Digital bridge plug and hydraulic fracturing inter-segment packing and pressure measuring integrated method

Abstract

The invention belongs to the technical field of hydraulic fracturing, and discloses a digital bridge plug and a hydraulic fracturing inter-section packing and pressure measuring integrated method. The digital bridge plug comprises a bridge plug, wherein a pressure sensor and a power supply for supplying power to the pressure sensor are arranged in the bridge plug; the pressure sensor comprises a pressure testing unit and a signal transmission unit which are connected; and the signal transmission unit is in signal connection with a ground signal receiving device arranged at a wellhead. The method comprises the steps that firstly, after hydraulic fracturing of the previous section of a shaft is completed, a power source of a pressure sensor is turned on, and the digital bridge plug is pumped into the section design position between the previous section and the next section of the shaft through a cable pump; secondly, after the digital bridge plug is set, the digital bridge plug expands to conduct inter-section packing; after the digital bridge plug enters a shaft, the pressure sensor measures the bottom hole pressure in real time and transmits the bottom hole pressure to the ground signal receiving device. The fracturing effect can be evaluated more accurately through well bottom pressure data monitored in real time.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic fracturing technology and relates to a digital bridge plug and an integrated method for sealing and pressure measurement between hydraulic fracturing sections. Background Technology

[0002] Horizontal well staged fracturing technology, as a key means of enhancing oil and gas recovery in modern oil and gas field development, focuses on precisely controlling the stress state of the formation surrounding the wellbore to induce a fracture network, thereby increasing oil and gas flow channels and improving reservoir permeability. In this process, accurate monitoring and recording of bottom-hole pressure data plays an irreplaceable role in accurately analyzing and evaluating the fracturing effect. First, bottom-hole pressure data directly reflects the dynamic changes when fracturing fluid is injected into the formation, including pressure rise rate, peak pressure, and pressure fluctuations. This information is crucial for determining the initiation, propagation direction, and morphology of fractures. By monitoring bottom-hole pressure in real time, technicians can adjust pumping parameters such as flow rate, pressure, and shutdown time to optimize the fracture network distribution and ensure maximum fracturing effect. Second, bottom-hole pressure data can also be used to assess formation characteristics, such as rock strength, stress distribution, and the development of natural fractures. These parameters are essential for designing a reasonable fracturing scheme. For example, high pressure peaks may indicate the encounter with strong rock layers, requiring increased fracturing fluid pressure or changes in the fracturing fluid formulation to overcome this obstacle. Pressure fluctuations, on the other hand, may suggest the presence of natural fractures or faults in the formation; effectively utilizing these natural structures can significantly improve fracturing efficiency. Furthermore, bottom-hole pressure data can be used to assess the safety and efficiency of fracturing operations. Excessively high bottom-hole pressure may trigger formation fracturing, leading to wellbore instability or fluid leakage, while excessively low pressure may prevent the effective formation of a fracture network, reducing fracturing effectiveness. Therefore, by monitoring and analyzing bottom-hole pressure data in real time, technicians can promptly identify and address potential operational risks, ensuring the safe and smooth progress of fracturing operations. Finally, bottom-hole pressure data is also an important reference for assessing the production capacity of oil and gas wells after fracturing. The trend of bottom-hole pressure changes after fracturing can indirectly reflect the degree of improvement in reservoir permeability, thereby predicting the production potential of oil and gas wells. Comprehensive analysis combined with production data can provide strong support for subsequent adjustments and optimizations to development plans.

[0003] However, in horizontal well bare casing fracturing mode, since there is no working string in the wellbore, it is impossible to carry a downhole pressure gauge into the well, making it very difficult to obtain this data. Currently, there are only two ways to obtain bottom hole pressure data in horizontal well bare casing fracturing mode: The first is to add the wellbore fluid column pressure to the surface data recorded by the fracturing equipment during fracturing, and then subtract the friction loss. The advantage of this method is its simple calculation process, but its limitation is that the friction loss in the wellbore during fracturing is frequently affected by the performance and flow rate of the fracturing fluid, making it impossible to obtain accurate friction loss data. Therefore, the bottom hole pressure obtained by this method has poor accuracy, which to some extent affects the accuracy of the analysis results. The second method is to obtain the bottom hole pressure by running a permanent external fiber optic cable with a pressure gauge along with the casing during the casing running process after the horizontal well is completed. The advantage of this method is that it can accurately monitor the bottom hole pressure data throughout the entire fracturing stage and the entire life cycle of production. The limitation is that the cost of using external fiber optic cable to monitor bottom hole pressure data is high, with the cost of monitoring and interpretation for a single horizontal well exceeding two million yuan, making it difficult to achieve large-scale application. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems of inaccurate methods for obtaining bottom hole pressure during horizontal fracturing and high equipment costs in the prior art, and to provide a digital bridge plug and an integrated method for sealing and measuring pressure between hydraulic fracturing sections.

