between salts are simulated through an experimental device, a first nuclear magnetic T2 spectrogram, a second nuclear magnetic T2 spectrogram and a third nuclear magnetic T2 spectrogram are obtained by matching with a magnetic nuclear resonance system, and the total signal quantity S when imbibition reaches balance is obtained according to the spectrograms im Total signal S after saturation with fluorine oil o Is the total amount S of signal at which the salt dissolution reaches equilibrium di And then obtaining the karst rate through calculation, and providing experimental and theoretical support for calculating the salt solubility rate of the columnar core of the shale between salts.
The method comprises the steps of cleaning impurities, removing pollution to a sample in the mining process, reversely reducing the underground state of a rock core, dividing the rock core into two parts, simulating a reservoir structure after water injection fracturing by means of a glass tube, simulating nuclear magnetic T2 spectrograms of the rock core sample in different environments, surveying and mapping the nuclear magnetic T2 spectrograms of the rock core sample in different environment states by a nuclear magnetic resonance testing system, confirming the karst effect of the rock core sample by comparing a first nuclear magnetic T2 spectrogram of the rock core in a saturated fluorine oil state, a second nuclear magnetic T2 spectrogram in a stratum water solution state and a third nuclear magnetic T2 spectrogram in a low-salinity water state, further calculating the salt solubility, and providing a new method for representing the micro-pore structure of the reservoir after water injection fracturing of shale.
In this embodiment, the obtaining of the first nuclear magnetic T2 spectrum of the columnar core in the saturated fluorine oil state includes:
washing the columnar rock core with oil and weighing the dry weight;
after the vacuum is carried out for the first preset time, the saturated fluorine oil solution is pressurized, and the wet weight is weighed after the second preset time;
performing nuclear magnetic resonance scanning and obtaining the first nuclear magnetic T2 spectrogram of the columnar rock core in the state of saturated fluorine oil to obtain the total signal amount S after the saturated fluorine oil o 。
Specifically, the first preset time is 36 hours, the second preset time is 36 hours, the specific duration or the injection rate can be adjusted according to an actual experimental device, and the actual weight parameters of the columnar rock core are confirmed by oil washing, dry weight and wet weight in a matched manner, so that the subsequent calculation and research are facilitated.
In this embodiment, the obtaining of the second nuclear magnetic T2 spectrum of the columnar core after the injection pressure of the formation aqueous solution is stabilized includes:
slowly injecting the formation aqueous solution at a first speed until the right end of the holder produces liquid;
increasing the pressure of the back pressure valve, boosting the pressure to the formation pressure, and measuring the volume of produced water and produced oil at a production end;
after the injection pressure of the formation aqueous solution is stable, performing nuclear magnetic resonance scanning to obtain a second nuclear magnetic T2 spectrogram to obtain the total signal S when the imbibition reaches the equilibrium im 。
Specifically, the first speed is 0.005mL/min, the formation aqueous solution is slowly injected at the speed of 0.005mL/min until the right end of the holder produces liquid, the pressure of the back pressure valve is increased to the formation pressure, and the volume of produced water and produced oil is measured at the production end;
after the injection pressure is stable, performing nuclear magnetic resonance scanning at intervals, observing the change condition of a second nuclear magnetic T2 spectrogram, when the increase amplitude of the total signal quantity of the second nuclear magnetic T2 spectrogram is not more than 0.5%, balancing the seepage at the moment, recording the second nuclear magnetic resonance T2 spectrogram at the moment, and stopping injection;
the formation aqueous solution is slowly injected at the speed of 0.005mL/min to ensure that the formation aqueous solution is stably and effectively injected, the pressure is increased to the formation pressure to simulate the real underground pressure by improving the pressure of a back pressure valve, the data authenticity is improved, the output rate is conveniently confirmed by measuring the oil and water output in the experiment through an oil-water meter, and the influence of the salt dissolution rate is confirmed.
In this embodiment, the obtaining of the third nuclear magnetic T2 spectrum of the columnar core after the injection pressure of the low-salinity aqueous solution is stabilized includes:
slowly injecting a low-salinity water solution at a second speed, and synchronously increasing injection pressure and confining pressure;
and after the continuous injection is carried out for a third preset time, closing the injection end, and carrying out nuclear magnetic resonance scanning after the pressure is stable to obtain a third nuclear magnetic T2 spectrogram.
