Rock parameter inversion method and device for pressure-maintaining coring by using ultrasonic waves

Abstract

The invention discloses a rock parameter inversion method for pressure-maintaining coring by using ultrasonic waves. The rock parameter inversion method comprises the following steps: S100, aligning a transmitter and a receiver with a through hole in a core barrel; s200, starting to send and receive an ultrasonic signal to obtain the following data: longitudinal wave propagation time; transverse wave propagation time; and S300, calculating the following parameters of the rock, including the longitudinal wave velocity, the transverse wave velocity, the pressure sensitivity coefficient and the longitudinal wave modulus of the pressure maintaining rock core. According to the invention, pressure-maintaining coring is combined with a curved surface probe ultrasonic testing technology, so that more accurate and comprehensive detection of a rock core sample is realized, data closer to an in-situ real condition is obtained, and reliable data support is provided for research in related fields.

Description

Technical Field

[0001] This invention relates to the field of rock data processing methods, and in particular to a method and apparatus for inverting rock parameters using ultrasonic waves in pressure-controlled coring. Background Technology

[0002] In many fields such as geological exploration and oil extraction, accurate detection of the characteristics of underground rocks and reservoirs is crucial. Traditional detection technologies often face problems such as insufficient accuracy and distorted sample information when dealing with complex geological conditions.

[0003] Current testing equipment suffers from the following drawbacks: its testing functions are limited, and it has not formed a complete field testing technology system; some key testing technologies have not yet been integrated into the pressure-holding coring device; traditional planar probes are difficult to fully conform to the curved surface of rock samples, resulting in unstable ultrasonic wave propagation paths, severe signal attenuation, and a significant decrease in detection accuracy. Furthermore, repressurizing after coring to restore the original state not only increases equipment costs but also reduces testing efficiency and accuracy, failing to meet the current needs of deep-earth resource development. Summary of the Invention

[0004] This invention aims to provide a method for inverting rock parameters using ultrasonic waves in pressure-controlled coring. By combining pressure-controlled coring with ultrasonic testing technology using curved probes, this method achieves more accurate and comprehensive detection of core samples, obtaining data that more closely approximates the actual in-situ conditions, and providing reliable data support for research in related fields.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] This invention discloses a method for inverting rock parameters using ultrasonic waves in pressure-holding coring, comprising the following steps:

[0007] S100: The center rod pulls the core inside the core cylinder to the predetermined test position in the pressure-holding chamber. The center rod then retracts, ensuring a stable pressure environment inside the chamber. The ultrasonic transmitter and receiver in the curved ultrasonic testing device are aligned with the through holes on the core cylinder.

[0008] S200: After coring is completed, move the ultrasonic transmitter and receiver to fully contact the outer wall of the core, and begin sending and receiving ultrasonic signals to obtain the following data:

[0009] Longitudinal wave propagation time The total time delay from the ultrasonic transmitter to the ultrasonic receiver (including system fixed delay) Transverse wave propagation time ;

[0010] Among the known geometric parameters are: the distance between the transmitter and receiver points L; and the separately measured mixing density. ;

[0011] S300: Estimate the following parameters of the rock:

[0012] S310: Ultrasonic transmitters and receivers are arranged along the diameter on both sides of the core to measure the longitudinal wave velocity of the pressurized core.

[0013]

[0014] in For the longitudinal wave velocity under pressure-holding conditions, For the distance between the transmitter and receiver (known), ≤ ), The diameter of the core tube, Set a fixed delay for the system.

[0015] S320: Based on the measurement of longitudinal wave travel time and multi-pressure point measurements, the pressure sensitivity coefficient can be derived. and These can respectively reflect the relative rate of change of longitudinal wave velocity and the relative rate of change of longitudinal wave modulus caused by a unit pressure change, and are used to quantitatively describe the stiffness evolution of rocks under pressure-holding pore water:

[0016]

[0017] ;

[0018] S330: Defined in square form as a normalized longitudinal stiffness index, used for relative comparison of different samples or pressure conditions. The specific formula is as follows:

[0019]

[0020] in, To maintain the longitudinal wave modulus of the core, For the longitudinal wave velocity under pressure-holding conditions, This refers to the density of the rock under pressure conditions.

[0021] Preferably, in step S310, by measuring the density and shear wave velocity of the pressurized core separately, a series of physical and mechanical parameters of the pressurized core can be inverted by combining them with the longitudinal wave velocity measured by this device:

[0022] Poisson's ratio :

[0023]

[0024] Young's modulus :

[0025] ,

[0026] In addition, bulk modulus and shear modulus can also be converted from Young's modulus and Poisson's ratio.

[0027] Preferably, in step S310, the system fixed delay includes a transducer, a coupling layer, and an electrical delay.

[0028] An apparatus for implementing the above parameter inversion method, characterized in that it includes a core sampling device and an ultrasonic testing device;

[0029] The core sampling device includes an outer tube and a central rod. A core cylinder is installed inside the outer tube. The central rod is driven to the tail end of the core cylinder. A sealing valve is provided at the head end of the outer tube. An equipment hole is provided on the side wall of the head end of the outer tube. An inspection hole is provided on the side wall of the head end of the core cylinder.