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

[0006] In a first aspect, the present invention provides a digital bridge plug, comprising a bridge plug, wherein a pressure sensor and a power supply for supplying power to the pressure sensor are disposed in the bridge plug; the pressure sensor includes a pressure testing unit and a signal transmission unit connected thereto; the signal transmission unit is signal-connected to a surface signal receiving device disposed at the wellhead.

[0007] Further improvements are made in the following aspects:

[0008] The pressure testing unit includes an upper probe located at the top of the bridge plug and a lower probe located at the bottom of the bridge plug.

[0009] The upper probe includes several pressure contacts arranged in a ring on the top of the bridge plug; the lower probe includes several pressure contacts arranged in a ring on the bottom of the bridge plug.

[0010] The upper probe includes six pressure contacts arranged in a ring at 60° intervals on the top of the bridge plug; the lower probe includes four pressure contacts arranged in a ring at 90° intervals on the bottom of the bridge plug.

[0011] The pressure contact is equipped with a sand shield.

[0012] The signal transmission unit uses pulse signals to transmit data to the ground signal receiving device.

[0013] Secondly, the present invention provides an integrated method for hydraulic fracturing inter-stage isolation and pressure measurement using the aforementioned digital bridge plug, comprising:

[0014] Step 1: After the hydraulic fracturing of the upper section of the wellbore is completed, turn on the power to the pressure sensor and use a cable pump to send the digital bridge plug to the designed position between the upper and lower sections of the wellbore.

[0015] Step two: After the digital bridge plug is set, it expands to seal between sections, and then hydraulic fracturing continues in the next section; after the digital bridge plug enters the wellbore, the pressure sensor measures the bottom hole pressure in real time and transmits it to the surface signal receiving device to complete the hydraulic fracturing section sealing and pressure measurement.

[0016] Further improvements are made in the following aspects:

[0017] After receiving the signal, the ground signal receiving device converts it into well bottom pressure data for reading and storage.

[0018] The net pressure during the hydraulic fracturing process is calculated based on the bottom hole pressure data, and a double logarithmic curve of net pressure versus time is plotted.

[0019] The inter-segment design location is the middle position between the upper and lower sections of the wellbore during hydraulic fracturing.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention discloses a digital bridge plug with a built-in pressure sensor that can acquire and transmit bottomhole pressure data in real time. This allows surface operators to monitor pressure changes during fracturing, enabling more precise fracturing control and adjustments. This helps improve the efficiency of fracturing operations and reduces potential problems caused by improper pressure control. Furthermore, the pressure sensor can be turned off before entering the well and activated just before entry, effectively avoiding unnecessary wear and tear and the risk of misoperation during transportation and installation, thus enhancing overall operational safety. Real-time monitoring of bottomhole pressure data allows for more accurate evaluation of fracturing effectiveness and timely adjustment of fracturing parameters, such as fracturing fluid injection rate and pressure, to achieve optimal fracturing results and improve oil and gas well production efficiency.

[0022] Furthermore, the pressure testing unit includes an upper probe positioned at the top of the bridge plug and a lower probe positioned at the bottom of the bridge plug, respectively monitoring pressure changes at the top and bottom of the bridge plug. This not only covers a wider pressure monitoring range but also improves data accuracy and reliability through multi-point sampling. Even if some probes are buried in sand, other contacts can continue to operate, ensuring data continuity and integrity. Sand guards are also installed on the outside of the pressure contacts to protect them.

