Nested leather cup sealing intelligent monitoring composite rubber plug

Abstract

The invention relates to the technical field of petroleum well cementation, in particular to a nested leather cup sealing intelligent monitoring composite rubber plug which comprises a guide head, a leather cup unit and a pressure monitoring device. The device is characterized in that the leather cup units are connected in series at the rear end of the guide head through threads, and the pressure monitoring devices are mounted between the adjacent leather cup units through threads; the leather cup unit comprises a core rod and a nested rubber cup; the pressure monitoring device comprises a dowel bar, a device shell, a pressure sensitive element, a signal processing and sending module and a sealing ring; the signal processing and transmitting module comprises a signal converter, a signal modulator, a signal transmitter and a matched ground receiver. Through the design of the nested leather cup, the problem of sealing failure caused by abrasion of a traditional single leather cup can be solved; meanwhile, the pressure monitoring device can feed back pressure data in the descending process of the rubber plug in real time, the problem that the underground sealing state of the rubber plug in well cementation operation cannot be monitored is solved, the operation efficiency is improved, and the well cementation quality is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil well cementing, and particularly relates to a nested cup seal intelligent monitoring composite plug. Background Art

[0002] In cementing operations, plugs are mainly used to isolate different fluids, clean the pipe wall, and achieve efficient displacement of cement slurry.

[0003] The sealing performance of the plug in the wellbore is crucial. Once the seal fails, it may pose a threat to the integrity of the wellbore. In actual operations, traditional single cup plugs have problems such as damage and shedding of the rubber cups due to long-term wear, resulting in cross-flow between the cement slurry and the drilling fluid, leading to large-area pollution and affecting the cementing quality. Wear will cause defects such as pits and scratches on the surface of the plug, reducing the contact area between the plug and the pipe wall, forming a fluid bypass channel, and causing a large amount of cementing fluid to remain in the pipe without being effectively displaced, affecting the displacement efficiency.

[0004] Traditional plugs rely on the interference fit between the cup and the pipe wall to achieve physical sealing. However, due to the lack of built-in monitoring elements, they cannot obtain the pressure data of the plug in the wellbore in real time, resulting in the sealing effect relying on the readings of the surface pressure gauge for a long time. And this method has obvious hysteresis: when an abnormality is found through the surface pressure signal, large-scale fluid cross-mixing has often occurred, leading to serious accidents such as drilling fluid leakage and cement slurry pollution.

[0005] Therefore, there is an urgent need to develop a plug with stable sealing and scraping ability, which can also monitor the sealing state of the plug in real time, to meet the urgent needs of deep well and ultra-deep well cementing operations. Summary of the Invention

[0006] In view of the phenomenon that the traditional cup of the plug tears and slips during the downward movement due to friction, resulting in seal failure, and the problem that the sealing state of the plug cannot be monitored in real time during downhole operations, a nested cup seal intelligent monitoring composite plug is designed.

[0007] To achieve the above object, the present invention is implemented by the following technical solutions: A nested cup seal intelligent monitoring composite plug, comprising a guide head, a cup unit, and a pressure monitoring device, characterized in that: The front end of the guide head is conical, the rear end is cylindrical, and the cone top is hemispherical.

[0008] The cup unit includes nested cups and a core rod. Four cup units are connected in series through threaded holes and studs provided on the core rod and then connected to the rear end of the guide head.

[0009] The pressure monitoring device includes a force transfer rod, a pressure-sensitive element, a signal processing and transmitting module, a sealing ring, and a device housing, and is connected between adjacent cup units through threaded holes and studs provided on the force transfer rod and the device housing.

[0010] Further, a groove is provided in the middle of the cylindrical part of the guiding head, and a connecting hole is provided at the rear end, and a thread is provided in the hole.

[0011] Further, the nested rubber cup is composed of a plurality of rubber cups, including two scraping wings with the same diameter and different tapers. The diameter of the rubber cup is determined according to the size of the drilling tool. The diameter of the rubber cup should be larger than the inner diameter of the drilling tool in the natural state, so that the rubber cup can fit with the inner wall after entering the drilling tool to form a sealing and scraping effect. The nested rubber cup is attached to the core rod by a high-temperature vulcanization process using a super-elastic material with high strength, high toughness, and high wear resistance.