[0030] The ultrasonic testing device includes an ultrasonic transmitter and an ultrasonic receiver. The ultrasonic transmitter and ultrasonic receiver are inserted into the device hole and located at both ends of the outer tube in the radial direction. The ultrasonic transmitter and ultrasonic receiver are adapted to the test hole.

[0031] Preferably, the sealing valve includes a valve disc and a valve seat, with the valve disc edge hinged to the valve seat.

[0032] Preferably, the tail end of the ultrasonic transmitter is a first limiting part, the middle part of the ultrasonic transmitter is provided with a first sealing ring, and the head end of the ultrasonic transmitter is a curved surface that bulges towards the core cylinder.

[0033] Preferably, the tail end of the ultrasonic receiver is a second limiting part, the middle part of the ultrasonic receiver is provided with a second sealing ring, and the head end of the ultrasonic receiver is a curved surface facing the concavity of the core cylinder.

[0034] The beneficial effects of this invention are:

[0035] This invention integrates point load and ultrasonic testing functions to achieve acoustic property detection of pressurized rock cores and in-situ point load testing, improving data accuracy and testing efficiency. This device can more comprehensively evaluate the mechanical and acoustic properties of rock cores, providing more reliable technical support for oil and gas exploration and extraction, and coal resource development. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the present invention;

[0037] Figure 2 This is a schematic diagram illustrating the working state of the present invention;

[0038] Figure 3 This is a schematic diagram of the ultrasonic transmitter along its axis.

[0039] Figure 4 This is a circumferential schematic diagram of an ultrasonic generator;

[0040] Figure 5 This is a schematic diagram of the axial direction of the ultrasonic receiver.

[0041] In the diagram: 1-Central rod, 2-Outer tube, 3-Core tube, 4-Ultrasonic transmitter, 5-Ultrasonic receiver, 6-Valve disc, 7-Detection hole, 8-Valve seat, 9-First limiting part, 10-First sealing ring, 11-Ultrasonic probe, 12-Second limiting part, 13-Second sealing ring. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings.

[0043] This invention includes the following steps:

[0044] S100: The central rod 1 pulls the core from the core cylinder 3 to the predetermined test position in the pressure-holding chamber. As the central rod 1 retracts, the valve 6, which was originally open, loses its support and automatically closes, ensuring a stable pressure environment inside the chamber. The curved ultrasonic testing device includes an ultrasonic transmitter 4 and an ultrasonic receiver 5, which are aligned with the detection hole 7 on the core cylinder 3, allowing the sound waves to act directly on the core.

[0045] S200: After coring is completed, move the ultrasonic transmitter 4 and ultrasonic receiver 5 to ensure they are fully against the outer wall of the core, achieving good coupling. Begin sending and receiving ultrasonic signals, obtaining the following data: longitudinal wave propagation time. The total time delay from transmitter to receiver includes the system's fixed delay. Transverse wave propagation time Known geometric parameters: The distance L between the transmitter and receiver points is determined by the device structure; the mixing density ρ is measured separately. e .

[0046] S300: Parameters of the rock to be estimated:

[0047] S310: Ultrasonic transmitters 4 and ultrasonic receivers 5 are arranged along the diameter on both sides of the core to measure the longitudinal wave velocity of the pressurized core.

[0048]

[0049] in For the longitudinal wave velocity under pressure-holding conditions, Given that the distance between the transmitter and receiver is known, ≤ , The system includes a fixed delay transducer, coupling layer, and electrical delay. Additionally, by separately measuring the density and shear wave velocity of the pressurized core, a series of physical and mechanical parameters of the pressurized core can be retrieved by combining the longitudinal wave velocity measured by this device.

[0050] By measuring the longitudinal wave travel time, the pressure sensitivity coefficient can also be derived based on multi-pressure point measurements. and This method quantitatively describes the stiffness evolution of rocks under pressure-maintaining pore water, or forms a "longitudinal wave velocity-pore water pressure curve" under pressure-maintaining conditions. It can also be defined in a squared form as a normalized longitudinal stiffness index for relative comparison of different samples or pressure conditions.

[0051] in, To maintain the longitudinal wave modulus of the core, For the longitudinal wave velocity under pressure-holding conditions, This represents the density of the rock under pressure conditions.

[0052] like Figure 1-5 As shown, the apparatus used to implement the above inversion method includes a core sampling device and an ultrasonic testing device;

[0053] The core sampling device includes an outer tube 2 and a central rod 1. A core cylinder 3 is installed inside the outer tube 2. The central rod 1 is connected to the tail end of the core cylinder 3. A sealing valve is provided at the head end of the outer tube 2. An equipment hole is provided on the side wall of the head of the outer tube 2. An inspection hole 7 is provided on the side wall of the head of the core cylinder 3.

