A multiphase fluid acoustic testing device and method for drilling overflow simulation

Abstract

The present application belongs to the technical field of oil and gas drilling, and particularly relates to a multiphase fluid acoustic and electric testing device and method for drilling overflow simulation. The device is characterized in that: a multifunctional interface integrated on the upper part of the pressure-resistant reaction kettle cylinder is used to complete the injection of different component multiphase fluids and pressure setting; a heating jacket is used to complete the setting of a predetermined temperature; and continuous stirring is used to make the multiphase fluid reach a stable state with uniform composition. Under the conditions of a set temperature and pressure, electrical and acoustic signals are collected to analyze the multiphase fluid. The electrical testing component distinguishes different fluid components by monitoring the changes of resistance and dielectric constant; and the acoustic monitoring component detects the content of bubbles in the fluid through acoustic signals. The acoustic and electric cooperative monitoring can effectively distinguish different overflow types such as gas invasion, oil invasion and water invasion, and overcome the limitations of single monitoring method, thereby providing a reliable technical means for the mechanism research and practical application of downhole overflow monitoring.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas drilling, and particularly relates to a multiphase fluid acoustic and electric testing device and method for drilling overflow simulation. BACKGROUND

[0002] Early and accurate monitoring of downhole overflow in drilling is a key problem faced by deep oil and gas safe drilling. Due to high temperature and high pressure downhole, variable drilling fluid system, and invasion of gas, oil, water and other multiphase fluids, the overflow characteristics are complex, the well control risk is high, and if the overflow is not discovered in time, it will lead to serious blowout accidents. The existing overflow monitoring technology mainly uses the propagation characteristics of ultrasonic waves to monitor the bubbles in the wellbore, but due to the mechanical wave characteristics of ultrasonic waves, it only has good response characteristics to substances with obvious acoustic impedance phase interface (such as bubbles), and for the invasion of formation water, oil and other substances in the drilling process, the ultrasonic monitoring method is no longer applicable. While the formation water, oil, dissolved gas and other substances have different dielectric constants and salinity, which provides a new way to solve this problem: by measuring the dielectric constant and conductivity of the multiphase flow overflow, the existence of salt water, oil and other components can be identified, which becomes the key to make up for the limitations of ultrasonic monitoring method and improve the accuracy of drilling multiphase flow overflow monitoring.

[0003] However, for the complex and variable overflow conditions in deep water and deep oil and gas development, the traditional experimental method is mostly carried out at normal temperature and pressure, which is difficult to simulate the influence of downhole temperature and pressure conditions on the phase state (such as the precipitation and dissolution of dissolved gas) and physical properties of the fluid, the numerical simulation method lacks effective verification, and it is difficult to systematically study the influence of different temperature, pressure, salinity, oil-gas-water ratio and other key parameters on the acoustic and electric signals, which restricts the progress of acoustic and electric collaborative overflow monitoring technology from principle to mature application. SUMMARY

[0004] To solve the above technical problems, the present application provides a multiphase fluid acoustic and electric testing device and method for drilling overflow simulation, and the purpose of the present application is to overcome the shortcomings of the prior art and provide a parameterized multiphase flow acoustic and electric collaborative testing device and method for complex overflow simulation under actual drilling conditions. Through the controllable temperature and pressure system, the actual downhole conditions are simulated, and the preparation of complex multiphase flow formed by the invasion of different fluids (including dissolved gas, salt water, oil, etc.) into different systems (water-based, oil-based) drilling fluid and acoustic and electric signal acquisition are realized, providing reliable experimental device and method for downhole overflow identification.

[0005] The technical problem to be solved by the present application is solved by the following technical scheme: a multiphase fluid acoustic and electric testing device for drilling overflow simulation, comprising a pressure-resistant reaction kettle, a stirring unit and an acoustic and electric monitoring unit;

[0006] The pressure-resistant reaction kettle comprises a heat-conducting cylinder, a sealing end cover and a heating jacket, the sealing end cover is sealingly arranged above the heat-conducting cylinder, and the heating jacket is sleeved outside the heat-conducting cylinder.

[0007] The stirring unit comprises stirring blades arranged at the bottom of the cavity of the heat-conducting cylinder.

[0008] The acoustic and electrical monitoring unit comprises an acoustic monitoring assembly and an electrical testing assembly arranged on the sealing end cover.

[0009] The electrical testing assembly penetrates the sealing end cover and extends into the heat-conducting cylinder, and is used for measuring the conductivity and capacitance of the fluid.