[0012] Further, the core rod is a stepped shaft in terms of its structural characteristics. A threaded connecting hole is provided at the end face of the shaft section with a larger diameter, and a threaded connecting post is provided at the end face of the shaft section with a smaller diameter.

[0013] Further, the force transfer rod is cylindrical, and a threaded connecting hole is provided at one end.

[0014] Further, the device housing is a cylinder with a cavity inside. There is a round hole at one end that penetrates through to the internal cavity, and the diameter of the round hole is smaller than the diameter of the internal cavity; it is equal to the diameter of the force transfer rod. A threaded connecting post is provided at the other end.

[0015] Further, the force transfer rod is matched with the round hole at the end face of the device housing, and the gap seal between the two is realized by the sealing ring provided on the inner wall of the round hole.

[0016] Further, the cavity between the force transfer rod and the device housing is used to accommodate the signal processing and transmitting module and the pressure-sensitive element, and the pressure-sensitive element is arranged directly below the force transfer rod.

[0017] Further, the pressure-sensitive element is a pressure sensor.

[0018] Further, the signal processing and transmitting module includes a signal converter, a signal modulator, a signal transmitter, and a supporting surface receiver.

[0019] Further, the signal converter is a charge amplifier or a voltage follower, which converts the charge signal or high-impedance signal output by the pressure sensor into a standard voltage signal to adapt to the subsequent circuit.

[0020] Further, the signal modulator is an instrumentation amplifier and a filter, which uses the amplifier to amplify the standard voltage signal and eliminates downhole electromagnetic interference and high-frequency noise through the filter.

[0021] Furthermore, the signal transmitter is wirelessly transmitted, adopts electromagnetic wave transmission technology, encodes electrical signals into electromagnetic waves of specific frequencies, and uses formation media or mud as a transmission carrier to achieve signal transmission.

[0022] Furthermore, the ground receiver is a receiving device matched with the signal transmitter.

[0023] During cementing operations, the rubber plug moves downward under the push of the fluid pressure difference at the front and rear ends. The nested leather cup design ensures that at least one leather cup is in contact with the pipe string, avoiding the sealing failure caused by tearing or slipping of the traditional single leather cup. At the same time, the nested leather cup design can avoid the weakening of the scraping ability of a single leather cup due to wear.

[0024] The fluid pressure difference to which the rubber plug is subjected during its descent is transmitted to the force transmission rod of the pressure monitoring device through the leather cup and the core rod, and acts on the pressure sensor through the force transmission rod. The signal converter converts the charge signal or high impedance signal output by the pressure sensor into a standard voltage signal to adapt to the subsequent circuit; the signal modulator amplifies and filters the converted standard voltage signal; the signal transmitter encodes the modulated electrical signal into an electromagnetic wave of a specific frequency, and uses the formation medium or mud as a transmission carrier to send it back to the ground; the ground receiver separates the target signal through a matching filter, and the digital-to-analog converter converts the analog signal into a digital signal, and performs data analysis and visualization through an industrial computer. In this way, ground operators can monitor the pressure data of the rubber plug in the well in real time. Beneficial Effects

[0025] The nested leather cup seal intelligent monitoring composite rubber plug of the present invention has the characteristics of strong scraping ability, good sealing, and no hysteresis in pressure detection. It solves the problems of weakened scraping ability, sealing failure, and inability to monitor pressure in real time due to leather cup wear in traditional single leather cup rubber plugs underground, thereby improving cementing efficiency.

[0026] The nested leather cup design can enhance the scraping ability of the rubber plug, more thoroughly remove impurities on the inner wall of the pipe, and improve the cleanliness of the pipe. At the same time, when some leather cups are damaged, it can still ensure that at least one leather cup is in contact with the pipe to maintain the sealing performance, effectively avoiding the mixing of cementing fluid and drilling fluid caused by the failure of a single leather cup, and ensuring the safety of cementing operations.

[0027] The pressure monitoring device can obtain the fluid pressure difference data of the front and rear ends of the rubber cup in real time during the rubber plug's descent, providing accurate and immediate information on the pressure of the rubber plug to the ground operators. The ground operators can monitor the sealing anomalies of the rubber plug in the well through real-time pressure data, and take corresponding measures in time to avoid accidents such as "stuffing sausages" in the tail pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] To better illustrate the structure of a nested leather cup pressure monitoring intelligent rubber plug, it is described in conjunction with the accompanying drawings.