[0054] The ultrasonic testing device includes an ultrasonic transmitter 4 and an ultrasonic receiver 5. The ultrasonic transmitter 4 and the ultrasonic receiver 5 are inserted into the device hole and are located at both ends of the outer tube 2 in the radial direction. The ultrasonic transmitter 4 and the ultrasonic receiver 5 are adapted to the test hole 7.

[0055] The sealing valve includes a valve disc 6 and a valve seat 8, with the valve disc 6 hinged to the valve seat 8.

[0056] The ultrasonic transmitter 4 has a first limiting part 9 at its tail end, a first sealing ring 10 in the middle of its middle, a curved surface protruding towards the core cylinder 3 at its head end, and an ultrasonic probe 11 at its head end.

[0057] Similar in structure to the ultrasonic transmitter 4, the ultrasonic receiver 5 has a second limiting part 12 at its tail end, a second sealing ring 13 in its middle, and a curved surface at its head end facing the core cylinder 3.

[0058] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A method for inverting rock parameters using ultrasonic waves in pressure-holding coring, characterized in that... Includes the following steps: S100: The center rod (1) pulls the core in the core tube (3) to the predetermined test position of the pressure chamber. The center rod (1) is withdrawn to ensure the stability of the pressure environment inside the chamber. The ultrasonic transmitter (4) and ultrasonic receiver (5) in the curved ultrasonic testing device are aligned with the test hole (7) on the core tube (3). S200: After the core sampling is completed, move the ultrasonic transmitter (4) and ultrasonic receiver (5) to fully fit against the outer wall of the core, and start sending and receiving ultrasonic signals to obtain the following data: Longitudinal wave propagation time It is the total time delay from the ultrasonic transmitter (4) to the ultrasonic receiver (5) (including the system fixed delay). Transverse wave propagation time ; The known geometric parameters include: the distance between the transmitter and receiver points L; and the equivalent density of the pressurized core measured separately. ; S300: Estimate the following parameters of the rock: S310: Ultrasonic transmitters (4) and ultrasonic receivers (5) are arranged on both sides of the core along the diameter to measure the longitudinal wave velocity of the core under pressure-holding conditions. and transverse wave velocity : in For the longitudinal wave velocity under pressure-holding conditions, For the longitudinal wave velocity under pressure-holding conditions, For the distance between the transmitter and receiver (known), ≤ ), The diameter of the core tube (3) is Set a fixed delay for the system. S320: Based on the measurement of longitudinal wave travel time and multi-pressure point measurements, the pressure sensitivity coefficient can be derived. and These can respectively reflect the relative rate of change of longitudinal wave velocity and the relative rate of change of longitudinal wave modulus caused by a unit pressure change, and are used to quantitatively describe the stiffness evolution of rocks under pressure-holding pore water: ； S330: Defined in square form as a normalized longitudinal stiffness index, used for relative comparison of different samples or pressure conditions. The specific formula is as follows: in, To maintain the longitudinal wave modulus of the core, For the longitudinal wave velocity under pressure-holding conditions, This represents the density of the rock under pressure conditions.

2. The parameter inversion method according to claim 1, characterized in that: In step S310, by measuring the density and shear wave velocity of the pressurized core separately, a series of physical and mechanical parameters of the pressurized core can be inverted by combining them with the longitudinal wave velocity measured by this device: Poisson's ratio : Young's modulus : 。 3. The parameter inversion method according to claim 1, characterized in that: In step S310, the system fixed delay includes the transducer, coupling layer, and electrical delay.

4. An apparatus for implementing the parameter inversion method according to any one of claims 1-3, characterized in that: Includes a core sampling device and an ultrasonic testing device; The core sampling device includes an outer tube (2) and a central rod (1). A core cylinder (3) is installed inside the outer tube (2). The central rod (1) is connected to the tail end of the core cylinder (3). A sealing valve is provided at the head end of the outer tube (2). An equipment hole is provided on the side wall of the head of the outer tube (2). An inspection hole (7) is provided on the side wall of the head of the core cylinder (3). The ultrasonic testing device includes an ultrasonic transmitter (4) and an ultrasonic receiver (5). The ultrasonic transmitter (4) and the ultrasonic receiver (5) are inserted into the device hole. The ultrasonic transmitter (4) and the ultrasonic receiver (5) are located at both ends of the outer tube (2) in the radial direction. The ultrasonic transmitter (4) and the ultrasonic receiver (5) are adapted to the detection hole (7).

5. The apparatus according to claim 4, characterized in that: The sealing valve includes a valve disc (6) and a valve seat (8), with the valve disc (6) hinged to the valve seat (8).

6. The apparatus according to claim 4, characterized in that: The tail end of the ultrasonic transmitter (4) is the first limiting part (9), the middle part of the ultrasonic transmitter (4) is provided with the first sealing ring (10), and the head end of the ultrasonic transmitter (4) is a curved surface that protrudes towards the core cylinder (3).

7. The apparatus according to claim 4, characterized in that: The tail end of the ultrasonic receiver (5) is the second limiting part (12), the middle part of the ultrasonic receiver (5) is provided with a second sealing ring (13), and the head end of the ultrasonic receiver (5) is a curved surface that is recessed towards the core tube (3).

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