A micro-columnar resistivity focusing system and control method thereof

Abstract

The present invention discloses a micro-columnar resistivity focusing system and its control method. The system includes a DSP microprocessor, a two-channel D / A converter, a two-channel power amplifier, a micro-columnar focusing plate, a focusing controller, a multiplexer, and an A / D converter. The disclosed micro-columnar resistivity focusing system utilizes a DSP-controlled soft and hard dual-drive focusing circuit system, enabling simultaneous focusing in both longitudinal and transverse directions. This solves the problem of inaccurate resistivity measurements in flushing zones caused by current divergence, meets the requirements for resistivity measurements in flushing zones with complex lithologies, thin layers, and thin interbedded layers, and is highly beneficial for permeability formation evaluation.

Description

Technical Field

[0001] The invention belongs to the field of resistivity logging, and in particular relates to a micro-columnar resistivity focusing system and a control method thereof in the field. Background Art

[0002] The Micro-Cylindrical Resistivity Log (MCFL) is a shallow-probe resistivity logging instrument used to replace micro-sphere focused logging tools. It measures the resistivity (Rxo) of the flushing zone, improving its accuracy and estimating mudcake parameters, thus facilitating the detection of permeable formations. It also provides two synthetic microelectrode curves through inversion. Traditional focusing systems and control methods, however, can only focus in a single direction, either vertically or horizontally. They cannot simultaneously control both vertical and horizontal focusing, resulting in current divergence and making it difficult to accurately detect flushing zone resistivity. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a novel micro-columnar resistivity focusing system and a control method thereof.

[0004] The present invention adopts the following technical solutions:

[0005] A micro-columnar resistivity focusing system is improved in that it includes a DSP microprocessor, two-way DA converters, two-way power amplifiers, a micro-columnar focusing plate, a focusing controller, a multiplexer, and an AD converter, wherein the micro-columnar focusing plate includes an A0 electrode, two A1 electrodes, a VV electrode, a B0 electrode, a B1 electrode, a B2 electrode, and two M electrodes; the DSP microprocessor is electrically connected to the A0 electrode and the A1 electrode respectively through a DA converter and a power amplifier; the B0 electrode, the B1 electrode, and the B2 electrode are all electrically connected to the focusing controller; the two-way power amplifiers, the A0 electrode, the VV electrode, the focusing controller, and the M electrodes are all electrically connected to the multiplexer; and the multiplexer is electrically connected to the DSP microprocessor through the AD converter.

[0006] Furthermore, the A0 electrode is in an "I-shape" and is the main emitting electrode. The A1 electrode is a longitudinal shielding electrode. The two A1 electrodes are symmetrically arranged on the upper and lower sides of the A0 electrode. The M electrode is a monitoring electrode. The two M electrodes are respectively arranged between the A0 electrode and the two A1 electrodes. The B0 electrode, B1 electrode and B2 electrode are emitting button electrodes. The three emitting button electrodes are horizontally aligned and arranged in the middle of the A0 electrode. The VV electrode is a reference electrode and is arranged outside the A0 electrode.

[0007] A control method is applicable to the above-mentioned micro-columnar resistivity focusing system, wherein the improvement is that the control method comprises the following steps:

[0008] Longitudinal focus drive: The DSP microprocessor calculates a digital sine wave with a specific frequency and correct amplitude, converts it into an analog signal through two DA converters, and then passes through the corresponding two power amplifiers to generate a 1A current and transmit it to the A0 electrode and the A1 electrode respectively, and the potential difference V between the monitoring electrode M and the A0 electrode is M –V A0 , A0 electrode output current I A0 and A1 electrode output current I A1 Send to multiplexer;

[0009] Horizontal focusing drive: It is completed by three focusing controllers. The focusing controller keeps the transmitting button electrodes B0, B1, B2 at the same potential as the A0 electrode to achieve lateral current focusing. At the same time, the focusing controller converts the voltage in the transmitting button electrode into a current I b0 , I b1 , I b2 , and sent to the multiplexer;

[0010] The multiplexer converts the voltage V A0 , the voltage of VV electrode V A0 -V vv The signals are sent to the AD converter together with the other signals sent above to be converted into digital signals and then sent to the DSP microprocessor for processing;

[0011] The DSP microprocessor connects I A0 and I A1 The amplitudes of the in-phase and quadrature parts of the waveform are calculated by multiplying them by the reference cosine and sine tables and taking the average value. Phase shift is applied to all signals, the signal amplitude is determined, and the output amplitude of the voltage of the A0 electrode and the A1 electrode is adjusted so that the potential difference between the monitoring electrode M and the A0 electrode is |V M –V A0 |=0, and keep the current I in the button electrode b0 , I b1 and I b2 Limit to a minimum or maximum range.

