An intelligent multi-stage control method for oil well perforation firing

Abstract

This invention discloses an intelligent multi-level control method for perforation firing in oil wells, primarily addressing the problem of unstable data transmission in existing perforation firing control technologies. The method first requires creating a gun string, enabling the control system to communicate with each of the downhole multi-level electronic selectors to obtain the ID of each selector. After verification and inspection through the gun string, detonator checks and firing are performed. In the communication data transmission of this control method, this invention uses a fixed number of high-frequency signals within a fixed time period to represent high-level data 1, and then uses a fixed number of low-frequency signals within the same time period to represent low-level data 0. This method is suitable for single-core cable data communication in perforation firing, better adapting to the complex communication environment downhole, making data transmission communication in perforation firing control more reliable, faster, and more efficient.

Description

Technical Field

[0001] This invention belongs to the field of oil well perforation control technology, specifically, it relates to an intelligent multi-level control method for oil well perforation firing. Background Technology

[0002] Perforation is an operation that uses specialized shaped charge devices to explosively open holes in predetermined formations within a wellbore, allowing fluids from the formation to enter. It is widely used in oil and gas fields and coalfields, and sometimes in water extraction. For perforation to be detonated, a perforation selector is needed to control the firing. A perforation selector is a device that connects to a perforation projectile and detonates a detonator by sending high and low frequency pulse signals. This detonates the explosive charge inside the projectile, causing it to impact the wellbore wall and rock formation, creating a perforation channel. Multiple selectors can be connected in series in a string of guns and fired sequentially.

[0003] Perforation is a procedure performed before oil testing. The perforating gun is lowered to a predetermined depth, and the perforating springs propel the casing and cement sheath at the target formation, creating a connecting channel between the formation and the wellbore to facilitate oil and gas production operations.

[0004] With the increasing diversity of oil and gas reservoir development types both domestically and internationally, the difficulty of oilfield development is constantly increasing, placing higher demands on the development of supporting technologies. Perforation technology has gradually evolved from a single well completion method into a crucial link in the oil and gas reservoir development process. The main function of a multi-stage perforation control system is to complete the multi-stage firing control of the perforation firing plates throughout the entire downhole system. It can precisely control the firing operation of the firing plate at a specific position in the system's firing gun string. The perforation firing process requires data communication between the surface-to-well and downhole equipment. However, the surface-to-well and downhole equipment are connected by only a single-core cable, which can be several kilometers long. Furthermore, the downhole environment is extremely complex, resulting in significant errors in existing perforation firing control systems, making effective and reliable multi-stage perforation control impossible. Summary of the Invention

[0005] The purpose of this invention is to provide an intelligent multi-level control method for perforation firing in oil wells, which mainly solves the problem of unstable data transmission in perforation firing control in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for intelligent multi-stage control of oil well perforation firing includes the following steps:

[0008] S1, create a gun string, enabling the control system to communicate with each of the multi-level electronic selectors downhole and obtain the ID of each electronic selector;

[0009] S2, Gun string verification, compares the gun string ID data stored in the control system with the selector ID data actually connected downhole;

[0010] S3, Gun string check. After the gun string verification is completed, enter the gun string control interface to communicate with the downhole selector to determine whether the downhole selector is working properly.

[0011] S4, Detonator preparation, communicates with each level of electronic selector through the control system, and sets the lowest level electronic selector to the ready state;

[0012] S5, detonator firing, uses the control system to set the electronic selector to firing mode and enables manual firing.

[0013] Furthermore, in this invention, in step S1, the communication method between the control system and the electronic selector is as follows:

[0014] S11, Create a data packet consisting of four parts: data header, empty data, data content, and data trailer;

[0015] S12 uses high and low levels to represent the transmitted data. A fixed number of high-frequency signals are used within a fixed time period to represent high-level data 1, and a fixed number of low-frequency signals are used within the same time period to represent low-level data 0.

[0016] Furthermore, in this invention, all operation commands between the control system and the electronic selector are converted into electrical signals via digital signals and output as sine waves by the DAC. The sine waves are amplified by the amplifier in the encoding and transmitting module of the control system and sent to the electronic selector downhole, where they are decoded.

[0017] Furthermore, the present invention also includes superimposing a decoding sensitivity control voltage on a single-core cable that serves as the communication medium between the control system and the electronic selector.

[0018] Furthermore, in step S11, the data header consists of a set of high-frequency signals with a fixed frequency, and a low-level signal with the same duration as the high and low frequency signals is appended after the data header as empty data.