[0023] This invention discloses an integrated method for inter-stage isolation and pressure measurement in hydraulic fracturing. During the hydraulic fracturing process, a digital bridge plug is installed in the middle of each wellbore segment. After the first segment is fracturing, the digital bridge plug is lowered into the middle position between the first and second segments using a cable pump. After the digital bridge plug sets, its rubber sleeve expands to achieve inter-stage isolation. Then, hydraulic fracturing is performed on the second segment, and the process is repeated until the entire well is hydraulically fracturing is completed. This method integrates inter-stage isolation and real-time pressure measurement during the hydraulic fracturing process.

[0024] Furthermore, after receiving the signal, the ground signal receiving device converts it into bottom hole pressure data for reading and storage. Based on the bottom hole pressure data, the net pressure during the hydraulic fracturing process is calculated, and a double logarithmic curve of net pressure versus time is plotted. The double logarithmic curve can more intuitively show whether the fracture height is always under control during the artificial fracture propagation process and whether the fracture mainly extends within the reservoir. This allows for a more accurate assessment of the fracturing effect and timely adjustment of fracturing parameters, such as fracturing fluid injection rate and pressure, to achieve the best fracturing effect and improve the production efficiency and output of oil and gas wells. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram illustrating the operation of an integrated method for sealing and pressure measurement between hydraulic fracturing sections in this invention.

[0027] Figure 2 This is a schematic diagram of the top surface of the digital bridge plug in this invention.

[0028] The components are: 1-Ground signal receiving device; 2-Well shaft; 3-Artificial crack; 4-Digital bridge plug; 5-Sealing sleeve; 6-Pressure sensor; 7-Battery; 8-Top surface of digital bridge plug; 9-Upper probe; 10-Pressure contact; 11-Deployment tool interface. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0031] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0032] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0033] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0034] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0035] The present invention will now be described in further detail with reference to the accompanying drawings:

[0036] See Figure 1 and Figure 2 This invention discloses a digital bridge plug, comprising a bridge plug, a pressure sensor 6 and a power supply 7 for powering the pressure sensor 6. The pressure sensor 6 includes a pressure testing unit and a signal transmission unit connected together. The pressure testing unit includes an upper probe at the top of the bridge plug and a lower probe at the bottom of the bridge plug. The upper probe includes several pressure contacts arranged in a ring at the top of the bridge plug; the lower probe includes several pressure contacts arranged in a ring at the bottom of the bridge plug. The upper probe includes six pressure contacts arranged in a ring at 60° intervals at the top of the bridge plug; the lower probe includes four pressure contacts arranged in a ring at 90° intervals at the bottom of the bridge plug. Sand guards are provided around the pressure contacts. The pressure testing unit, including the upper probe at the top of the bridge plug and the lower probe at the bottom of the bridge plug, monitors pressure changes at the top and bottom of the bridge plug, respectively. This not only covers a wider pressure monitoring range but also improves data accuracy and reliability through multi-point sampling. Even if some probes are buried by sand, other contacts can continue to work, ensuring data continuity and integrity. Furthermore, a sand shield is installed on the outside of the pressure contact to protect it.

[0037] The signal transmission unit is connected to a ground signal receiving device 1 installed at the wellhead. The signal transmission unit transmits data to the ground signal receiving device 1 using pulse signals. The pulse signals are transmitted wirelessly, which is highly flexible and easy to install.

[0038] This invention discloses a digital bridge plug with a built-in pressure sensor that can acquire and transmit bottomhole pressure data in real time. This allows surface operators to monitor pressure changes during fracturing, enabling more precise fracturing control and adjustments. This helps improve the efficiency of fracturing operations and reduces potential problems caused by improper pressure control. Furthermore, the pressure sensor can be turned off before entering the well and activated just before entry, effectively avoiding unnecessary wear and tear and the risk of misoperation during transportation and installation, thus enhancing overall operational safety. Real-time monitoring of bottomhole pressure data allows for more accurate evaluation of fracturing effectiveness and timely adjustment of fracturing parameters, such as fracturing fluid injection rate and pressure, to achieve optimal fracturing results and improve oil and gas well production efficiency.

[0039] This invention also discloses an integrated method for inter-stage sealing and pressure measurement in hydraulic fracturing using the aforementioned digital bridge plug, characterized by comprising:

[0040] Step 1: After the hydraulic fracturing of the upper section of wellbore 2 is completed, turn on the power of pressure sensor 6 and use a cable pump to send the digital bridge plug to the designed position between the upper and lower sections of wellbore 2.

