CN109827882B - Shale rock adsorption and desorption experimental device - Google Patents
Shale rock adsorption and desorption experimental device Download PDFInfo
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Abstract
The application provides a shale rock adsorbs desorption experimental apparatus, takes place system, adsorption and desorption system, back pressure system, constant temperature system and data acquisition system including air supply system, ultrasonic wave, can provide gas for adsorbing the desorption system through the air supply system, makes the rock sample among the adsorption and desorption system adsorb experiment and desorption experiment to utilize the back pressure system to carry out pressure control for adsorbing the desorption system. In addition, the ultrasonic wave generating system carries out ultrasonic excitation on the rock sample by sending out an ultrasonic signal, and the data acquisition system is used for acquiring the experimental data of the rock sample in the adsorption experiment and the desorption experiment and carrying out analysis processing to obtain the adsorption experiment result and the desorption experiment of the rock sample under different experimental conditions. Therefore, the influence of ultrasonic excitation on adsorption and desorption experiments of shale rock samples can be analyzed, a theoretical basis is provided for shale gas exploitation, and the shale gas well exploitation efficiency is improved.
Description
Technical Field
The invention relates to the technical field of geological exploration rock experiments, in particular to a shale rock adsorption and desorption experiment device.
Background
The shale gas occurrence form is different from the conventional oil and gas reservoir and comprises a free state, an adsorption state, a dissolution state and the like, and in the original state, the gas in the shale is in a dynamic equilibrium state of the adsorption state and the free state. Free gas in shale is mainly stored in micro cracks and organic matters or pores among mineral particles in a shale reservoir, and adsorbed gas is mainly attached to the surfaces of the mineral particles and the organic matters in the shale. Meanwhile, the existing shale gas reservoir exploitation experience shows that the shale gas well is high in yield at the exploitation initial stage, but the decline is fast. The gas well production declines slowly in the later stages, mainly due to desorption of adsorbed gas from the shale. The desorption of shale gas is mainly that when a shale gas reservoir is developed, the dynamic balance relation between the gas in an adsorption state and a free state is broken, and the adsorbed gas leaves the surfaces of mineral particles and organic matters in the shale to be changed into free gas. In the process of exploiting the shale gas reservoir, free gas and desorbed gas enter a fracture system through diffusion to cause pressure reduction, adsorbed gas in shale is gradually desorbed and enters fractures, and the yield of a shale gas well is gradually reduced. This demonstrates that promoting desorption of adsorbed gas in a shale gas reservoir has a significant impact on the development of shale gas reservoirs.
At present, shale gas exploitation is mainly realized by adopting a pressure reduction desorption mode, but the single pressure reduction desorption exploitation mode has the defects of long period, incapability of continuously increasing the yield and the like, so that the exploitation effect of the shale gas reservoir is not ideal.
Disclosure of Invention
In view of this, the present application aims to provide an experimental apparatus for shale rock adsorption and desorption to improve the above problems.
The embodiment of the application provides a shale rock adsorption and desorption experimental device which comprises an air source system, an ultrasonic generation system, an adsorption and desorption system, a back pressure system, a constant temperature system and a data acquisition system;
the gas source system is connected with one end of the adsorption and desorption system and is used for injecting gas into the adsorption and desorption system;
the adsorption and desorption system is used for accommodating a rock sample and enabling the rock sample to carry out gas adsorption experiments and desorption experiments in the adsorption and desorption system;
the back pressure system is connected with the other end of the adsorption and desorption system and is used for setting the pressure of the adsorption and desorption system so as to enable the pressure of the adsorption and desorption system to reach the set pressure required by the desorption experiment;
the ultrasonic generation system is connected with the adsorption and desorption system and is used for sending an ultrasonic signal to carry out ultrasonic excitation on the rock sample;
the constant temperature system is used for providing a constant set temperature environment for the adsorption and desorption system;
the data acquisition system is connected with the adsorption and desorption system and the back pressure system and is used for acquiring the experimental data of the rock sample in the adsorption experiment and the desorption experiment, and analyzing and processing the experimental data to obtain the adsorption experiment result and the desorption experiment result of the rock sample under different experimental conditions.
Optionally, the adsorption desorption system comprises a sample chamber, a first intermediate vessel, an evacuation pump, a first pressure sensor, a second pressure sensor, and a first displacement pump;
the first intermediate container is arranged between the gas source system and the inlet end of the sample chamber and is used for storing gas filled by the gas source system and delivering the gas to the sample chamber;
the evacuation pump is connected with the sample chamber and is used for carrying out vacuum-pumping treatment on the sample chamber;
the first pressure sensor is arranged at the inlet end of the sample chamber, the second pressure sensor is arranged at the outlet end of the sample chamber, and the first pressure sensor and the second pressure sensor are respectively used for detecting pressure data of the inlet end and the outlet end of the sample chamber;
the first displacement pump is connected to the first intermediate reservoir for providing a pressure source to the first intermediate reservoir, adjusting a pressure value of the first intermediate reservoir, and measuring a free space volume of the sample chamber.