[0010] The acoustic monitoring assembly is used for detecting the content of bubbles in the fluid through acoustic signals.

[0011] The sealing end cover is provided with a multifunctional interface, and the multifunctional interface is communicated with the inner cavity of the heat-conducting cylinder.

[0012] The multifunctional interface is used for injecting fluid and pressurizing into the heat-conducting cylinder. The multifunctional interface can simultaneously serve as a pressurizing port and a fluid circulating port. Through the multifunctional interface, pressurization is carried out, and the heat-conducting cylinder is heated by the heating jacket, so as to simulate the downhole temperature and pressure conditions.

[0013] Preferably, the stirring blades are coated with polytetrafluoroethylene. The polytetrafluoroethylene coating layer makes the stirring blades have chemical inertness and anti-adhesion properties, effectively avoiding pollution of the fluid sample or introduction of interference factors during stirring.

[0014] Preferably, the electrical testing assembly comprises a resistance probe and a dielectric constant probe.

[0015] Preferably, the electrical testing assembly is externally provided with a PEEK insulating protective sleeve. The PEEK insulating protective sleeve can ensure the mechanical strength and long-term stability of the electrical testing assembly in a high-temperature, high-pressure and corrosive multiphase flow environment.

[0016] Preferably, the acoustic monitoring assembly comprises an ultrasonic transducer arranged on the sealing end cover.

[0017] Preferably, the stirring unit is a magnetic stirring system.

[0018] The working principle and advantages of the present application are as follows: during the experiment, the multifunctional interface integrated on the upper part of the pressure-resistant reaction kettle cylinder is used to complete the filling of different component multiphase fluids and pressure setting, the heating jacket is used to complete the setting of the predetermined temperature, and the continuous stirring is used to make the multiphase fluid reach a stable state with uniform composition. Under this temperature and pressure condition, the system collects electrical and acoustic signals to analyze the multiphase flow: the electrical probe distinguishes different fluid components (such as water, oil, and brine) by monitoring the changes of resistance and dielectric constant; and the ultrasonic transducer identifies bubbles by emitting pulses into the cylinder and analyzing the changes of echo signals.

[0019] The test device of the present application integrates the electroacoustic monitoring unit and the high temperature and high pressure environment simulation system, does not need to build a complex and separate experimental system, effectively overcomes the problems of single function and environment simulation distortion of the traditional experimental device. The device can flexibly and accurately adjust and control the working condition parameters according to the experimental requirements, safely realizes the test of the electroacoustic characteristics of the multiphase fluid under different temperature and pressure conditions in the laboratory, and after completing a group of experiments, the fluid and experimental conditions in the cylinder can be emptied and reset, and quickly put into the next group of different experimental conditions, which significantly improves the identification ability and mechanism research depth of the early signs of overflow under the actual working condition of drilling.

[0020] The present application also discloses a multiphase fluid electroacoustic test method for drilling overflow simulation, which utilizes the above-mentioned multiphase fluid electroacoustic test device for drilling overflow simulation and comprises the following steps:

[0021] S1, reference test of the control group: injecting the basic drilling fluid into the sealed heat-conducting cylinder and pressurizing to the target pressure, heating the liquid to the target temperature through the heating jacket, controlling the stirring paddle to stir for a predetermined time, and collecting the acoustic and electrical signals by the acoustic monitoring assembly as the background reference value under the temperature and pressure condition;

[0022] S2, single condition simulation test: adding a single gas phase or liquid phase to the basic drilling fluid, changing the fluid components in the heat-conducting cylinder, simulating any one of the free gas gas invasion condition, the dissolved gas gas invasion condition, the non-mineralized underground water simulation fluid invasion condition and the mineralized underground water simulation fluid invasion condition, and testing the temperature and pressure, collecting the acoustic and electrical signals, and obtaining the electroacoustic response data under the specific condition;

[0023] S3, preparation and test of complex multiphase fluid:

[0024] Injecting the oil-water mixed liquid of the basic drilling fluid and the non-mineralized underground water simulation fluid or the mineralized underground water simulation fluid into the sealed heat-conducting cylinder;

[0025] Injecting the dissolved gas into the heat-conducting cylinder, and testing the pressure and temperature, which are the same as those in step S1;

[0026] The multiphase fluid in the heat conducting cylinder is stirred, so that the gas and the oil-water mixture are fully contacted and reach phase balance under high temperature and high pressure, and a complex multiphase system in a stable state with uniform composition is formed.