[0041] Step two: After the digital bridge plug is set, it expands to seal between sections, and then hydraulic fracturing continues in the next section. After the digital bridge plug enters the wellbore 2, the pressure sensor 6 measures the bottom hole pressure in real time and transmits it to the surface signal receiving device 1, completing the hydraulic fracturing section isolation and pressure measurement. This invention discloses an integrated method for hydraulic fracturing section isolation and pressure measurement. During the hydraulic fracturing process, a digital bridge plug is installed in the middle of each section of the wellbore. After the first section is fracturing is completed, the digital bridge plug is lowered into the middle position between the first and second sections using a cable pump. After the digital bridge plug is set, the sealing sleeve 5 of the digital bridge plug expands to seal between sections. Then, hydraulic fracturing is performed on the second section, and the steps are repeated until the entire well is hydraulically fracturing is completed. This achieves integrated inter-section isolation and real-time pressure measurement during the hydraulic fracturing process.

[0042] Step three: After receiving the signal, the ground signal receiving device 1 converts it into bottom hole pressure data for reading and storage. Based on the bottom hole pressure data, the net pressure during the hydraulic fracturing process is calculated, and a double logarithmic curve of net pressure versus time is plotted.

[0043] After receiving the signal, the ground signal receiving device converts it into bottom hole pressure data for reading and storage. Based on the bottom hole pressure data, the net pressure during the hydraulic fracturing process is calculated, and a double logarithmic curve of net pressure versus time is plotted. The double logarithmic curve can more intuitively show whether the fracture height is always under control during the artificial fracture propagation process and whether the fracture mainly extends within the reservoir. This allows for a more accurate assessment of the fracturing effect and timely adjustment of fracturing parameters, such as fracturing fluid injection rate and pressure, to achieve the best fracturing effect and improve the production efficiency and output of oil and gas wells.

[0044] The present invention will be further illustrated below through specific embodiments:

[0045] Example 1

[0046] Step 1: A horizontal well with a horizontal section length of 500 meters was drilled in a certain oil reservoir exploration block. In order to achieve full reservoir stimulation, the design adopted the bare casing segmented multi-cluster fracturing technology mode to fracture 4 stages, with 3 clusters in each stage. The fracturing injection flow rate was designed to be 12 cubic meters / minute, the injection volume of each stage was 800 cubic meters, and the sand addition volume was 120 cubic meters.

[0047] Step 2: To evaluate the fracturing effect, the bottom hole pressure needs to be recorded in real time during the fracturing process. Three sets of digital bridge plugs are designed as inter-section sealing tools, with one set of digital bridge plugs placed between every two sections.

[0048] Before the digital bridge plug is inserted into the well, the pressure sensor 6 is activated on the ground. Then, the digital bridge plug is lowered to the designed position between each two sections using a cable pump. After the digital bridge plug is set, the sealing rubber sleeve 5 in the middle expands to seal the section.

[0049] Step 3: The built-in pressure sensor 6 of the digital bridge plug starts working as soon as it enters the well. The pressure testing unit records the bottom hole pressure in real time, and the signal transmission unit transmits the bottom hole pressure to the surface in a pulse manner through the fluid in the wellbore and the casing in real time.

[0050] Step 4: The ground signal receiving device 1 connected to the wellhead receives the pressure signal transmitted from the bottom of the well to the ground in real time, and then converts the signal into digital data for reading and storage.

[0051] Step 5: Accurately calculate the net pressure during the fracturing process using the obtained bottom hole pressure data, plot the double logarithmic curve of net pressure versus time, and analyze that the fracture height is always under control during the artificial fracture propagation process, and the fracture mainly extends within the reservoir, achieving the designed stimulation purpose.

[0052] Example 2

[0053] Step 1: A shale oil block is planned to be developed using horizontal wells. During the fracturing process of the first well, it is necessary to accurately record the bottom hole pressure to conduct test fracturing analysis in order to evaluate key parameters such as fracturing fluid fracture creation efficiency, effective permeability, fracture extension pressure, and reservoir closure stress. The first horizontal well has a horizontal section length of 300 meters and is designed to use a bare casing segmented multi-cluster fracturing technology mode to fracture 5 stages, with 3 clusters in each stage. The designed fracturing injection rate is 15 cubic meters / minute. The fluid injection volume in each stage of the test fracturing phase is 150 cubic meters, and the fluid injection volume in the main fracturing phase is 800 cubic meters, with a sand addition of 100 cubic meters.