Optionally, the data acquisition system includes a main control device, and a data signal collector and a gas flow meter connected to the main control device;
the data signal collector is connected with the first pressure sensor and the second pressure sensor, and is used for obtaining pressure data collected by the first pressure sensor and the second pressure sensor and sending the pressure data to the main control equipment;
the gas flowmeter is connected with the back pressure system and used for collecting the gas flow of the rock sample at the back pressure system after the desorption experiment and sending the gas flow to the main control equipment;
and the master control equipment processes and stores the received pressure data and the received gas flow.
Optionally, the main control device is further configured to obtain readings of the first displacement pump at each equilibrium pressure point in an adsorption experiment, where the adsorption experiment result includes an adsorption gas amount at each equilibrium pressure point, where the adsorption gas amount at each equilibrium pressure point is calculated by the main control device according to the readings, the equilibrium pressure, and the temperature value of the first displacement pump at each equilibrium pressure point, and according to the following formula:
wherein n isiThe adsorption gas amount of the ith equilibrium pressure point; m is the mass of the rock sample particles in the sample chamber; p is a radical ofiIs the ith equilibrium pressure; viThe volume of the pump is fed into the ith balance pressure point; ziIs the gas compression factor at the ith equilibrium pressure; p is a radical ofi-1Is the i-1 th equilibrium pressure; zi-1Is the gas compression factor at the i-1 th equilibrium pressure; r is a molar gasCounting; t is the experimental temperature; vfreeIs the free space volume of the sample chamber.
Optionally, the desorption experiment data includes desorption gas amounts at each desorption equilibrium pressure point, where the desorption gas amount at each desorption equilibrium pressure point is calculated by the main control device according to a gas flow, a desorption equilibrium pressure, and a temperature value collected by the gas flowmeter at each desorption equilibrium pressure point according to the following formula:
wherein, n'iThe desorption gas amount is the ith desorption equilibrium pressure point; p'iIs the ith desorption equilibrium pressure; v'iDesorbing the gas volume in a standard state at the ith desorption equilibrium pressure point; z'iIs the gas compression factor at the ith desorption equilibrium pressure; p'i-1Is the i-1 th desorption equilibrium pressure; z'i-1The gas compression factor is the gas compression factor under the i-1 st desorption equilibrium pressure; p is a radical ofscAtmospheric pressure in a standard state; t isscIs the temperature at the standard state; zscIs a gas compression factor under a standard state; vfreeIs the free space volume of the sample chamber; r is a molar gas constant; t is the experimental temperature.
Optionally, the ultrasonic generating system comprises an ultrasonic generator and an ultrasonic transducer connected with the ultrasonic generator;
the ultrasonic generator is used for sending a specific frequency signal to drive the ultrasonic transducer to work;
the ultrasonic transducer is used for emitting ultrasonic signals with corresponding frequencies under the driving of the ultrasonic generator.
Optionally, the air source system comprises a high-pressure air cylinder, a booster pump, an air compressor and a first valve;
the high-pressure gas cylinder is connected with one end of the booster pump and is used for providing high-pressure gas;
the booster pump is also connected with an air compressor and an adsorption and desorption system and is used for boosting the gas in the adsorption and desorption system;
the first valve is arranged between the booster pump and the high-pressure gas cylinder.
Optionally, the back pressure system comprises a second intermediate container, a second displacement pump, a second vent valve, and a back pressure valve;
the inlet of the back pressure valve is connected with the outlet end of the adsorption and desorption system, and the outlet of the back pressure valve is connected with the data acquisition system;
the second intermediate container is connected with the back pressure valve, and the pressure of the back pressure valve is controlled and adjusted by taking gas in the second intermediate container as a pressure transmission medium;
the second displacement pump is connected to one end, far away from the back pressure valve, of the second intermediate container and is used for adjusting the pressure of the second intermediate container;
the second vent valve is connected to the back pressure valve for regulating the pressure of the back pressure valve.
Optionally, a holder is further arranged in the sample chamber and used for placing a rock sample;
the shale rock adsorption and desorption experimental device further comprises a hand-operated pump connected with the holder and used for pressurizing the holder.
Optionally, the constant temperature system comprises a constant temperature box for accommodating the adsorption and desorption system, and a temperature sensor and a temperature controller connected with the temperature sensor are arranged in the constant temperature box;
the temperature sensor is used for collecting a temperature value in the constant temperature box and sending the temperature value to the temperature controller;
the temperature controller is used for controlling the temperature in the constant temperature box according to the received temperature value.