[0027] After stopping the stirring, the acoustic signal and the electrical signal are collected.

[0028] S4, multi-working condition data acquisition: by changing any element of the temperature, pressure or composition of the base drilling fluid in step S1, steps S1 to S3 are repeated to obtain the acoustic-electric response data set under different working conditions; the composition of the base drilling fluid mainly controls the water content, and the temperature and pressure affect the gas solubility;

[0029] S5, response relationship construction: based on the data set obtained in step S4, a quantitative corresponding relationship between the fluid components and the acoustic-electric characteristic parameters is established.

[0030] Preferably, the base drilling fluid in step S1 is an oil-based drilling fluid or a water-based drilling fluid.

[0031] Preferably, in step S2, the way of changing the fluid composition includes:

[0032] Direct injection method: pre-configured two-phase fluid is injected into the heat conducting cylinder from the multifunctional interface under pressure;

[0033] Invasive pressurization method: a certain amount of simulated invasive fluid is injected into the base drilling fluid in the heat conducting cylinder from the multifunctional interface under pressure. The present application adopts the principle of "pumping pressurization", which transmits pressure by pumping experimental fluid into the sealed cavity of the pressure-resistant reaction kettle, solving the pollution problem of traditional pneumatic pressurization to the multiphase fluid sample, and ensuring the authenticity and reliability of the experimental data.

[0034] Preferably, the free gas is an inert gas;

[0035] Preferably, the inert gas is nitrogen;

[0036] The dissolved gas is carbon dioxide;

[0037] The non-mineralized underground water simulation fluid is clean water, which is fresh water without mineralized underground water; because the oil-based drilling fluid is a "water-in-oil" emulsion, the water phase is isolated, and the baseline conductivity is extremely low; after simulating water invasion and stirring, the water phase is still a dispersed phase, and the electrical response is mainly the increase of the dielectric constant, and the conductivity has no significant change; and even if the water content is very high, its conductivity is far less than that of salt water containing free ions;

[0038] The mineralized underground water simulation fluid adopts brine, and different concentrations of brine are used to simulate different mineralization degrees. Based on the significant difference in the solubility of different gases in drilling fluid, a gas with stable chemical properties and high safety is scientifically selected. By using the low solubility of nitrogen (inert gas), the typical gas invasion condition mainly in the form of free bubbles can be simulated efficiently and reliably; by using the high solubility and non-flammability of carbon dioxide, the dissolution gas invasion and the phase transition process from the dissolved state to the free state by pressure reduction can be simulated safely, and the simulation effect and experimental safety are considered.

[0039] Compared with the prior art, the beneficial effects of the present application are:

[0040] 1. The device structure is compact, and the operation is convenient. The sound and electricity monitoring unit and the high temperature and high pressure environment simulation system are integrated, the complex temperature and pressure conditions downhole can be accurately reproduced in the laboratory, and the environmental distortion problem caused by the traditional experimental method under normal temperature and pressure is solved.

[0041] 2. The present application innovatively proposes a dissolved gas-free gas phase state control method. By the "high pressure saturation" process, the controllable preparation of complex multiphase fluid (oil, gas, water, dissolved gas) is realized, and the problem of single traditional experimental sample and uncontrollable state is solved.

[0042] 3. By controlling the stirring speed and time, the present application can realize the uniform mixing of the multiphase fluid, realize the uniform dispersion of the bubbles in the drilling fluid when simulating the gas invasion condition, and ensure the state stability of the experimental sample and the repeatability of the test results.

[0043] 4. The present application adopts sound and electricity cooperative monitoring. Acoustic monitoring is sensitive to bubbles, and electrical monitoring is sensitive to fluid components. The cooperation of the two can effectively distinguish different overflow types such as gas invasion, oil invasion and water invasion, and overcome the limitations of single monitoring method.