[0012] Furthermore, the entire adjustment process is at a rate of 120 Hz. If I b0 If it is lower than the predefined lower limit, V A0 Increase by 5% if I b0 , I b1 or I b2 If any of the above conditions is higher than the predefined upper limit, it will be reduced by 50%. If neither of the two conditions is met, V A0 unchanged, by controlling V A1 The amplitude of the in-phase and quadrature parts of the monitoring electrode M and the A0 electrode is driven to zero, |V M –VA0 |=0, use two coefficients alpha_P and alpha_Q:

[0013] V A1 P=alpha_P×V A0

[0014] V A1 Q=alpha_Q×V A0

[0015] The monitoring loop algorithm adjusts alpha_P and alpha_Q via proportional feedback: If V M –V A0 If the in-phase part of V is positive, then reduce alpha_P, if it is negative, then increase alpha_P. M –V A0 The orthogonal part of α is adjusted using the same adjustment method.

[0016] Furthermore, the resistivity values ​​at different incident depths are obtained by the following formula:

[0017]

[0018]

[0019]

[0020] In the above formula, k0, k1, and k2 represent geometric factors of different intrusion depths.

[0021] The beneficial effects of the present invention are:

[0022] The micro-columnar resistivity focusing system disclosed in the present invention is a soft and hard dual-drive focusing circuit system based on DSP control. It takes into account simultaneous focusing in both vertical and horizontal directions, solves the problem of inaccurate resistivity measurement in flushing zones caused by current divergence, meets the resistivity measurement needs of flushing zones with complex lithology, thin layers, and thin interbeds, and is very helpful for permeability formation evaluation.

[0023] The control method disclosed in the present invention is used to control the micro-columnar resistivity focusing system of the present invention, which is beneficial to the performance of the micro-columnar resistivity focusing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a block diagram of the composition of the micro-columnar resistivity focusing system disclosed in the present invention;

[0025] Figure 2 It is a schematic structural diagram of a micro-columnar focusing plate in the micro-columnar resistivity focusing system disclosed in the present invention;

[0026] Figure 3It is a circuit diagram of a focusing controller in the micro-columnar resistivity focusing system disclosed in the present invention;

[0027] Figure 4 It is a flow chart of the control method disclosed in the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] Example 1: This example discloses a micro-columnar resistivity focusing system, such as Figure 1 As shown, it includes a DSP microprocessor 1, two high-precision DA converters 2, two power amplifiers 3, vertical and horizontal bidirectional micro-cylindrical focusing plates 4, a focusing controller 5, a multiplexer 6 and an AD converter 7, wherein the micro-cylindrical focusing plates include an A0 electrode, two A1 electrodes, a VV electrode, a B0 electrode, a B1 electrode, a B2 electrode and two M electrodes. The DSP microprocessor is electrically connected to the A0 electrode and the A1 electrode through a DA converter and a power amplifier respectively, the B0 electrode, the B1 electrode and the B2 electrode are all electrically connected to the focusing controller, the two power amplifiers, the A0 electrode, the VV electrode, the focusing controller and the M electrodes are all electrically connected to the multiplexer, and the multiplexer is electrically connected to the DSP microprocessor through the AD converter.

[0030] like Figure 2 As shown, the micro-cylindrical focusing plates are arranged in both vertical and horizontal directions. The A0 electrode is in an "I-shape" and is the main emitting electrode. The A1 electrode is a longitudinal shielding electrode. The two A1 electrodes are symmetrically arranged on the upper and lower sides of the A0 electrode. The M electrode is a monitoring electrode. The two M electrodes are respectively arranged between the A0 electrode and the two A1 electrodes. The B0 electrode, B1 electrode and B2 electrode are emitting button electrodes. The three emitting button electrodes are aligned horizontally and arranged in the middle of the A0 electrode. The specific positions and sizes of the three emitting button electrodes are set according to different current incidence depths. The VV electrode is a reference electrode and is arranged outside the A0 electrode.