The shale rock adsorption and desorption experimental apparatus provided by the embodiment of the application comprises an air source system, an ultrasonic generation system, an adsorption and desorption system, a back pressure system, a constant temperature system and a data acquisition system, wherein gas can be provided for the adsorption and desorption system through the air source system, so that a rock sample in the adsorption and desorption system is subjected to adsorption experiment and desorption experiment, and the back pressure system is utilized for carrying out pressure control on the adsorption and desorption system. In addition, the ultrasonic wave generating system carries out ultrasonic excitation on the rock sample by sending out an ultrasonic signal, and the data acquisition system is used for acquiring the experimental data of the rock sample in the adsorption experiment and the desorption experiment and carrying out analysis processing to obtain the adsorption experiment result and the desorption experiment of the rock sample under different experimental conditions. Therefore, the influence of ultrasonic excitation on adsorption and desorption experiments of shale rock samples can be analyzed, a theoretical basis is provided for shale gas exploitation, and the shale gas well exploitation efficiency is improved.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic structural block diagram of an experimental apparatus for adsorbing and desorbing shale rock provided in an embodiment of the present application.
Fig. 2 is one of the structure diagrams of an experimental apparatus for adsorbing and desorbing shale rock provided in an embodiment of the present application.
Fig. 3 is a second structure diagram of an experimental apparatus for adsorbing and desorbing shale rock provided in an embodiment of the present application.
Fig. 4 is a schematic structural block diagram of a constant temperature system provided in an embodiment of the present application.
Fig. 5 is a schematic diagram of the relationship between the adsorbed gas and the equilibrium pressure provided in the embodiment of the present application.
Fig. 6 is a schematic diagram of the relationship between the desorption equilibrium time and the equilibrium pressure provided in the embodiment of the present application.
Fig. 7 is a graph illustrating a relationship between a desorption equilibrium time reduction rate and an equilibrium pressure according to an embodiment of the present application.
Icon: 10-a gas source system; 11-a high-pressure gas cylinder; 12-a booster pump; 13-an air compressor; 14-a first valve; 20-an ultrasonic generating system; 21-an ultrasonic generator; 22-ultrasonic transducer; 30-adsorption desorption system; 31-a sample chamber; 32-a first intermediate container; 33-a pump for evacuation; 34-a first pressure sensor; 35-a second pressure sensor; 36-a first displacement pump; 37-hand pump; 38-a first upper valve; 39-a first lower end valve; 310-an inlet valve; 311-an outlet valve; 312-a first vent valve; 40-a back pressure system; 41-a second intermediate container; 42-a second displacement pump; 43-a second vent valve; 44-back pressure valve; 45-a second upper valve; 46-a second lower end valve; 50-a constant temperature system; 51-a constant temperature box; 52-temperature sensor; 53-temperature controller; 60-a data acquisition system; 61-a master control device; 62-a data signal collector; 63-gas flow meter.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
Referring to fig. 1, an example of the present application provides an adsorption and desorption experiment apparatus for shale rock, which includes an air source system 10, an ultrasonic wave generation system 20, an adsorption and desorption system 30, a back pressure system 40, a constant temperature system 50, and a data acquisition system 60.
The gas source system 10 is connected to one end of the adsorption and desorption system 30, and is used for injecting gas into the adsorption and desorption system 30.
The adsorption and desorption system 30 is used for accommodating a rock sample, so that the rock sample can be subjected to an adsorption experiment and a desorption experiment of gas in the adsorption and desorption system 30.
The back pressure system 40 is connected to the other end of the adsorption and desorption system 30, and is configured to set the pressure of the adsorption and desorption system 30, so that the pressure of the adsorption and desorption system 30 reaches the set pressure required by the desorption experiment.
The ultrasonic generation system 20 is connected to the adsorption and desorption system 30, and is configured to send an ultrasonic signal to perform ultrasonic excitation on the rock sample.
The constant temperature system 50 is used to provide a constant set temperature environment for the adsorption and desorption system 30.
The data acquisition system 60 is connected to the adsorption and desorption system 30 and the back pressure system 40, and is configured to acquire experimental data of the rock sample in an adsorption experiment and a desorption experiment, and analyze and process the experimental data to obtain an adsorption experiment result and a desorption experiment result of the rock sample under different experiment conditions.
Based on the device, the analysis of the obtained experimental data under different experimental conditions, such as under the ultrasonic excitation condition, under the ultrasonic excitation-free condition, under different ultrasonic wave action time, under different ultrasonic frequencies and the like, can be realized, so that the influence of different experimental conditions on the adsorption and desorption experiment of the rock sample is obtained, and a scientific basis is provided for shale gas exploitation.
Referring to fig. 2, in the present embodiment, the air source system 10 includes a high pressure gas cylinder 11, a booster pump 12, an air compressor 13 and a first valve 14.
The high-pressure gas cylinder 11 is connected with one end of the booster pump 12 and is used for providing high-pressure gas. The booster pump 12 is also connected with an air compressor 13 and an adsorption and desorption system 30, and is used for boosting the gas in the adsorption and desorption system 30. The first valve 14 is provided between the booster pump 12 and the high-pressure gas cylinder 11.