[0044] 5. The present application establishes a complete experimental system from the baseline test of the control group to the single condition test, and then to the complex multiphase flow test, which can systematically obtain the quantitative mapping relationship of "condition parameter-fluid state-sound and electricity response". Through the standardized experimental process, high-quality sound and electricity response data can be obtained, which provides a reliable technical means for the mechanism research and practical application of downhole overflow monitoring. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 It is a structure schematic view of the multiphase fluid sound and electricity testing device for drilling overflow simulation in the embodiment;

[0046] Figure 2 It is a structure schematic view of the sealing end cover in the embodiment;

[0047] Figure 3 It is a structure schematic view of the stirring paddle;

[0048] Figure 4 The schematic diagram of the acoustic-electricity cooperative multiphase flow monitoring principle for the testing device of the embodiment is shown in the figure;

[0049] Figure 5 The flow chart of the acoustic-electricity cooperative multiphase flow monitoring experiment for the testing method of the embodiment is shown in the figure;

[0050] Figure 6 The trend chart of the acoustic wave amplitude and the first arrival time of the acoustic wave in the drilling fluid under different gas invasion amounts is shown in the figure;

[0051] Figure 7 The trend chart of the dielectric constant and the resistance of the drilling fluid under different gas invasion amounts is shown in the figure;

[0052] Figure 8 The trend chart of the dielectric constant and the resistance of the drilling fluid under different salt water invasion amounts is shown in the figure;

[0053] Figure 9 The trend chart of the dielectric constant and the resistance of the drilling fluid under different fresh water invasion amounts is shown in the figure;

[0054] In the figure, the pressure-resistant reaction kettle 1, the heat-conducting cylinder 11, the sealing end cover 12, and the heating sleeve 13;

[0055] The stirring paddle 2, the acoustic monitoring assembly 3, the electrical testing assembly 4, the resistance probe 41, and the dielectric constant probe 42;

[0056] The multifunctional interface 100;

[0057] The sealing inner sleeve 121, the sealing outer sleeve 122, the sealing ring 123, and the electrical analyzer clamping device 124;

[0058] The fixing column 1211, the sealing column 1212, the limiting hole 1221, and the sealing flange 1222. DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings.

[0060] The following embodiments are used to further illustrate and verify the present application, but the protection scope of the present application is not limited to these specific embodiments. Since the core of the present application is to integrate high-temperature and high-pressure environment simulation, parameterized multiphase fluid preparation, and acoustic-electricity synchronous monitoring, and to build a complete set of indoor experimental device and method, therefore, the specific implementation of these innovative parts will be elaborated in detail in the present specification. For those skilled in the art, the conventional technical means involved in the implementation of the present application (such as the selection of the signal collector, the conventional connection mode of the heating sleeve and the pressure pump, etc.) can be realized according to the existing technology, and will not be described here.

[0061] As Figure 1As shown, the embodiment provides a multiphase fluid acoustic and electric testing device for drilling overflow simulation, which comprises a pressure-resistant reaction kettle 1, a stirring unit and an acoustic and electric monitoring unit. The pressure-resistant reaction kettle 1 serves as the main structure of the device and is used for containing the multiphase fluid for experiment.

[0062] The pressure-resistant reaction kettle 1 comprises a heat-conducting cylinder 11, a sealing end cover 12 and a heating jacket 13. The sealing end cover 12 is sealingly arranged above the heat-conducting cylinder 11, and a sealing ring is arranged between the sealing end cover 12 and the heat-conducting cylinder 11. The heating jacket 13 is sleeved outside the heat-conducting cylinder 11.

[0063] As shown in the Figure 1 stirring unit comprises a stirring paddle 2 arranged at the bottom of the cavity of the heat-conducting cylinder 11. The stirring paddle 2 is coated with polytetrafluoroethylene, and the structure of the stirring paddle 2 is as shown in the Figure 3 .

[0064] The stirring unit is a magnetic stirring system, which comprises a magnetic stirring impeller arranged in the heat-conducting cylinder 11 and an external driving device, and is used for realizing uniform mixing of the multiphase fluid.

[0065] The acoustic and electric monitoring unit comprises an acoustic monitoring assembly 3 and an electric testing assembly 4 arranged on the sealing end cover 12.

[0066] The electric testing assembly 4 penetrates the sealing end cover 12 and extends into the heat-conducting cylinder 11, and is used for measuring the conductivity and capacitance of the fluid.

[0067] Specifically, the electric testing assembly 4 comprises a resistance probe 41 and a dielectric constant probe 42. The electric testing assembly 4 is externally provided with a PEEK insulation protective sleeve. The resistance probe 41 sensitively detects the invasion of brine (salinity) by measuring the change of the conductivity of the fluid; and the dielectric constant probe 42 identifies the existence of oil, dissolved gas and clean water by measuring the dielectric property of the fluid.