Specifically, the second speed is 0.05mL/min, the third preset time is 12 hours, the injection pump is turned on again, the low-salinity aqueous solution is slowly injected into the core holder at the speed of 0.05mL/min, the injection pressure and the confining pressure are synchronously increased, and the injection end is closed after 12 hours of injection;
after the pressure is stable, performing nuclear magnetic resonance scanning at intervals, observing the change condition of a nuclear magnetic T2 spectrogram, and recording the nuclear magnetic T2 spectrogram when the salt dissolution effect is balanced when the reduction amplitude of the total signal quantity of the nuclear magnetic T2 spectrogram does not exceed 0.5%;
injecting water after simulating shale fracturing among underground salts, slowly injecting a low-salinity water solution at a speed of 0.05mL/min, synchronously increasing injection pressure and confining pressure to enable the low-salinity water to be fully contacted with a rock core, standing for 12 hours to enable the low-salinity water to be fully contacted with the rock core and to be closer to an underground real environment, and confirming the influence of salt solubility on oil yield through a third nuclear magnetic T2 spectrogram under a post-detection and drawing low-salinity water state.
In this embodiment, calculating the waterflood salt dissolution rate after fracturing the interbed shale according to the first nuclear magnetic T2 spectrum, the second nuclear magnetic T2 spectrum, and the third nuclear magnetic T2 spectrum includes:
the salt solubility was calculated using the following formula:
Wherein S is im The total signal amount when the imbibition reaches equilibrium; s o The total signal amount is after the fluorine oil is saturated; s di The total signal amount when the salt dissolution effect reaches the equilibrium; phi is the salt dissolution rate.
Specifically, the total signal amount of the first nuclear magnetic T2 spectrogram, the second nuclear magnetic T2 spectrogram and the third nuclear magnetic T2 spectrogram during surveying and mapping is reduced by not more than 0.5%, so that the stability of surveying and mapping data is guaranteed, the influence on data operation caused by extreme stirring when the data are unstable is avoided, and the practicability is reduced.
Taking the experiment for characterizing the pore structure of the shale after water injection fracturing as an example:
s1, weighing dry weight of the oil-washed rock core, vacuumizing for 36 hours, pressurizing saturated fluorine oil (dehydrogenated crude oil) for 36 hours, weighing wet weight, and performing nuclear magnetic resonance test to obtain a first nuclear magnetic T2 spectrogram in a saturated fluorine oil state;
s2, splitting the columnar rock core, uniformly placing the columnar rock core in the middle of the split rock core through a glass tube, and then fixing the columnar rock core and placing the columnar rock core into a rock core holder;
s3, opening the intermediate container, injecting a stratum aqueous solution into the rock core holder, slowly injecting the stratum aqueous solution at the speed of 0.005mL/min until liquid is produced at the right end of the holder, increasing the pressure of a back pressure valve, boosting the pressure to the stratum pressure, and measuring the volume of produced water and produced oil at a production end;
S4, after the injection pressure is stable, performing nuclear magnetic resonance scanning at intervals, observing the change condition of a nuclear magnetic T2 spectrogram, when the increase amplitude of the total signal quantity of the nuclear magnetic T2 spectrogram does not exceed 0.5%, balancing the seepage at the moment, recording a second nuclear magnetic resonance T2 spectrogram at the moment, and stopping injection;
s5, opening the injection pump again, slowly injecting the low-salinity water solution into the core holder at the speed of 0.05mL/min, synchronously increasing the injection pressure and the confining pressure, and closing the injection end after 12 hours of injection;
s6, after the pressure is stable, performing nuclear magnetic resonance scanning at intervals, observing the change condition of a nuclear magnetic T2 spectrogram, and recording a third nuclear magnetic resonance T2 spectrogram when the salt dissolution effect is balanced when the reduction amplitude of the total signal quantity of the nuclear magnetic T2 spectrogram does not exceed 0.5%;
s7, after the experiment is finished, reducing the pressure, and taking out the rock core;
s8, calculating the karst rate according to a formula, wherein the formula is as follows:
wherein: s im The total signal amount when the imbibition reaches equilibrium; so is the total signal amount after the fluorine oil is saturated; sdi is the total amount of signal when salt solubilization reaches equilibrium; phi is the salt dissolution rate.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (10)
1. The utility model provides an experimental apparatus of water injection salt dissolution rate after shale fracturing between salt which characterized in that includes:
the intermediate container comprises a formation aqueous solution intermediate container, a low-salinity aqueous solution intermediate container and a saturated fluorine oil intermediate container;
one end of the core holder is connected with the injection pump through the middle container, and the other end of the core holder is connected with a back pressure valve;
the confining pressure loading system is connected with the core holder;
the nuclear magnetic resonance testing system is connected with the rock core holder and can perform nuclear magnetic resonance scanning on the columnar rock core in the rock core holder and obtain a nuclear magnetic T2 spectrogram of the rock core.