Optionally, in the present embodiment, the adsorption and desorption system 30 includes a sample chamber 31, a first intermediate container 32, a evacuation pump 33, a first pressure sensor 34, a second pressure sensor 35, and a first displacement pump 36.
The first intermediate container 32 is disposed between the gas source system 10 and the inlet end of the sample chamber 31 for storing the gas filled by the gas source system 10 and delivering the gas to the sample chamber 31. The evacuation pump 33 is connected to the sample chamber 31, and is configured to evacuate the sample chamber 31.
The first pressure sensor 34 is disposed at the inlet end of the sample chamber 31, the second pressure sensor 35 is disposed at the outlet end of the sample chamber 31, and the first pressure sensor 34 and the second pressure sensor 35 are respectively used for detecting pressure data at the inlet end and the outlet end of the sample chamber 31.
As an embodiment, the sample chamber 31 may have a cylindrical cavity inside, for example, a cylindrical cavity with a diameter of 100mm × 100mm, and a rock sample may be placed in the cylindrical cavity.
As another embodiment, referring to fig. 3, a holder may be disposed in the sample chamber 31, and a rock sample may be placed by the holder. The shale rock adsorption and desorption experimental device further comprises a hand-operated pump 37 connected with the holder and used for pressurizing the holder.
The first displacement pump 36 is connected to the first intermediate reservoir 32 for providing a pressure source for the first intermediate reservoir 32, for adjusting the pressure value of the first intermediate reservoir 32, and also for measuring the free space volume of the sample chamber 31.
The adsorption and desorption system 30 further includes a first upper valve 38, a first lower valve 39, an inlet valve 310, an outlet valve 311, and a first vent valve 312.
The first lower end valve 39 is provided at an end of the first intermediate tank 32 close to the first displacement pump 36, and the first upper end valve 38 is provided at an end of the first intermediate tank 32 opposite to the first lower end valve 39.
The inlet valve 310 is disposed at an inlet end of the sample chamber 31, and the outlet valve 311 is disposed at an outlet end of the sample chamber 31. The first vent valve 312 is disposed between the first upper valve 38 and the inlet valve 310.
Referring to fig. 4, in the present embodiment, the constant temperature system 50 includes a constant temperature box 51 for accommodating the adsorption and desorption system 30, wherein the sample chamber 31 and the first intermediate container 32 may be partially located in the constant temperature box 51.
A temperature sensor 52 and a temperature controller 53 connected to the temperature sensor 52 are provided in the oven 51. The temperature sensor 52 is configured to collect a temperature value in the thermostat 51, and send the temperature value to the temperature controller 53. The temperature controller 53 is configured to control the temperature inside the oven 51 according to the received temperature value.
Referring again to fig. 2, the ultrasonic generating system 20 includes an ultrasonic generator 21 and an ultrasonic transducer 22 connected to the ultrasonic generator 21. The ultrasonic generator 21 is used for emitting a signal with a specific frequency to drive the ultrasonic transducer 22 to work. The ultrasonic transducer 22 is used for emitting an ultrasonic signal with a corresponding frequency under the driving of the ultrasonic generator 21. Wherein, the ultrasonic transducer 22 is embedded at the inlet end of the sample chamber 31.
In this embodiment, the back pressure system 40 includes a second intermediate container 41, a second displacement pump 42, a second relief valve 43, and a back pressure valve 44.
The inlet of the back pressure valve 44 is connected to the outlet of the adsorption and desorption system 30, and the outlet of the back pressure valve 44 is connected to the data acquisition system 60. The second intermediate container 41 is connected to the back pressure valve 44, and the pressure of the back pressure valve 44 is controlled and adjusted by using the gas in the second intermediate container 41 as a pressure transmission medium. The second displacement pump 42 is connected to the end of the second intermediate reservoir 41 remote from the back pressure valve 44 for regulating the pressure of the second intermediate reservoir 41. The second vent valve 43 is connected to the back pressure valve 44 for regulating the pressure of the back pressure valve 44.
Optionally, the back pressure system 40 further includes a second upper valve 45 and a second lower valve 46, the second lower valve 46 is disposed at an end of the second intermediate container 41 close to the second displacement pump 42, and the second upper valve 45 is disposed at an end of the second intermediate container 41 opposite to the second lower valve 46.
The data acquisition system 60 comprises a main control device 61, and a data signal collector 62 and a gas flow meter 63 which are connected with the main control device 61.
The data signal collector 62 is connected to the first pressure sensor 34 and the second pressure sensor 35, and is configured to obtain pressure data collected by the first pressure sensor 34 and the second pressure sensor 35, and send the pressure data to the main control device 61. The gas flowmeter 63 is connected with the back pressure system 40, and is used for collecting the gas flow of the rock sample at the back pressure system 40 after the desorption experiment, and sending the gas flow to the main control device 61. The main control device 61 processes and stores the received pressure data and gas flow.