[0068] The acoustic monitoring assembly 3 is used for detecting the content of bubbles in the fluid through acoustic signals. The acoustic monitoring assembly 3 comprises an ultrasonic transducer arranged on the sealing end cover 12, and ultrasonic monitoring is performed by using the pulse echo method. The ultrasonic transducer is arranged in the sealing end cover 12. The ultrasonic transducer emits ultrasonic pulses to the fluid in the cylinder and receives echo signals. The attenuation of the echo signals can reflect the content of bubbles in the multiphase fluid.

[0069] A multifunctional interface 100 is arranged on the sealing end cover 12, and the multifunctional interface 100 communicates with the inner cavity of the heat-conducting cylinder 11.

[0070] The multifunctional interface 100 is used for injecting fluid and pressurizing into the heat-conducting cylinder 11.

[0071] In the embodiment, asFigure 2 As shown, the sealing end cover 12 comprises a sealing inner sleeve 121 and a sealing outer sleeve 122, the sealing inner sleeve 121 comprises a fixed column 1211 and a sealing column 1212 arranged from top to bottom, the sealing outer sleeve 122 is provided with a limiting hole 1221 in the center, the sealing outer sleeve 122 is threadedly connected with the heat-conducting cylinder 11, a sealing flange 1222 is arranged above the sealing outer sleeve 122 and cooperates with the upper end surface of the heat-conducting cylinder 11, the ultrasonic transducer is inlaid in the lower end of the sealing outer sleeve 122, the upper end surface of the sealing column 1212 is in contact with the lower end surface of the sealing outer sleeve 122, and a sealing ring 123 is arranged on the sealing column 1212 and sealingly connected with the heat-conducting cylinder 11. The sealing outer sleeve 122 is sealed by thread sealing and end surface sealing to ensure the sealing property with the heat-conducting cylinder 11, and the sealing inner sleeve 121 is under the pressurized environment in the sealing ring 123 and the heat-conducting cylinder 11 to ensure the sealing property between the sealing inner sleeve 121 and the heat-conducting cylinder 11 and the sealing outer sleeve 122.

[0072] The fixed column 1211 is arranged in the limiting hole 1221, the multifunctional interface 100, the resistance probe 41 and the dielectric constant probe 42 are arranged through the fixed column 1211 and the sealing column 1212, and the upper ends of the resistance probe 41 and the dielectric constant probe 42 are respectively connected with the electrical analysis instrument clamping device 124 through the fixed column 1211. The impedance analyzer and the capacitance analyzer are respectively connected with the electrical analysis instrument clamping device 124.

[0073] As shown in Figure 4 , Figures 6-9 , the testing device provided by the application has the following action mechanism:

[0074] 1. As shown in Figure 8 and Figure 9 , when there is a high-conductivity fluid such as formation water (brine) in the multiphase flow, the electrical characteristics will change obviously: the brine as a high-mineralization conductivity phase will enhance the conductivity of the fluid, resulting in a decrease in the resistance value measured by the resistance probe; at the same time, since the dielectric constant of water is usually higher than that of oil phase and drilling fluid base fluid, the capacitance value measured by the dielectric constant probe will also increase accordingly. In terms of acoustic response, the acoustic impedance of the formation water is relatively close to that of the drilling fluid, so the scattering effect on the acoustic wave signal is weak, and the amplitude attenuation of the acoustic wave is not obvious.

[0075] 2. As shown in Figure 6 , when there is a gas bubble in the multiphase flow, since there is a significant acoustic impedance difference between the gas bubble and the liquid, the scattering and energy attenuation of the acoustic wave occur at the gas-liquid interface, resulting in a decrease in the signal amplitude received by the acoustic wave receiving device and a decrease in the acoustic wave propagation speed.

[0076] 3. As shown in Figure 6 and Figure 7As shown, when there is dissolved gas in the multiphase flow, because the dissolved gas is dispersed in the liquid phase in the form of molecules, no obvious gas-liquid interface is formed, and therefore the effect on the acoustic signal is weak. In terms of electrical response, the dissolved gas can reduce the dielectric constant of the liquid phase, resulting in a decrease in the capacitance value, and has relatively small effect on the resistance value.

[0077] The present application can effectively distinguish the components of the multiphase flow through the synergy of acoustic and electric signals, and realize accurate discrimination of the overflow type.

[0078] As shown in the flow chart of the experimental method of the present embodiment, the specific steps are as follows: Figure 5

[0079] Embodiment 1

[0080] This embodiment is a control example, and is realized based on the test device provided in the present embodiment.