[0019] Furthermore, the verification can only be successful if the ID in the gun string data in the control system corresponds one-to-one with the ID of the electronic selector actually connected downhole. Otherwise, the verification will fail and the gun string will not be able to complete the firing operation. During the verification period, all electronic selectors that have been fired or skipped firing will not be verified.

[0020] Furthermore, in step S5, after the electronic selector is set to the firing state by the control system, the control system will display the real-time voltage and current status of the electronic selector. At this time, the operator needs to manually apply a voltage greater than 60V to the selector within a set time. The detonator will only start detonating after the selector detects this voltage. If the operator fails to apply a voltage greater than 60V within the specified time, the control system will automatically shut off the power supply to the selector.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The perforation firing control method of this invention first requires creating a gun string, allowing the control system to communicate with each of the multi-stage electronic selectors downhole to obtain the ID of each electronic selector. After verification and inspection through the gun string, detonator checks and firing are performed. In the communication data transmission of this control method, this invention uses a fixed number of high-frequency signals within a fixed time period to represent high-level data 1, and then uses a fixed number of low-frequency signals within the same time period to represent low-level data 0. This method is suitable for single-core cable data communication in perforation firing, and is more adaptable to the complex communication environment downhole, making data transmission communication in perforation firing control more reliable, faster, and more efficient. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the control flow of the method of the present invention. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments.

[0025] like Figure 1 As shown, the present invention discloses an intelligent multi-stage control method for oil well perforation firing, comprising the following steps:

[0026] S1, Create a firing string. Before firing the electronic selector in stages, the first thing to do is to create a firing string. The main purpose of creating a firing string is to communicate with each of the multi-stage electronic selectors downhole, to ensure that all electronic selectors connected to the line are working properly, and to obtain the ID of each electronic selector.

[0027] S2, Gun String Verification: To fire the electronic selector on the gun string, the gun string needs to be verified. The gun string to be verified can be a newly created gun string or an existing gun string. The gun string verification process is to compare the gun string ID data with the actual selector ID data connected downhole. Only when the ID in the gun string data corresponds one-to-one with the ID of the actual selector connected downhole can the verification be successful, and the next step can be carried out. Otherwise, the verification fails, and the gun string cannot complete the firing operation. During the verification period, all selectors that have been fired or skipped firing will not be verified.

[0028] S3, Detonator String Check: After the detonator string has completed its verification process, a successfully verified string can enter the detonator string control interface for pre-firing preparations. The detonator string check is one such process, its main purpose being to communicate with the downhole selector to determine if the selector is functioning correctly. If all selectors are functioning correctly, detonator preparation can proceed.

[0029] S4, Detonator Preparation, also requires communication with each level of electronic selector to set the lowest level electronic selector to the ready state. Only selectors in the ready state can perform detonator firing.

[0030] S5, Detonator Activation: For operational safety, detonator activation is semi-automatic. First, the software sets the electronic selector to firing mode. The software will then display the real-time voltage and current status of the selector. The operator must manually apply a voltage greater than 60V to the selector within a set time. The detonator will only detonate after detecting this voltage. If the operator fails to apply a voltage greater than 60V within the specified time, the software will automatically shut off the selector's power supply. This ensures safe operation and prevents misoperation.

[0031] Since various operations require data communication between equipment above and below ground, and this connection relies solely on a single-core cable that can be several kilometers long, coupled with the complex environment underground, this embodiment improves the data transmission method. In this communication method, a data packet is first established, consisting of a data header, empty data, data content, and a data tail. The data header comprises a set of high-frequency signals at a fixed frequency, followed by a low-level signal of the same duration as the high and low-frequency signals, serving as empty data. Furthermore, due to the unique communication environment, the data content of each data packet is very short, at most four bytes, thus each data packet represents a complete communication instruction.

[0032] Because the communication medium is a single-core cable, data can only be represented by high and low voltage levels. Due to the strong interference underground, using a single high or low voltage level to represent 1 or 0 is obviously unreliable. After multiple theoretical calculations and actual tests, this invention adopts a method of using a fixed number of high-frequency signals (5.2K frequency as high-frequency modulation signal) to represent data 1 within a fixed time period, and then using a fixed number of low-frequency signals (2.5K frequency as low-frequency modulation signal) to represent data 0 within the same time period. This ensures reliable, fast, and efficient data transmission.