Specifically, the main control device 61 may analyze experimental data obtained under the condition of ultrasonic excitation and analyze experimental data obtained under the condition of no ultrasonic excitation respectively, so as to obtain the influence of ultrasonic excitation on the adsorption and desorption experiment of the rock sample.
Optionally, the main control device 61 is further configured to obtain a reading, an equilibrium pressure, and a temperature value of the first displacement pump 36 at each equilibrium pressure point in an adsorption experiment, where the adsorption experiment result includes an adsorption gas amount at each equilibrium pressure point, where the adsorption gas amount at each equilibrium pressure point is calculated by the main control device 61 according to the reading, the equilibrium pressure, and the temperature value of the first displacement pump 36 at each equilibrium pressure point according to the following formula:
wherein n isiThe adsorption gas amount of the ith equilibrium pressure point; m is the mass of the rock sample particles in the sample chamber 31; p is a radical ofiThe ith equilibrium pressure; viPump volume (obtained from readings of the first displacement pump 36) for the ith equilibrium pressure point; ziIs the gas compression factor at the ith equilibrium pressure; p is a radical ofi-1The i-1 th equilibrium pressure; zi-1Is the gas compression factor at the i-1 th equilibrium pressure; r is a molar gas constant; t is the experimental temperature; vfreeIs the free space volume of the sample chamber 31.
In addition, the desorption experiment data includes desorption gas amounts at each desorption equilibrium pressure point, where the desorption gas amount at each desorption equilibrium pressure point is calculated by the main control device 61 according to the gas flow, the desorption equilibrium pressure, and the temperature value collected by the gas flowmeter 63 at each desorption equilibrium pressure point according to the following formula:
wherein, n'iThe desorption gas amount is the ith desorption equilibrium pressure point; p'iThe ith desorption equilibrium pressure; v'iDesorbing the gas volume (obtained according to the gas flow collected by the gas flowmeter 63) in a standard state at the ith desorption equilibrium pressure point; z'iIs the gas compression factor at the ith desorption equilibrium pressure; p'i-1The i-1 th desorption equilibrium pressure; z'i-1The gas compression factor is the gas compression factor under the i-1 st desorption equilibrium pressure; p is a radical ofscAtmospheric pressure in a standard state; t isscIs the temperature at the standard state; zscIs a gas compression factor under a standard state; vfreeIs the free space volume of the sample chamber 31.
The above formula can be adapted to the calculation of experimental data under the condition of ultrasonic excitation and the calculation of experimental data under the condition of no ultrasonic excitation.
In particular, a downhole rock sample rich in organic shale in a research work area can be collected, and the rock sample is dried for a period of time, such as 24 hours, at a set temperature, such as 60 ℃. The rock sample is then sampled according to industry standards to produce a 60-80 mesh sample of about 300g particles, wherein the diameter of the sample of particles may be between 0.18-0.25 mm. The rock sample is placed in the sample chamber 31 and the incubator 51 is set to an experimental temperature value, for example 60 ℃, wherein the temperature variation range of the incubator 51 should be less than or equal to 1 ℃.
First, the outlet valve 311 of the sample chamber 31 may be closed, and the sample chamber 31 may be vacuumized by the evacuation pump 33, and after a certain period of time, for example, 24 hours, the inlet valve 310 of the sample chamber 31 may be closed. The gas in the high-pressure gas cylinder 11, such as helium, is transferred into the first intermediate container 32, and the pressure value of the first intermediate container 32 is adjusted by the first displacement pump 36. After a period of settling time, the first upper valve 38 and the first vent valve 312 are opened, and after the air in the pipeline is exhausted, the first vent valve 312 is closed. After stabilization, an initial volume reading of first displacement pump 36 is recorded, and inlet valve 310 is opened to allow the slow injection of high pressure gas into sample chamber 31. When the values of the first and second pressure sensors 34, 35 at the inlet and outlet ends of the sample chamber 31 are consistent and stable, a volume reading of the first displacement pump 36 is taken. The difference between the initial volume reading of first displacement pump 36 and the volume readings of first pressure sensor 34 and second pressure sensor 35 when the values are consistent is the measured free space volume of sample chamber 31, and the calculation formula is shown as follows:
Vfree＝Va-Vb
wherein, VaIs an initial volume reading, V, of the first displacement pump 36bIs a volume reading of the first displacement pump 36 when the values of the first pressure sensor 34 and the second pressure sensor 35 are consistent. Wherein in the process ofFree space volume V of the line samplefreeThe measurement can be repeated twice, so that the accuracy of the measured free space volume can be ensured.