[0081] S1. Connect the multifunctional interface 100 of the pressure-resistant reaction kettle 1 to the injection pump through the high-pressure pipeline, inject pure oil-based drilling fluid into the barrel of the pressure-resistant reaction kettle 1, pressurize the pressure-resistant reaction kettle 1 to 40 MPa, and heat the liquid in the pressure-resistant reaction kettle 1 to 90°C through the heating jacket 13.

[0082] S2. After stirring at a speed of 400 rpm for 2 minutes to ensure uniformity, collect the acoustic and electric signals by using the electrical test assembly 4.

[0083] S3. Record the amplitude A0 of the acoustic signal, the acoustic velocity V0, the dielectric constant ε0 and the resistance value σ0 as the reference values for all subsequent examples.

[0084] Embodiment 2

[0085] This embodiment is a test of the acoustic and electric response of the gas invasion condition (free gas bubbles), and aims to verify the high sensitivity of the acoustic monitoring assembly to the gas bubbles and obtain the acoustic and electric response characteristics of the gas-liquid two-phase flow.

[0086] Pump 160 mL of oil-based drilling fluid into the barrel of the pressure-resistant reaction kettle 1 through the multifunctional interface 100.

[0087] Pump nitrogen into the barrel of the pressure-resistant reaction kettle 1 through the multifunctional interface 100, which achieves two purposes at the same time: simulates gas invasion and raises the system pressure to 40 MPa.

[0088] Heat the liquid in the pressure-resistant reaction kettle 1 to 90°C through the heating jacket 13.

[0089] Start the magnetic stirring system and stir at a high speed of 800 rpm for 3 minutes to make the gas be strongly sheared and dispersed into small bubbles, simulating bubbly flow.

[0090] ​Stop stirring, and after standing stably, collect the acoustic and electric signals.

[0091] Results and analysis:

[0092] Acoustic response: Compared with Example 1, the amplitude of the acoustic wave signal attenuates (A << A0), and the speed of sound decreases significantly (V < V0). This indicates that the acoustic method is extremely sensitive to the presence of bubbles.

[0093] Electrical response: Compared with Example 1, the dielectric constant of the unit decreases (ε < ε0). This is because the solubility of nitrogen gas is extremely low under this temperature and pressure condition, and it mainly exists in the form of free bubbles; the dielectric constant of the bubbles is much lower than that of the liquid phase, which will significantly reduce the overall dielectric constant of the mixed fluid. There is no significant change in conductivity.

[0094] Example 3

[0095] This example is the acoustic and electric response test of dissolved gas invasion conditions. This example aims to demonstrate the monitoring capability of the device for dissolved gas invasion and compare the response differences between dissolved gas invasion and free gas invasion.

[0096] In an external high-pressure saturation tank, the oil-based drilling fluid was stirred for 12 hours at 60°C in a CO2 environment of 5 MPa to prepare a dissolved gas saturated sample.

[0097] The saturated sample was pumped into the pressure-resistant reaction kettle 1 cylinder through the multifunctional interface 100, and was pressurized to 40 MPa (to suppress the precipitation of dissolved gas) and heated to 90°C.

[0098] Acoustic and electric tests were performed, and acoustic and electric signals were collected.

[0099] Results and analysis:

[0100] Acoustic response: Compared with Example 1, there is no significant change in the amplitude of the acoustic wave and the speed of sound (A ≈ A0, V ≈ V0). Because dissolved gas does not form an acoustic impedance interface, it has a weak effect on the propagation of acoustic waves.

[0101] Electrical response: Compared with Example 1, the dielectric constant decreases (ε < ε0). Although CO2 has been dissolved, the presence of its molecules still changes the overall polarization characteristics of the oil-based drilling fluid, resulting in a decrease in dielectric constant. There is no significant change in conductivity.

[0102] Example 4

[0103] This example is the acoustic and electric response test of water invasion conditions. This example aims to verify the response of the electrical test assembly to the invasion of non-mineralized underground water simulation fluid (clean water).

[0104] An oil-based drilling fluid containing 30% clean water was pre-configured.

[0105] The premixed sample was pumped into the pressure vessel 1 through the multifunctional interface 100, and an experimental environment of 90°C and 40MPa was established.

[0106] The magnetic stirring system was started (400rpm), and after stabilization, the acoustic and electrical tests were carried out.

[0107] The results and analysis are as follows:

[0108] Acoustic response: Compared with Example 1, the acoustic signal did not change significantly (A≈A0, V≈V0).

[0109] Electrical response: Compared with Example 1, the dielectric constant increased significantly (ε>ε0), and the conductivity did not change significantly (σ≈σ0).