[0054] Step 2: The design uses 4 sets of digital bridge plugs as inter-section sealing tools. The first section uses tubing to transmit firepower perforation and smooth casing fracturing. After the first section is fracturing is completed, the digital bridge plug is lowered into the middle position between the first and second sections by cable pumping. Before the digital bridge plug is lowered into the well, the pressure sensor 6 is activated on the ground. After the digital bridge plug is set, the sealing rubber sleeve 5 in the middle expands to seal the inter-section.

[0055] Step 3: The built-in pressure sensor of the digital bridge plug starts working as soon as it enters the well. The pressure testing unit records the bottom hole pressure in real time, and the signal transmission unit transmits the bottom hole pressure to the surface in a pulse manner through the fluid in the wellbore and the casing.

[0056] Step 4: The ground signal receiving device 1 connected to the wellhead receives the pressure signal transmitted from the bottom of the well to the ground in real time, and then converts the signal into digital data for reading and storage.

[0057] Step 5: Repeat steps 2, 3, and 4 to fully fracturing the well. Each small-scale test fracturing stage requires 10 minutes of injection time, followed by a 2-hour shut-in period to allow fracture closure. After fracture closure, the main fracturing operation is initiated, lasting 58 minutes. Net pressure fitting analysis using the recorded bottomhole pressure yielded an average fracturing fluid fracturing efficiency of 67%, an effective permeability of 0.15 millidarcy, a fracture extension pressure of 34.7 MPa, and a reservoir closure stress of 31.2 MPa.

[0058] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A digitized bridge plug, characterized by, The bridge plug is provided with a pressure sensor (6) and a power supply for the pressure sensor (6); the pressure sensor (6) comprises a connected pressure testing unit and a signal transmission unit; the signal transmission unit is signal connected with a ground signal receiving device (1) arranged at a wellhead.

2. The digitized bridge plug of claim 1, wherein, The pressure testing unit comprises an upper probe arranged at the top of the bridge plug and a lower probe arranged at the bottom of the bridge plug.

3. The digitized bridge plug of claim 2, wherein, The upper probe comprises a plurality of pressure contacts arranged in a ring at the top of the bridge plug; the lower probe comprises a plurality of pressure contacts arranged in a ring at the bottom of the bridge plug.

4. The digitized bridge plug of claim 3, wherein, The upper probe comprises six pressure contacts arranged in a ring and spaced 60° at the top of the bridge plug; the lower probe comprises four pressure contacts arranged in a ring and spaced 90° at the bottom of the bridge plug.

5. The digitized bridge plug of claim 3, wherein, The pressure contacts are provided with a sand prevention cover.

6. The digitized bridge plug of claim 1, wherein, The signal transmission unit transmits data to the ground signal receiving device (1) by pulse signal.

7. A method of hydraulic fracturing interval isolation and pressure measurement using the digitized bridge plug of any one of claims 1-6, characterized in that, Comprise: Step one, after the upper section of the wellbore (2) is hydraulically fractured, the power supply of the pressure sensor (6) is turned on, and the digital bridge plug is pumped into the inter-section design position of the upper section and the next section of the wellbore (2) by cable; Step two, after the digital bridge plug is set, it is expanded for inter-section isolation, and then the next section is continuously hydraulically fractured; after the digital bridge plug enters the wellbore (2), the pressure sensor (6) measures the bottom hole pressure in real time and transmits it to the ground signal receiving device (1), completing the inter-section isolation and pressure measurement of hydraulic fracturing.

8. The method of claim 7, wherein, Also include: After the ground signal receiving device (1) receives the signal, it is converted into bottom hole pressure data for reading and saving.

9. The method of claim 8, wherein, Also include: Based on the bottom hole pressure data, the net pressure in the hydraulic fracturing process is calculated, and a double logarithmic curve of net pressure and time is drawn.

10. The method of claim 7, wherein, The inter-section design position is the intermediate position between the upper section and the next section of the wellbore (2) during hydraulic fracturing.

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