After the free space volume of the sample chamber 31 is measured, the above-described evacuation of the sample chamber 31 is repeated. The high purity methane is then transferred to the first intermediate vessel 32 using the high pressure gas cylinder 11. The pressure of the first intermediate container 32 is adjusted by the first displacement pump 36 to the set adsorption experimental pressure. After a period of settling time, the first upper valve 38 and the first vent valve 312 are opened, and after the air in the pipeline is exhausted, the first vent valve 312 is closed. After stabilization, the initial volume of the first displacement pump 36 is recorded and the inlet valve 310 is slowly opened to allow the gas to be slowly injected into the sample chamber 31, requiring an equilibration time of 6 hours for sufficient diffusion and adsorption of the gas. Until the values of the first pressure sensor 34 and the second pressure sensor 35 at the inlet end and the outlet end are consistent, and the volume of the first displacement pump 36 is not changed any more, the inlet valve 310 is closed, at this time, the difference between the experimental equilibrium pressure and the volume of the first displacement pump 36 or the volume of the pump entering (which is the adsorbed gas amount of the rock sample in the adsorption and desorption system 30 at the equilibrium pressure point) is recorded according to the stability of the whole adsorption and desorption system 30.
Meanwhile, the pressure changes of the first pressure sensor 34 and the second pressure sensor 35 at the inlet and the outlet are detected by the data signal collector 62, and the pressure is recorded, and the collected data can record data points every 30s and is stored in the storage module of the main control device 61. And repeating the process until the experiment set pressure and the adsorption process of the rock sample is finished. It is to be noted that, in the case of stepwise pressurization of the gas in the first intermediate tank 32, when the experimental pressure is greater than >10MPa, it is necessary to pressurize the gas in the first intermediate tank 32 to the set pressure using the air compressor 13 and the booster pump 12.
When the experimental pressure reaches the experimental set pressure, the inlet valve 310 is closed. The pressure value of the second displacement pump 42 is set, and the pressure of the back pressure valve 44 is adjusted so that the pressure of the back pressure valve 44 is gradually reduced to the set desorption experimental pressure. After a period of stabilization, the outlet valve 311 is opened, and the gas flow meter 63 collects the flow rate of the exhaust gas in the adsorption and desorption system 30 and transmits the flow rate to the main control device 61. The master control device 61 automatically records the instantaneous gas volume and the accumulated gas volume of the gas flow meter 63 for each desorption equilibrium pressure phase. The data points are recorded every 30s and stored in the storage module of the main control device 61. Meanwhile, when the values of the first pressure sensor 34 and the second pressure sensor 35 at the inlet and the outlet are consistent, the desorption time until the end of the desorption experiment pressure is recorded. And repeating the process until the pressure is set in the experiment and the desorption process of the rock sample is finished.
Through the steps, the adsorption and desorption experiments under the condition without ultrasonic excitation are completed. Hereinafter, the experimental procedure with the ultrasonic excitation condition will be briefly described.
Repeating the gas adsorption experiment, performing a gas desorption experiment of the rock sample under ultrasonic excitation on the basis, enabling the ultrasonic transducer 22 to perform ultrasonic excitation for a certain time at each desorption pressure point by utilizing the ultrasonic generator 21 with a certain power, then performing the desorption experiment, wherein the desorption process is consistent with the desorption experiment process, and recording pressure values at the inlet end and the outlet end, instantaneous gas amount, accumulated gas amount and desorption balance time. In addition, desorption experiments of excitation conditions such as different action time, ultrasonic frequency, power, vibration mode and the like can be carried out.
The main control device 61 can calculate the volumes of the adsorption and desorption gases in the adsorption and desorption experiments under the condition of ultrasonic excitation and the volumes of the adsorption and desorption gases in the adsorption and desorption experiments without ultrasonic excitation according to the formula.
Wherein, the power range of the ultrasonic generator 21 can be 0kW-3.5kW, and the frequency range of the ultrasonic transducer 22 can be 20kHz-100 kHz. The ultrasonic generator 21 makes the ultrasonic transducer 22 ultrasonically excite the sample chamber 31 at the frequency of 40kHz for 1min at each desorption pressure point by using the power of 1.2kW, and the desorption gas amount and the desorption time are recorded. The relationship between the amount of gas and the equilibrium pressure of adsorption during desorption under ultrasonic excitation is shown in FIG. 5. The methane desorption equilibrium time ratio of the rock sample before and after ultrasonic excitation is shown in fig. 6, and the desorption effect is shown in fig. 7. As can be seen from the figure, under the ultrasonic excitation, the methane desorption amount of the rock sample is not obviously increased, and the methane desorption equilibrium time of the rock sample is obviously reduced. As the desorption pressure decreases, the desorption efficiency increases. The ultrasonic excitation can accelerate the methane to be converted into a free state from an adsorption state on the surface of the shale matrix, promote the desorption of shale gas, promote the methane output, be beneficial to shortening the development time of the shale gas reservoir and improve the exploitation efficiency of the shale gas well.