[0029] Figure 1 Schematic diagram of the structure of a nested leather cup sealing intelligent monitoring composite rubber plug according to the present invention; Figure 2 For Figure 1 Schematic diagram of the rubber plug leather cup structure taking the first leather cup unit 10 as an example in Figure 3 For Figure 1 Schematic diagram of the structure of the pressure monitoring device 70 in Figure 4 For Figure 1 Working principle and signal processing flowchart of the pressure monitoring device 70 in

[0030] In the figure: 10 - first leather cup unit, 20 - second leather cup unit, 30 - third leather cup unit, 40 - fourth leather cup unit, 50 - guiding head, 60 - casing, 70 - pressure monitoring device, 101 - core rod, 102 - nested rubber cup, 103 - first scraping wing, 104 - second scraping wing, - first scraping angle, - second scraping angle, 701 - force transmission rod, 702 - device housing, 703 - sealing ring, 704 - signal processing and sending module, 705 - pressure sensitive element. Specific implementation method

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are some but not all of the embodiments of the present invention. Generally, the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0033] The present invention will be further described below in conjunction with the accompanying drawings: Figure 1Shows a structural diagram of a nested cup seal intelligent monitoring composite rubber plug of the present invention, including a guiding head 50, a first cup unit 10, a pressure monitoring device 70, a second cup unit 20, a third cup unit 30, and a fourth cup unit 40. Each cup unit is arranged in ascending order of diameter size and is installed at the rear end of the guiding head 50 through threaded connection. Cup units of different sizes are adapted to drill pipes with different inner diameter sizes. The pressure monitoring device 70 is arranged between adjacent cup units to achieve the sealing monitoring function of each cup.

[0034] Figure 2 Shows Figure 1 A structural diagram of the rubber plug cup with the first cup unit 10 as an example, including a core rod 101 and a nested rubber cup 102. The nested rubber cup includes a first scraping wing 103 and a second scraping wing 104, and the first scraping angle is smaller than the second scraping angle . The nested rubber cup is attached to the core rod after being vulcanized at high temperature with a super-elastic material, making the cup have characteristics such as high tear resistance and high wear resistance. The diameter of the rubber cup is determined according to different drill pipe sizes. In the natural state, its diameter should be slightly larger than the inner diameter of the drill pipe, so that when the rubber plug is inserted into the drill pipe, the rubber cup generates an initial contact force through the interference fit with the inner diameter of the drill pipe. Under the action of the fluid pressure at the rear end, the rubber plug cup fully contacts the pipe wall to form an effective seal.

[0035] Figure 3 Shows Figure 1 A schematic structural diagram of the pressure monitoring device 70. The pressure monitoring device is composed of a force transmission rod 701, a device housing 702, a sealing ring 703, a signal processing and sending module 704, and a pressure sensitive element 705. The force transmission rod 701 is a cylindrical structure with a threaded connection hole at one end; one end of the device housing 303 is provided with a threaded connection post, and the other end face is provided with a blind hole. The force transmission rod 701 is installed in the blind hole. The cavity formed between the force transmission rod 701 and the device housing is used to accommodate the signal processing and sending module 704, and a pressure sensitive element 705 is arranged directly below the force transmission rod 701. The gap between the force transmission rod 701 and the device housing is sealed with a sealing ring 703.

[0036] Figure 4 Shows Figure 1 The working principle diagram and signal processing flow chart of the pressure monitoring device 70. After a nested cup seal intelligent monitoring composite rubber plug of the present invention is inserted into the drill pipe, it slides forward deep into the formation under the action of the fluid pressure difference between the front and rear. When the rubber plug operates underground, the fluid driving force received by the cup is transmitted to the force transmission rod 701 through the nested rubber cup 102 and the core rod 101, thereby realizing the conversion of fluid pressure and mechanical pressure.

[0037] The operation process of the pressure monitoring device is as follows: 1. Information acquisition: A piezoresistive or strain - type pressure sensor is used to convert mechanical pressure into a weak voltage signal by sensing the pressure change of the force - transmitting rod. This signal has characteristics such as non - linearity and susceptibility to interference and needs to be pre - processed.