2. The experimental device for the water injection salt dissolution rate after fracturing of the interbed shale as claimed in claim 1, further comprising a plurality of hollow glass tubes, wherein the glass tubes are arranged in the core holder and are used for being arranged in the middle of the split semi-cylindrical cores.
3. The experimental device for the water injection salt dissolution rate after fracturing of the intersalt shale as claimed in claim 1, further comprising an oil-water meter, wherein the oil-water meter is connected with the back pressure valve.
4. The experimental device for the water injection salt dissolution rate after fracturing of the interbed shale as claimed in claim 1, further comprising two pressure sensors, wherein the two pressure sensors are respectively located at two ends of the core holder.
5. The experimental device for the water injection salt dissolution rate after fracturing of the interbalted shale as claimed in claim 4, wherein the core holder is connected with a vacuum pump, and a temperature control structure is arranged outside the core holder.
6. An experimental method for the water injection and salt dissolution rate after the fracturing of the shale between salts, which utilizes the experimental device according to any one of claims 1 to 5, is characterized by comprising the following steps:
acquiring a first nuclear magnetic T2 spectrogram of the columnar rock core in a saturated fluorine oil state;
splitting a columnar rock core into two halves in the diameter direction, and arranging glass tubes between the two halves of the columnar rock core at equal intervals;
injecting a stratum aqueous solution into the rock core holder, and setting the pressure value of a back pressure valve;
acquiring a second nuclear magnetic T2 spectrogram of the columnar rock core after the injection pressure of the formation water solution is stable;
injecting a low-salinity water solution into the core holder, and increasing injection pressure and confining pressure;
obtaining a third nuclear magnetic T2 spectrogram of the columnar rock core after the injection pressure of the low-salinity water solution is stable;
And calculating the water injection salt solubility after the fracturing of the shale between the salts according to the first nuclear magnetic T2 spectrogram, the second nuclear magnetic T2 spectrogram and the third nuclear magnetic T2 spectrogram.
7. The method for testing the water injection and salt solubility after fracturing the shale between salts according to claim 6, wherein the obtaining of the first nuclear magnetic T2 spectrogram of the columnar core in the saturated fluorine oil state comprises:
washing the columnar rock core with oil and weighing the dry weight;
after the vacuum is carried out for the first preset time, the saturated fluorine oil solution is pressurized, and the wet weight is weighed after the second preset time;
and performing nuclear magnetic resonance scanning and obtaining the first nuclear magnetic T2 spectrogram of the columnar rock core in the saturated fluorine oil state to obtain the total signal So after the saturated fluorine oil.
8. The method as claimed in claim 6, wherein the obtaining of the second nuclear magnetic T2 spectrum of the columnar core after the injection pressure of the aqueous formation solution is stabilized includes:
slowly injecting the formation aqueous solution at a first speed until the right end of the holder produces liquid;
increasing the pressure of the back pressure valve, boosting the pressure to the formation pressure, and measuring the volume of produced water and produced oil at a production end;
after the injection pressure of the formation aqueous solution is stable, performing nuclear magnetic resonance scanning to obtain the second nuclear magnetic T2 spectrogram to obtain the total signal S when the imbibition reaches the equilibrium im 。
9. The method as claimed in claim 6, wherein the obtaining of the third nuclear magnetic T2 spectrum of the columnar core after the injection pressure of the low salinity water solution is stabilized includes:
slowly injecting the low-salinity water solution at a second speed, and synchronously increasing the injection pressure and the confining pressure;
and after the continuous injection is carried out for a third preset time, closing the injection end, and carrying out nuclear magnetic resonance scanning after the pressure is stable to obtain a third nuclear magnetic T2 spectrogram.
10. The method for testing the water injection salt solubility after fracturing the shale between salts according to claim 6, wherein the calculating the water injection salt solubility after fracturing the shale between salts according to the first nuclear magnetic T2 spectrogram, the second nuclear magnetic T2 spectrogram and the third nuclear magnetic T2 spectrogram comprises:
the salt solubility was calculated using the following formula:
wherein S is im The total signal amount when the imbibition reaches equilibrium; s o The total signal amount is after the fluorine oil is saturated; s di The total signal amount when the salt dissolution effect reaches the equilibrium; phi is the salt dissolution rate.
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| CN116242873A (en) * | 2023-05-11 | 2023-06-09 | 长江三峡集团实业发展(北京)有限公司 | Dry-hot rock heat collection visual testing device and testing method |
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| CN116242873A (en) * | 2023-05-11 | 2023-06-09 | 长江三峡集团实业发展(北京)有限公司 | Dry-hot rock heat collection visual testing device and testing method |
| CN116242873B (en) * | 2023-05-11 | 2023-08-18 | 长江三峡集团实业发展(北京)有限公司 | Dry-hot rock heat collection visual testing device and testing method |
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