Therefore, by comparing and analyzing the pressure at the inlet and the outlet of the adsorption and desorption system 30 under each desorption pressure under the ultrasonic excitation action of different vibration modes, frequencies, powers, action time and the like, the influence of different excitation factors on the gas desorption of the rock sample is analyzed, the optimal ultrasonic excitation parameters are preferably selected to achieve the maximum excitation efficiency, an experimental basis is provided for promoting the shale gas to accelerate the desorption, and a new idea is provided for increasing the yield of the shale gas reservoir.
To sum up, the shale rock adsorption and desorption experimental apparatus provided by the embodiment of the present application includes an air source system 10, an ultrasonic wave generation system 20, an adsorption and desorption system 30, a back pressure system 40, a constant temperature system 50 and a data acquisition system 60. The gas source system 10 can provide gas for the adsorption and desorption system 30, so that the rock sample in the adsorption and desorption system 30 can be subjected to adsorption experiment and desorption experiment, and the back pressure system 40 can be used for performing pressure control on the adsorption and desorption system 30. In addition, the ultrasonic wave generating system 20 performs ultrasonic excitation on the rock sample by sending an ultrasonic signal, and the data collecting system 60 collects experimental data of the rock sample in the adsorption experiment and the desorption experiment, and performs analysis processing to obtain an adsorption experiment result and a desorption experiment of the rock sample under different experimental conditions. Therefore, the influence of ultrasonic excitation on adsorption and desorption experiments of shale rock samples can be analyzed, a theoretical basis is provided for shale gas exploitation, and the shale gas well exploitation efficiency is improved.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (7)
1. The shale rock adsorption and desorption experimental device is characterized by comprising an air source system, an ultrasonic generation system, an adsorption and desorption system, a back pressure system, a constant temperature system and a data acquisition system;
the gas source system is connected with one end of the adsorption and desorption system and is used for injecting gas into the adsorption and desorption system;
the adsorption and desorption system is used for accommodating a rock sample and enabling the rock sample to carry out gas adsorption experiments and desorption experiments in the adsorption and desorption system;
the adsorption and desorption system comprises a sample chamber, a first intermediate container and a first displacement pump; the first intermediate container is arranged between the gas source system and the inlet end of the sample chamber and is used for storing gas filled by the gas source system and delivering the gas to the sample chamber; the first displacement pump is connected with the first intermediate container and is used for providing a pressure source for the first intermediate container, adjusting the pressure value of the first intermediate container and measuring the free space volume of the sample chamber;
the back pressure system is connected with the other end of the adsorption and desorption system and is used for setting the pressure of the adsorption and desorption system so as to enable the pressure of the adsorption and desorption system to reach the set pressure required by the desorption experiment;
the ultrasonic generation system is connected with the adsorption and desorption system and is used for sending an ultrasonic signal to carry out ultrasonic excitation on the rock sample; the ultrasonic wave generation system comprises an ultrasonic wave generator and an ultrasonic wave transducer connected with the ultrasonic wave generator;
the ultrasonic generator is used for sending a specific frequency signal to drive the ultrasonic transducer to work;
the ultrasonic transducer is used for emitting ultrasonic signals with corresponding frequencies under the driving of the ultrasonic generator;
the constant temperature system is used for providing a constant set temperature environment for the adsorption and desorption system;
the data acquisition system is connected with the adsorption and desorption system and the back pressure system and is used for acquiring the experimental data of the rock sample in the adsorption experiment and the desorption experiment, and analyzing and processing the experimental data to obtain the adsorption experiment result and the desorption experiment result of the rock sample under different experimental conditions;
the data acquisition system comprises a main control device, the main control device is used for obtaining the reading of the first displacement pump at each equilibrium pressure point in an adsorption experiment, the adsorption experiment result comprises the adsorption gas amount of each equilibrium pressure point, wherein the adsorption gas amount of each equilibrium pressure point is obtained by the main control device according to the reading, the equilibrium pressure and the temperature value of the first displacement pump at each equilibrium pressure point by calculation according to the following formula:
wherein n isiThe adsorption gas amount of the ith equilibrium pressure point; m is the mass of the rock sample particles in the sample chamber; p is a radical ofiIs the ith equilibrium pressure; viThe volume of the pump is fed into the ith balance pressure point; ziIs the gas compression factor at the ith equilibrium pressure; p is a radical ofi-1Is the i-1 th equilibrium pressure; zi-1Is the gas compression factor at the i-1 th equilibrium pressure; r is a molar gas constant; t is the experimental temperature; vfreeIs the free space volume of the sample chamber;
the data acquisition system further comprises a gas flowmeter, the gas flowmeter is connected with the back pressure system, and is used for acquiring the gas flow of the back pressure system of the rock sample after the desorption experiment and sending the gas flow to the main control equipment;
the desorption experiment data comprises desorption gas amount of each desorption balance pressure point, wherein the desorption gas amount of each desorption balance pressure point is calculated by the main control equipment according to the gas flow, the desorption balance pressure and the temperature value collected by the gas flowmeter under each desorption balance pressure point according to the following formula:
wherein, n'iThe desorption gas amount is the ith desorption equilibrium pressure point; p'iIs the ith desorption equilibrium pressure; v'iDesorbing the gas volume in a standard state at the ith desorption equilibrium pressure point; z'iIs the gas compression factor at the ith desorption equilibrium pressure; p'i-1Is the i-1 th desorption equilibrium pressure; z'i-1The gas compression factor is the gas compression factor under the i-1 st desorption equilibrium pressure; p is a radical ofscIs large in standard stateAir pressure; t isscIs the temperature at the standard state; zscIs a gas compression factor under a standard state; vfreeIs the free space volume of the sample chamber; r is a molar gas constant; t is the experimental temperature.