[0038] 2. Signal conversion: A charge amplifier or a voltage follower is used to convert the charge signal or high - impedance signal output by the sensor into a standard voltage signal to adapt to the subsequent circuit.

[0039] 3. Signal modulation: An instrumentation amplifier is used to amplify the signal, and a band - pass filter is used to eliminate underground electromagnetic interference and high - frequency noise.

[0040] 4. Signal transmission: Downhole acoustic or electromagnetic wave technology is used to encode the electrical signal into an acoustic wave or electromagnetic wave of a specific frequency, and the formation or mud is used as the transmission medium to transmit the signal to the ground.

[0041] 5. Ground reception: The ground receiving device separates the target signal through a matched filter, converts the analog signal into a digital signal through analog - to - digital conversion, and finally performs data analysis and visualization display on an industrial computer.

[0042] Regarding the limitations of the embodiments, the above - described embodiments and the description in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, any modifications and changes made by those skilled in the art that do not depart from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A nested leather cup seal intelligent monitoring composite rubber stopper, comprising a guide head 50, four leather cup units (10 - 40) and three pressure monitoring devices 70, characterized in that: The front end of the guide head 50 is conical, and the rear end is cylindrical; a connection hole is provided on the cylindrical end face, and a thread is provided in the hole. After four leather cup units are connected in series, they are installed at the rear end of the guide head 50 through this connection hole. The leather cup unit includes a core rod 101 and a nested rubber cup 102. It is characterized in that: the core rod 101 is a stepped shaft. A connection hole with a thread is provided on the end face of the large-diameter shaft section, and a connection column with a thread is provided on the end face of the small-diameter shaft section. Each leather cup unit is connected in series in this way; the nested rubber cup 102 is attached to the core rod 101 after being vulcanized at high temperature by a rubber material, and mainly includes two scraping wings with different scraping angles, namely a first scraping wing 103 and a second scraping wing 104. The pressure monitoring device is arranged between adjacent leather cup units and mainly includes a force transmission rod 701, a device housing 702, a sealing ring 703, a signal processing and sending module 704, and a pressure sensitive element 705. It is characterized in that: a connection hole with a thread is provided at one end of the force transmission rod 701, and a connection column with a thread is provided at one end of the device housing 702; relying on the threads of the force transmission rod 701 and the device housing 702 to be connected with the threaded hole and the threaded column of the core rod 101. The device housing 702 is a cylinder, and there is a cavity inside; a round hole is provided at one end and is in communication with the cavity. The diameter of the internal cavity is larger than the diameter of the round hole on this end face. A connection column with a thread is provided at the other end face; the diameter of the force transmission rod 701 is the same as the diameter of the round hole on the end face of the device housing 702, and a connection column with a thread is provided at one end face thereof; the force transmission rod 701 is matched with the round hole on the end face of the device housing 702, and the gap seal between the two is realized by the sealing ring 703 provided on the inner wall of the round hole on the end face of the device housing 702. The cavity between the force transmission rod 701 and the device housing 702 is used to accommodate the pressure sensitive element 705 and the signal processing and sending module 704, and the pressure sensitive element 705 is arranged directly below the force transmission rod 701 in the cavity.

2. The nested leather cup seal intelligent monitoring composite rubber stopper according to claim 1, characterized in that The pressure sensitive element is a piezoresistive or strain type pressure sensor.

3. The nested leather cup seal intelligent monitoring composite rubber stopper according to claim 1, characterized in that The signal processing and sending module 704 includes: a signal converter, a signal modulator, a signal transmitter and a supporting ground receiver. The signal converter is a charge amplifier or a voltage follower, which converts the charge signal or high-impedance signal output by the pressure sensor into a standard voltage signal to adapt to the subsequent circuit. The signal modulator includes an instrumentation amplifier and a filter, which amplifies the standard voltage signal by using the amplifier and eliminates downhole electromagnetic interference and high-frequency noise through the filter. The signal transmitter is a wireless transmission module, which uses electromagnetic wave transmission technology to encode the electrical signal into electromagnetic waves of a specific frequency and uses the formation medium or mud as the transmission carrier to realize signal transmission in deep wells and ultra-deep wells. The ground receiver separates the target signal through a matching filter, converts the analog signal into a digital signal through analog-to-digital conversion, and performs data analysis and visualization display through an industrial computer.

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