[0110] Example 5

[0111] This example is an acoustic and electrical response test under the condition of saltwater invasion. This example aims to verify the response of the electrical test assembly to high salinity saltwater invasion and demonstrate its ability to distinguish between water invasion.

[0112] An oil-based drilling fluid containing 30% saltwater phase (5% NaCl solution) was prepared in advance.

[0113] The premixed sample was pumped into the pressure vessel 1 through the multifunctional interface 100, and an experimental environment of 90°C and 40MPa was established.

[0114] The magnetic stirring system was started (400rpm), and after stabilization, the acoustic and electrical tests were carried out.

[0115] The results and analysis are as follows:

[0116] Acoustic response: Compared with Example 1, the acoustic signal did not change significantly (A≈A0, V≈V0).

[0117] Electrical response: Compared with Example 1, the dielectric constant increased significantly (ε>ε0), and the conductivity increased sharply (σ>>σ0) because saltwater provides a large number of free-moving ions.

[0118] Through comparison with Example 4, it can be seen that although the acoustic response is consistent and the dielectric constant increases, through the combined characteristics of "dielectric constant increases and conductivity increases sharply" in the electrical signal, water invasion and saltwater invasion can be clearly and accurately distinguished.

[0119] Example 6

[0120] This example is an acoustic and electrical response test of complex multiphase fluid of oil, gas and water. This example aims to verify the monitoring and distinguishing ability of the device under the condition of complex multiphase fluid invasion.

[0121] Through the multifunctional interface 100, the pre-configured oil-based drilling fluid mixed with salt water (with a salt water phase proportion of 30%) is pressurized and injected into the pressure-resistant reaction kettle 1 barrel.

[0122] Through the multifunctional interface 100, carbon dioxide (CO2) gas is pressurized and injected into the pressure-resistant reaction kettle 1 barrel, the system is pressurized to 40 MPa, and heated to 90°C through a flexible heating jacket.

[0123] The magnetic stirring system is started, and stirring is continued at a speed of 600 rpm for 10 minutes. CO2 is fully contacted with the oil-water mixture and phase equilibrium is reached.

[0124] During this process, CO2 gas is fully contacted with the oil-water mixture under high temperature and high pressure and phase equilibrium is reached. During this process, part of the CO2 is dissolved in the oil and salt water, and the other part exists in the form of free bubbles.

[0125] Stop stirring, and under the condition that the system maintains a pressure of 40 MPa, acoustic and electrical signal acquisition is performed.

[0126] The comparison of different invasion conditions of examples 2-6 and single monitoring methods is shown in Table 1:

[0127] Results and analysis:

[0128] Acoustic response: the amplitude of the acoustic wave is significantly attenuated (A << A0), and the speed of sound is significantly reduced (V < V0). This clearly confirms the presence of free bubbles in the fluid.

[0129] Electrical response: the dielectric constant is higher than the baseline value (ε > ε0), but lower than the pure salt water invasion condition (ε < ε_Example 5). This is because on the one hand the salt water increases the dielectric constant of the oil-based drilling fluid, and on the other hand the dissolved and free gas reduces it. The conductivity sharply rises (σ >> σ0), consistent with the salt water invasion characteristics of Example 5.

[0130] The comparison of different invasion conditions of examples 2-6 and single monitoring methods is shown in Table 1:

[0131] Table 1 Comparison of recognition ability of different monitoring methods for each invasion condition

[0132]

[0133] The above comparison results show that the acoustic monitoring assembly 3 and the electrical testing assembly 4 are used for acoustic and electrical cooperative monitoring, which can effectively identify free gas invasion, dissolved gas invasion, fresh water invasion, salt water invasion, and gas-water composite invasion in different conditions.