2. The shale rock adsorption and desorption experimental device of claim 1, wherein the adsorption and desorption system comprises a vacuum pump, a first pressure sensor and a second pressure sensor;
the evacuation pump is connected with the sample chamber and is used for carrying out vacuum-pumping treatment on the sample chamber;
the first pressure sensor is arranged at the inlet end of the sample chamber, the second pressure sensor is arranged at the outlet end of the sample chamber, and the first pressure sensor and the second pressure sensor are respectively used for detecting pressure data of the inlet end and the outlet end of the sample chamber.
3. The shale rock adsorption and desorption experiment device of claim 2, wherein the data acquisition system further comprises a data signal collector connected with the main control equipment;
the data signal collector is connected with the first pressure sensor and the second pressure sensor, and is used for obtaining pressure data collected by the first pressure sensor and the second pressure sensor and sending the pressure data to the main control equipment;
and the master control equipment processes and stores the received pressure data and the received gas flow.
4. The shale rock adsorption and desorption experimental device as claimed in claim 1, wherein the gas source system comprises a high-pressure gas cylinder, a booster pump, an air compressor and a first valve;
the high-pressure gas cylinder is connected with one end of the booster pump and is used for providing high-pressure gas;
the booster pump is also connected with an air compressor and an adsorption and desorption system and is used for boosting the gas in the adsorption and desorption system;
the first valve is arranged between the booster pump and the high-pressure gas cylinder.
5. The shale rock adsorption and desorption experiment apparatus of claim 1, wherein the back pressure system comprises a second intermediate container, a second displacement pump, a second relief valve and a back pressure valve;
the inlet of the back pressure valve is connected with the outlet end of the adsorption and desorption system, and the outlet of the back pressure valve is connected with the data acquisition system;
the second intermediate container is connected with the back pressure valve, and the pressure of the back pressure valve is controlled and adjusted by taking gas in the second intermediate container as a pressure transmission medium;
the second displacement pump is connected to one end, far away from the back pressure valve, of the second intermediate container and is used for adjusting the pressure of the second intermediate container;
the second vent valve is connected to the back pressure valve for regulating the pressure of the back pressure valve.
6. The shale rock adsorption and desorption experiment device according to claim 2, wherein a holder is further arranged in the sample chamber and used for placing a rock sample;
the shale rock adsorption and desorption experimental device further comprises a hand-operated pump connected with the holder and used for pressurizing the holder.
7. The shale rock adsorption and desorption experiment device according to claim 1, wherein the constant temperature system comprises a constant temperature box for accommodating the adsorption and desorption system, and a temperature sensor and a temperature controller connected with the temperature sensor are arranged in the constant temperature box;
the temperature sensor is used for collecting a temperature value in the constant temperature box and sending the temperature value to the temperature controller;
the temperature controller is used for controlling the temperature in the constant temperature box according to the received temperature value.
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| CN111855536B (en) * | 2020-08-18 | 2022-02-08 | 西南石油大学 | Method for measuring adsorption of liquid hydrocarbon in reservoir porous medium under high temperature and high pressure |
| CN112002206A (en) * | 2020-08-24 | 2020-11-27 | 中国石油化工股份有限公司 | Shale gas reservoir failure mining experimental method and device |
| CN112903559B (en) * | 2021-01-21 | 2021-11-26 | 中国矿业大学 | Method for testing deformation coupling rule of triple pores of coal rock in non-equilibrium state |
| CN112924354B (en) * | 2021-01-22 | 2022-09-20 | 西南石油大学 | Shale reservoir stress sensitivity experiment evaluation method based on gas diffusion coefficient |
| CN112881230A (en) * | 2021-03-23 | 2021-06-01 | 中国石油大学(华东) | Shale gas vibration desorption test evaluation device and method |
| CN116165096A (en) * | 2023-04-20 | 2023-05-26 | 四川科力特油气技术服务有限公司 | Shale desorption gas testing device and testing method thereof |
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