[0031] Figure 3 This is a circuit diagram of a focus controller, which has very low input impedance.

[0032] The micro-columnar resistivity focusing system disclosed in this embodiment utilizes a DSP-controlled, dual-drive focusing circuit system and control method based on soft and hard focusing, combining the characteristics of micro-columnar focusing plates. Vertical focusing is driven by DSP+DAC software. By adjusting the drive current between the transmitting and shielding electrodes, monitoring the potential difference between the monitoring electrodes, and dynamically adjusting the output current in real time, the vertical current is focused into the formation. The horizontal focusing system is driven by a hardware controller to ensure that the lateral current is focused into the formation. A specific calculation method is used to obtain resistivity values ​​at different depths of incidence, thereby reflecting the formation intrusion relationship and response characteristics.

[0033] This embodiment also discloses a control method applicable to the above-mentioned micro-columnar resistivity focusing system, such as Figure 4 As shown, the following steps are included:

[0034] Longitudinal focus drive: The DSP microprocessor calculates a digital sine wave with a frequency of 1kHz and correct amplitude, converts it into an analog signal through two 16-bit DA converters, and then passes through the corresponding two power amplifiers to generate an adjustable current of up to 1A and transmit it to the A0 electrode and the A1 electrode, respectively, to monitor the potential difference V between the electrode M and the A0 electrode. M –V A0 , A0 electrode output current I A0 and A1 electrode output current I A1 Send to multiplexer;

[0035] Horizontal focusing drive: It is completed by three focusing controllers. The focusing controller has a very low input impedance and combines the "virtual off" characteristics of the operational amplifier to keep the transmitting button electrodes B0, B1, B2 at the same potential as the A0 electrode to achieve lateral current focusing. At the same time, the focusing controller converts the voltage in the transmitting button electrode into a current I b0 , I b1 , I b2 , and sent to the multiplexer;

[0036] The multiplexer converts the voltage V A0 , the voltage of VV electrode V A0 -V vv The signals are sent to the AD converter together with the other signals sent above to be converted into digital signals and then sent to the DSP microprocessor for processing;

[0037] The DSP microprocessor connects I A0 and I A1The amplitudes of the in-phase and quadrature portions of the waveform are calculated by multiplying by reference cosine and sine tables and taking the average value. This is called digital DPSD (digital phase sensitive detection) processing. After PSD processing, a phase shift is applied to all signals that is equal to the inverse of the phase of the A0 electrode current. Therefore, the phase of the composite signal is always I A0 By this way, the signal amplitude is determined and the output amplitude of the voltage of the A0 electrode and the A1 electrode is adjusted so that the potential difference between the monitoring electrode M and the A0 electrode |V M –V A0 |=0, and keep the current I in the button electrode b0 , I b1 and I b2 Limit to a minimum or maximum range.

[0038] The entire adjustment process is at a rate of 120Hz. If I b0 If it is lower than the predefined lower limit, V A0 Increase by 5% if I b0 , I b1 or I b2 If any of the above conditions is higher than the predefined upper limit, it will be reduced by 50%. If neither of the two conditions is met, V A0 unchanged, by controlling V A1 The amplitude of the in-phase and quadrature parts of the monitoring electrode M and the A0 electrode is driven to zero, |V M –V A0 |=0, use two coefficients alpha_P and alpha_Q:

[0039] V A1 P=alpha_P×V A0

[0040] V A1 Q=alpha_Q×V A0

[0041] The monitoring loop algorithm adjusts alpha_P and alpha_Q via proportional feedback: If V M –V A0 If the in-phase part of V is positive, then reduce alpha_P, if it is negative, then increase alpha_P. M –V A0 The orthogonal part of α is adjusted using the same adjustment method.

[0042] The resistivity values ​​at different incident depths are obtained by the following formula:

[0043]

[0044]

[0045]

[0046] In the above formula, k0, k1, and k2 represent geometric factors of different intrusion depths.

