CN-122027914-A - Mud pulse-based logging-while-drilling data coding modulation and demodulation method and device

CN122027914ACN 122027914 ACN122027914 ACN 122027914ACN-122027914-A

Abstract

The application relates to the technical field of logging while drilling, in particular to a method and a device for coding and modulating logging while drilling data based on mud pulse, a method and a device for coding and demodulating logging while drilling data based on mud pulse, and a logging while drilling data transmission system. The method comprises the steps of encoding logging while drilling data to obtain symbol data, obtaining set modulation frequencies corresponding to the symbol data based on a set corresponding relation for any one of the symbol data, wherein the set corresponding relation comprises a plurality of set symbols and a one-to-one correspondence relation of the set frequencies, symmetrically modulating the symbol data based on the set modulation frequencies and basic modulation frequencies to obtain symbol frequency characteristics corresponding to the symbol data, and controlling the rotating speed of the surface mounted motor to change along with the symbol frequency characteristics to generate modulated mud pulses. The application can realize the technical effects of improving the frequency offset resistance and the transmission rate, reducing the error rate and reducing the motor control difficulty.

Inventors

LUO MINGZHANG
KE LING
LI LEI
Lei Jingqiang
HEI CHUANG
ZHOU LUOYU
LIU ZHIYANG

Assignees

长江大学

Dates

Publication Date: 20260512
Application Date: 20260109

Claims (10)

1. The method for modulating the logging while drilling data code based on the mud pulse is characterized by being used for controlling a surface mounted motor to generate the mud pulse, and comprises the following steps of: Coding logging while drilling data to obtain code element data; for any code element data, acquiring a set modulation frequency corresponding to the code element data based on a set corresponding relation, wherein the set corresponding relation comprises a plurality of set code elements and a one-to-one corresponding relation of a plurality of set frequencies; And controlling the rotating speed of the surface-mounted motor to change along with the code element frequency characteristic to generate a modulated slurry pulse.
2. The mud pulse based code modulation for logging while drilling data of claim 1, wherein symmetrically modulating the symbol data based on the set modulation frequency and the base modulation frequency comprises: Based on the formula Symmetrically modulating the code element data; Wherein f i is the frequency of symbol data i, f i,min is the basic modulation frequency, f i,max is the set modulation frequency, T is the total modulation time, and T is the modulation time.
3. The mud pulse based logging while drilling data code modulation method of claim 1, further comprising: And acquiring a synchronous bit modulation frequency corresponding to the synchronous bit, and symmetrically modulating the synchronous bit based on the synchronous bit modulation frequency and a basic modulation frequency to obtain synchronous bit frequency characteristics corresponding to the synchronous bit.
4. The mud pulse based logging while drilling data code modulation method of claim 1, wherein said controlling the rotational speed of the surface mount motor as a function of the symbol frequency signature comprises: For any control moment, determining a control moment code element frequency corresponding to the control moment according to the code element frequency characteristic; Calculating according to a set constant and the control time code element frequency to obtain a target rotating speed; acquiring a control moment current and a control moment rotating speed of the surface mounted motor, and decoupling the control moment current to obtain a direct-axis current component and a quadrature-axis current component; determining a quadrature current compensation according to the control moment rotating speed and the target rotating speed, and integrating the quadrature current compensation and the quadrature current component to obtain a target quadrature current; And obtaining a target control current according to the direct-axis current component and the target quadrature-axis current, and controlling the rotating speed of the surface-mounted motor to change along with the code element frequency characteristic based on the target control current.
5. A mud pulse-based logging-while-drilling data code modulation device for controlling a surface mounted motor to generate mud pulses, the mud pulse-based logging-while-drilling data code modulation device comprising: The data coding module is used for coding logging while drilling data to obtain code element data; the frequency modulation module is used for acquiring set modulation frequency corresponding to the symbol data based on a set corresponding relation, wherein the set corresponding relation comprises a plurality of set symbols and a one-to-one corresponding relation of the set frequencies, and the symbol data is symmetrically modulated based on the set modulation frequency and a basic modulation frequency to obtain symbol frequency characteristics corresponding to the symbol data; and the motor control module is used for controlling the rotating speed of the surface-mounted motor to change along with the code element frequency characteristic so as to generate modulated mud pulse.
6. The method for coding and demodulating the logging-while-drilling data based on the mud pulse is characterized by comprising the following steps of: Acquiring actual mud pulse; window sampling is carried out on the actual mud pulse based on a set sampling window, so that a plurality of sampling mud pulses are obtained; Performing Fourier transform on each sampling mud pulse to obtain a signal peak frequency of the sampling mud pulse, and obtaining code element data corresponding to the signal peak frequency based on a set corresponding relation; and obtaining the demodulation logging while drilling data according to the code element data.
7. The mud pulse based code demodulation method for logging while drilling data of claim 6, wherein said fourier transforming each of said sampled mud pulses comprises: Based on the formula Performing Fourier transform on each sampling mud pulse; Wherein m is the time index of the sampling window, R is the moving step length of the sampling window, X (m, k) is the Fourier transform result at the time index m and the frequency index k, X [ n ] is the modulated mud pulse, w [ n ] MR is the window function of the sampling window, xn.wn MR is the sampling mud pulse, and N is the number of Fourier transform points.
8. The mud pulse based well logging while drilling data encoding and demodulation method of claim 6, further comprising: acquiring actual logging while drilling data, and training a neural network model by using the actual logging while drilling data, the demodulation logging while drilling data and the actual mud pulse until the training of the neural network model is completed; Demodulating the actual mud pulse based on the trained neural network model to obtain the demodulation logging while drilling data.
9. A mud pulse-based logging-while-drilling data encoding and demodulating device, comprising: The mud pulse acquisition module is used for acquiring modulated mud pulses; The window sampling module is used for performing window sampling on the modulated mud pulse based on a set sampling window to obtain a plurality of sampled mud pulses; The demodulation module is used for carrying out Fourier transformation on each sampling mud pulse to obtain the signal peak frequency of the sampling mud pulse, and acquiring code element data corresponding to the signal peak frequency based on a set corresponding relation; And the decoding module is used for obtaining the demodulation logging while drilling data according to the code element data.
10. A logging-while-drilling data transmission system, comprising: A data measuring device, a mud pulse-based logging-while-drilling data code modulation device, a surface mounted motor, a pulse acquisition device and a mud pulse-based logging-while-drilling data code demodulation device as defined in claim 5; The data measurement device collects logging while drilling data, the logging while drilling data code modulation device based on mud pulse executes the logging while drilling data code modulation method based on mud pulse according to any one of claims 1 to 4, the surface mounted motor is controlled to generate modulated mud pulse, the pulse collection device collects the actual mud pulse, and the logging while drilling data code demodulation device based on mud pulse executes the logging while drilling data code demodulation method based on mud pulse according to any one of claims 6 to 8 to demodulate the actual mud pulse to obtain demodulated logging while drilling data.