Claims

1. A multiphase fluid acoustic-electric testing method for simulating drilling overflow, employing a multiphase fluid acoustic-electric testing device for simulating drilling overflow, characterized in that... The multiphase fluid acoustic-electric testing device for drilling overflow simulation includes a pressure-resistant reactor (1), a stirring unit, and an acoustic-electric monitoring unit; The pressure-resistant reactor (1) includes a heat-conducting cylinder (11), a sealing end cap (12), and a heating sleeve (13). The sealing end cap (12) is sealed above the heat-conducting cylinder (11), and the heating sleeve (13) is fitted on the outside of the heat-conducting cylinder (11). The stirring unit includes stirring blades (2) disposed at the bottom of the cavity of the heat-conducting cylinder (11). The acoustic-electric monitoring unit includes an acoustic monitoring component (3) and an electrical testing component (4) disposed on a sealed end cap (12); the electrical testing component (4) includes a resistance probe (41) and a dielectric constant probe (42). The electrical testing component (4) extends through the sealed end cap (12) into the heat-conducting cylinder (11) to measure the conductivity and capacitance of the fluid; The acoustic monitoring component (3) is used to detect the content of bubbles in the fluid by means of sound wave signals; the acoustic monitoring component (3) includes an ultrasonic transducer disposed on the sealed end cap (12); The sealing end cap (12) is provided with a multi-functional interface (100), which is connected to the inner cavity of the heat-conducting cylinder (11); The multi-functional interface (100) is used for injecting fluid and pressurizing the heat-conducting cylinder (11); The multiphase fluid acoustic-electric testing method for simulating drilling overflow includes the following steps: S1, control group benchmark test: inject basic drilling fluid into the sealed heat-conducting cylinder (11) and pressurize it to the target pressure. Heat the liquid to the target temperature through the heating jacket (13). After controlling the stirring blade (2) to stir for a predetermined time, use the acoustic monitoring component (3) to collect the acoustic wave signal and electrical signal as the background benchmark value under the temperature and pressure conditions. S2, Single working condition simulation test: Add a single gas phase or liquid phase to the basic drilling fluid, change the fluid composition in the heat-conducting cylinder (11), and simulate any working condition such as free gas intrusion, dissolved gas intrusion, non-mineralized groundwater simulated fluid intrusion and mineralized groundwater simulated fluid intrusion. The test temperature and pressure are the same as in step S1. Acquire acoustic and electrical signals to obtain acoustic and electrical response data under specific working conditions. The free gas is an inert gas; Carbon dioxide is used as the dissolved gas; The dissolved gas intrusion condition is specifically achieved through a "high-pressure saturation" process, in which the base drilling fluid is stirred in a carbon dioxide environment at a specific temperature and pressure to prepare a dissolved gas saturated sample. The fluid used to simulate non-mineralized groundwater is clean water; The simulated fluid for mineralized groundwater is brine; S3. Preparation and Testing of Complex Multiphase Fluids: Inject a mixture of base drilling fluid and non-mineralized groundwater simulation fluid or mineralized groundwater simulation fluid into a sealed heat-conducting cylinder (11); Dissolved gas is injected into the heat-conducting cylinder (11), and the pressure and temperature are tested in the same way as in step S1. The multiphase fluid inside the heat-conducting cylinder (11) is stirred so that the gas and the oil-water mixture can fully contact each other under high temperature and high pressure and reach phase equilibrium, forming a complex multiphase system with uniform composition and stable state. After stirring is stopped, acoustic and electrical signals are acquired. S4. Acquisition of multi-condition data: By changing any element of temperature, pressure or composition of the basic drilling fluid in step S1, repeat steps S1 to S3 to obtain acoustic and electrical response datasets under different conditions. S5. Response Relationship Construction: Based on the dataset obtained in step S4, establish a quantitative correspondence between fluid components and acoustic-electric characteristic parameters.

2. The multiphase fluid acoustic-electric testing method for simulating drilling overflow according to claim 1, characterized in that: The base drilling fluid in step S1 is either oil-based or water-based.

3. The multiphase fluid acoustic-electric testing method for simulating drilling overflow according to claim 1, characterized in that: In step S2, the methods for changing the fluid composition include: Direct injection method: A pre-prepared two-phase fluid is injected under pressure into the heat-conducting cylinder (11) through the multi-functional interface (100); Intrusion pressurization method: A fixed amount of simulated intrusion fluid is injected into the base drilling fluid inside the heat-conducting cylinder (11) through the multi-functional interface (100) under pressure.

4. The multiphase fluid acoustic-electric testing method for simulating drilling overflow according to claim 1, characterized in that: Nitrogen is selected as the inert gas.

5. The multiphase fluid acoustic-electric testing method for drilling overflow simulation according to claim 1, characterized in that: The stirring blade (2) is coated with polytetrafluoroethylene.

6. The multiphase fluid acoustic-electric testing method for simulating drilling overflow according to claim 1, characterized in that: The electrical testing component (4) is provided with a PEEK insulating protective sleeve.

7. The multiphase fluid acoustic-electric testing method for drilling overflow simulation according to claim 1, characterized in that: The stirring unit is a magnetic stirring system.

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