Claims

1. A micro-columnar resistivity focusing system, characterized by: The invention comprises a DSP microprocessor, a two-channel DA converter, a two-channel power amplifier, a micro-cylindrical focusing plate, a focusing controller, a multiplexer and an AD converter, wherein the micro-cylindrical focusing plate comprises an A0 electrode, two A1 electrodes, a VV electrode, a B0 electrode, a B1 electrode, a B2 electrode and two M electrodes; the DSP microprocessor is electrically connected to the A0 electrode and the A1 electrode respectively through a DA converter and a power amplifier; the B0 electrode, the B1 electrode and the B2 electrode are all electrically connected to the focusing controller; the two-channel power amplifier, the A0 electrode, the VV electrode, the focusing controller and the M electrodes are all electrically connected to the multiplexer; and the multiplexer is electrically connected to the DSP microprocessor through the AD converter.

2. The micro-columnar resistivity focusing system according to claim 1, characterized in that: The A0 electrode is in an "I-shape" and is the main emitting electrode. The A1 electrode is a longitudinal shielding electrode. The two A1 electrodes are symmetrically arranged on the upper and lower sides of the A0 electrode. The M electrode is a monitoring electrode. The two M electrodes are respectively arranged between the A0 electrode and the two A1 electrodes. The B0 electrode, B1 electrode and B2 electrode are emitting button electrodes. The three emitting button electrodes are horizontally aligned and arranged in the middle of the A0 electrode. The VV electrode is the reference electrode and is arranged outside the A0 electrode.

3. A control method, applicable to the micro-columnar resistivity focusing system according to claim 2, characterized in that: The steps include: Longitudinal focus drive: The DSP microprocessor calculates a digital sine wave with a specific frequency and correct amplitude, converts it into an analog signal through two DA converters, and then passes through the corresponding two power amplifiers to generate a 1A current and transmit it to the A0 electrode and the A1 electrode respectively, and the potential difference V between the monitoring electrode M and the A0 electrode is M –V A0 , A0 electrode output current I A0 and A1 electrode output current I A1 Send to multiplexer; Horizontal focusing drive: It is completed by three focusing controllers. The focusing controller keeps the transmitting button electrodes B0, B1, B2 at the same potential as the A0 electrode to achieve lateral current focusing. At the same time, the focusing controller converts the voltage in the transmitting button electrode into a current I b0 , I b1 , I b2 , and sent to the multiplexer; The multiplexer converts the voltage V A0 , the voltage of VV electrode V A0 -V vv And the potential difference V between the monitoring electrode M and the A0 electrode M –V A0 , A0 electrode output current I A0 and A1 electrode output current I A1 , current I b0 , I b1 , I b2 The signals are sent to AD converter together and converted into digital signals and then sent to DSP microprocessor for processing; The DSP microprocessor connects I A0 and I A1 Multiply by the reference cosine and sine tables and take the average to calculate I A0 and I A1 The amplitude of the in-phase and quadrature parts of the waveform, apply phase shift to all signals, determine the signal amplitude and adjust the output amplitude of the voltage of the A0 electrode and the A1 electrode so that the potential difference between the monitoring electrode M and the A0 electrode |V M –V A0 |=0, and keep the current I in the button electrode b0 , I b1 and I b2 Limit to a minimum or maximum range.

4. The control method according to claim 3, wherein: The entire adjustment process is at a rate of 120 Hz. If I b0 If it is lower than the predefined lower limit, V A0 Increase by 5%, if I b0 , I b1 or I b2 If any of the above conditions is higher than the predefined upper limit, it will be reduced by 50%. If neither of the two conditions is met, V A0 unchanged, by controlling V A1 The amplitude of the in-phase and quadrature parts of the monitoring electrode M and the A0 electrode is driven to zero, |V M –V A0 |=0, using two coefficients alpha_P and alpha_Q: ； ； The monitoring loop algorithm adjusts alpha_P and alpha_Q via proportional feedback: If V M –V A0 If the in-phase part of V is positive, then reduce alpha_P, if it is negative, then increase alpha_P. M –V A0 The orthogonal part of α is adjusted using the same adjustment method.

5. The control method according to claim 3, wherein: The resistivity values ​​at different incident depths are obtained by the following formula: ； ； ； In the above formula, k0, k1, and k2 represent geometric factors of different intrusion depths.

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