[0033] Regarding the aforementioned data encoding and transmission method, during actual testing, it was found that as the number of electronic selectors connected in series on the downhole gun string increased, the current in the single-core cable increased, and the communication signal tended to saturate, significantly affecting the originally smooth communication. Therefore, this invention chooses to superimpose a decoding sensitivity control voltage on the single-core cable. Its main function is to superimpose the voltage output from the DACout terminal with the original voltage on the single-core cable. If the number of electronic selectors connected in series on the downhole gun string increases, the output voltage of this decoding sensitivity also increases accordingly, thus strengthening the signal transmitted on the cable. This better ensures the correct signal transmission when there are many selectors connected in series on the gun string. When there are fewer selectors connected in series on the gun string, the output voltage of this module is reduced accordingly, keeping the transmitted signal on the cable at a relatively stable level, thereby greatly improving the communication capability of data in harsh environments, over long distances, and under different load conditions.

[0034] The control method of this invention first requires creating a gun string. If a valid, already created gun string exists, it can be selected directly. Then, the gun string needs to be verified. Only after successful verification can the control interface be accessed. Upon entering the control interface, the first step is to check the gun string, followed by detonator preparation. After detonator preparation, the topmost firing selector is activated, allowing for gun skipping and firing operations. If a gun skip command is executed, the currently active firing selector will be skipped, and it will be unable to fire again during subsequent firing processes. After gun skipping, the power supply to the entire gun string will automatically disconnect, requiring a re-check of the gun string and detonator preparation, followed by another selection of gun skipping or firing. If firing is selected, a V / I curve interface will immediately pop up (its main function is to display the collected real-time firing voltage and current on a curve, determining firing success based on the firing current). Within a certain timeframe, the operator needs to manually power on the detonator to bring the firing voltage to the firing threshold, thereby triggering the selector to detonate the detonator. After the operation is completed, the power to the firing pin will be automatically cut off again. At this time, the firing pin needs to be checked and the detonators prepared, and then the firing pin or firing operation needs to be completed again, until all the selectors on the firing pin have been skipped or fired. At this time, a complete firing operation is completed.

[0035] Through the above design, the communication data transmission of the control method of the present invention is more suitable for single-core cable data communication in perforation firing, and is more adaptable to the complex communication environment downhole, making data transmission communication in perforation firing control more reliable, faster, and more efficient. Therefore, it is suitable for widespread application.

[0036] The above embodiments are merely one of the preferred embodiments of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but solve the same technical problem as the present invention, should be included within the scope of protection of the present invention.

Claims

1. A method for intelligent multi-level control of oil well perforation firing, characterized in that, Includes the following steps: S1, create a gun string to enable the control system to communicate with each of the multi-stage electronic selectors downhole, obtain the ID of each electronic selector, and superimpose a decoding sensitivity control voltage on the single-core cable that serves as the communication medium between the control system and the electronic selectors; the communication method between the control system and the electronic selectors is as follows: S11, Create a data packet consisting of four parts: data header, empty data, data content, and data trailer; S12 uses high and low levels to represent transmitted data. A fixed number of high-frequency signals are used within a fixed time period to represent high-level data 1, and a fixed number of low-frequency signals are used within the same time period to represent low-level data 0. S2, Gun string verification, compares the gun string ID data stored in the control system with the selector ID data actually connected downhole; S3, Gun string check. After the gun string is checked, enter the gun string control interface to communicate with the downhole selector to determine whether the downhole selector is working properly. S4, Detonator preparation, communicates with each level of electronic selector through the control system, and sets the lowest level electronic selector to the ready state; S5, detonator firing, uses the control system to set the electronic selector to firing mode and enables manual firing.

2. The intelligent multi-level control method for oil well perforation firing according to claim 1, characterized in that, All operating commands between the control system and the electronic selector are converted into electrical signals via digital signals and output as sine waves by the DAC. The sine waves are amplified by the amplifier in the encoding and transmitting module of the control system and sent to the electronic selector downhole, where they are decoded.

3. The intelligent multi-level control method for oil well perforation firing according to claim 2, characterized in that, In step S11, the data header consists of a set of high-frequency signals with a fixed frequency, and a low-level signal with the same duration as the high and low frequency signals is followed by the data header as empty data.

4. The intelligent multi-stage control method for oil well perforation firing according to claim 3, characterized in that, In step S2, the verification can only be successful if the ID in the gun string data in the control system corresponds one-to-one with the ID of the electronic selector actually connected downhole, thus enabling gun string inspection. Otherwise, the verification fails and the gun string cannot complete the firing operation. During the verification period, all electronic selectors that have already fired or skipped firing will not be verified.

5. The intelligent multi-level control method for oil well perforation firing according to claim 4, characterized in that, In step S5, after the electronic selector is set to the firing state by the control system, the control system will display the real-time voltage and current status of the electronic selector. At this time, the operator needs to manually apply a voltage greater than 60V to the selector within the set time. The detonator will only start detonating after the selector detects this voltage. If the operator fails to apply a voltage greater than 60V within the specified time, the control system will automatically shut off the power supply to the selector.

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