Description

Mud pulse-based logging-while-drilling data coding modulation and demodulation method and device Technical Field The application relates to the technical field of logging while drilling, in particular to a method and a device for coding and modulating logging while drilling data based on mud pulse, a method and a device for coding and demodulating logging while drilling data based on mud pulse, and a logging while drilling data transmission system. Background In real-time transmission of downhole data while drilling, the high cost of the compared with wired schemes, the susceptibility of acoustic waves to noise interference, electromagnetic waves to the formation, mud pulsing, by virtue of high reliability, long distance and economy, is the dominant application of downhole data transmission. The current main stream of slurry pulse application is divided into positive pulse and continuous wave pulse, wherein the positive pulse has good stability but low speed, and the continuous wave pulse has high-efficiency band-pass signal formed by modulation, so that the slurry pulse is an industrial standard. The performance of the continuous wave pulse depends on its modulation scheme, and typical modulation schemes include ASK (Amplitude SHIFT KEYING ), FSK (Frequency SHIFT KEYING, frequency shift keying), PSK (PHASE SHIFT KEYING ), and the like. However, ASK is easily affected by amplitude noise, so that the bit error rate is higher, PSK has good noise immunity, but is subject to engineering constraints such as high requirements on error rising and carrier synchronization caused by response delay and multipath effects of a mechanical valve body, FSK has strong amplitude noise resistance, excellent low signal to noise ratio performance, simple demodulation, low spectrum utilization rate and limited rate. Disclosure of Invention In view of the foregoing, it is necessary to provide a method and a device for modulating logging-while-drilling data based on mud pulse, a method and a device for demodulating logging-while-drilling data based on mud pulse, and a logging-while-drilling data transmission system for improving the frequency offset resistance and transmission rate, reducing the bit error rate, and reducing the difficulty of motor control. In order to solve the technical problem, in a first aspect, the present application provides a method for modulating logging while drilling data based on mud pulse, for controlling a surface mounted motor to generate mud pulse, the method for modulating logging while drilling data based on mud pulse comprises: Coding logging while drilling data to obtain code element data; for any one of the symbol data, acquiring a set modulation frequency corresponding to the symbol data based on a set correspondence, wherein the set correspondence comprises a one-to-one correspondence of a plurality of set symbols and a plurality of set frequencies, and symmetrically modulating the symbol data based on the set modulation frequency and a basic modulation frequency to obtain symbol frequency characteristics corresponding to the symbol data; And controlling the rotating speed of the surface-mounted motor to change along with the code element frequency characteristic to generate a modulated slurry pulse. In a possible embodiment, the symmetrically modulating the symbol data based on the set modulation frequency and the base modulation frequency includes: Based on the formula Symmetrically modulating the code element data; Wherein f i is the frequency of symbol data i, f i,min is the basic modulation frequency, f i,max is the set modulation frequency, T is the total modulation time, and T is the modulation time. In one possible embodiment, the method further comprises: And acquiring a synchronous bit modulation frequency corresponding to the synchronous bit, and symmetrically modulating the synchronous bit based on the synchronous bit modulation frequency and a basic modulation frequency to obtain synchronous bit frequency characteristics corresponding to the synchronous bit. In one possible embodiment, the controlling the rotation speed of the surface mount motor as a function of the symbol frequency characteristic includes: For any control moment, determining a control moment code element frequency corresponding to the control moment according to the code element frequency characteristic; Calculating according to a set constant and the control time code element frequency to obtain a target rotating speed; acquiring a control moment current and a control moment rotating speed of the surface mounted motor, and decoupling the control moment current to obtain a direct-axis current component and a quadrature-axis current component; determining a quadrature current compensation according to the control moment rotating speed and the target rotating speed, and integrating the quadrature current compensation and the quadrature current component to obtain a target quadrature current; And obtaining a targe