NEAR-BIT MULTI-PARAMETER DOWNHOLE MEASUREMENT AND CONTROL SYSTEM WHILE DRILLING

Abstract

A near-bit multi-parameter downhole measurement and control system while drilling, including a ground device and a downhole assembly. The downhole assembly includes a drill bit, a multi-parameter acquisition and signal transmission sub, a positive displacement motor or drilling tool, a receiving and transmitting module, a wireless communication sub, and a non-magnetic drill collar which are connected in sequence. The multi-parameter acquisition and signal transmission sub is provided with the near-bit measuring instrument. The receiving and transmitting module is configured to receive signals from the near-bit measuring instrument and transmit the signals to the wireless communication sub. The wireless communication sub is configured to transmit the received signals to the ground device through a mud pulse generator in a form of pulse signal, and the ground device decodes and analyzes downhole data. The system can monitor and adjust the real-time changes of downhole engineering parameters timely.

Description

TECHNICAL FIELD

The disclosure relates to the field of downhole data wireless measurement while drilling in drilling engineering, in particular to a near-bit multi-parameter downhole measurement and control system while drilling.

BACKGROUND

With the development of drilling technology, a near-bit measurement and control system while drilling has been developed in order to further improve the drilling efficiency and oil and gas recovery of deep wells, ultra-deep wells and horizontal wells with long displacement. Most of the existing measurement while drilling systems cannot solve simultaneously the measurement problems of a set of engineering parameters such as bottom hole temperature, internal and external annular pressure, triaxial vibrations, weight on bit, torque, rotation and bending moment, and the drilling efficiency is relatively slow.

SUMMARY

In order to solve the above technical problems, the disclosure provides a near-bit multi-parameter downhole measurement and control system while drilling, which can monitor the real-time changes of downhole engineering parameters in real-time, and adjust the drilling parameters such as weight on bit, rotation rate, torque, and drilling fluid performance during drilling process according to the changes of downhole parameters, As a result, the evaluation of drilling efficiency is not scientific and it is difficult to identify downhole complex situations in time.

A near-bit multi-parameter downhole measurement and control system while drilling, comprising a ground device and a downhole assembly.

The downhole assembly comprises a drill bit, a multi-parameter acquisition and signal transmission sub, a positive placement motor or a drill tool, a fishing joint, a receiving and transmitting module, a first connector, a wireless communication sub, a second connector and a non-magnetic drill collar which are connected in sequence.

The multi-parameter acquisition and signal transmission sub comprises a first drill collar, a power supply arranged on the first drill collar, a data processing circuit, a near-bit measuring instrument, a transmission antenna designed using vertical electric field method, an insulating ring and a data storage module; the near-bit measuring instrument is arranged on the first drill collar near the drill bit, and comprises a torque strain gauge, a weight on bit strain gauge, a pressure sensor, a temperature sensor, a triaxial accelerometer, and a circuit board; the near-bit measuring instrument is configured for data acquisition according to a preset time interval, and stores the acquisition data to the data storage module and transmits them to the data processing circuit; the data processing circuit is connected with the transmission antenna in communication connection; and the transmission antenna is configured to transmit signals to the receiving and transmitting module.

The receiving and transmitting module is configured to receive signals from the transmission antenna and transmit the signals to the wireless communication sub.

The wireless communication sub is configured to transmit the received signals to the ground device through a mud pulse generator in a form of pulse signals, and the ground device decodes and analyzes downhole data.

Further, a set of holes are provided on the first drill collar near a position of the drill bit, and the hole is configured for installing the near-bit measuring sensors.

Further, the measuring sensor like the torque strain gauge, the weight on bit strain gauge, the pressure sensor, the temperature sensor, the triaxial accelerometer, and the circuit board are arranged in the above holes respectively.

Further, an electromagnetic coupling transmission device is arranged inside the first connector and the second connector; the first connector is configured to achieve a transmission of electrical energy and data signals between the receiving and transmitting module and the wireless communication sub; and the second connector is configured to achieve a transmission of electrical energy and data signals between the wireless communication sub and the non-magnetic drill collar.

Further, a MWD measuring sub is provided inside the wireless communication sub, and data measured by the MWD measuring sub are collected and transmitted to the ground device by the wireless communication sub.

The advantageous effects: Compared with the prior art, the disclosure has the following technical effects:

The near-bit multi-parameter downhole measurement and control system while drilling can monitor the downhole engineering parameters in real-time such as torque, weight on bit, bending moment, temperature, pressure inside and outside drill string, rotation rate, and triaxial vibration. And the measurement position is closer to the drill bit, making the measurement data more realistic and accurate, such that it can monitor the real-time changes of downhole engineering parameters , and timely and accurately predict whether there are complicated downhole situations such as well kick, lost circulation, pipe sticking and drilling tools damage, which can greatly reduce the non-drilling time and improve the drilling efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 and FIG. 11 are schematic diagrams of the structure of a near-bit multi-parameter downhole measurement and control system while drilling;

FIG. 2 is a schematic diagram of the effect of the length of the multi-parameter acquisition and signal transmission sub on the wellpath deviation rate under certain operating conditions;

FIG. 3 is a schematic diagram of the effect of the length of the multi-parameter acquisition and signal transmission sub on the drill bit offset under certain operating conditions;

FIG. 4 is a schematic diagram of the multi-parameter acquisition and signal transmission sub;

FIG. 5 is a cross-sectional schematic diagram of the multi-parameter acquisition and signal transmission sub;

FIG. 6 is a cross-sectional view at A-A in FIG. 5;

FIG. 7 is a cross-sectional view at B-B in FIG. 5;

FIG. 8 is a cross-sectional schematic diagram of the wireless communication sub;

FIG. 9 is a cross-sectional schematic diagram of the first connector;

FIG. 10 is a cross-sectional schematic diagram of the second connector;

FIG. 12 is a physical diagram of an electromagnetic coupling transmission device.

Number references in the drawings: 1—drill bit; 2—multi-parameter acquisition and signal transmission sub; 21—hole; 3—screw power drill tool; 4—fishing joint; 5—receiving and transmitting module; 6—first connector; 7—wireless communication sub; 8—second connector; 9—non-magnetic drill collar; 10—ground device; 20—downhole assembly; 201—first drill collar; 22—power supply; 23—data processing circuit; 24—near-bit measuring instrument; 25—transmission antenna; 26—insulation ring; 27—data storage module; 241—torque strain gauge; 242—WOB (Weight On Bit) strain gauge; 243—pressure sensor; 244—temperature sensor; 245—triaxial accelerometer; 246—circuit board; 61—electromagnetic coupling transmission device; 71—mud pulse generator; 72—MWD measuring sub.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown in FIGS. 1, 4-7, and 10, a near-bit multi-parameter downhole measurement and control system while drilling is provided, which includes a ground device 10 and a downhole assembly 20.

Specifically, the ground device 10 includes a pressure sensor, a wireless transceiver host, a wireless sensor host, a driller display, and a data processing instrument.

As shown in FIGS. 1-10, the downhole assembly 20 includes a drill bit 1, a multi-parameter acquisition and signal transmission sub 2, a screw power drill tool 3, a fishing joint 4, a receiving and transmitting module 5, a first connector 6, a wireless communication sub 7, a second connector 8 and a non-magnetic drill collar 9 which are connected in sequence.

Wherein, the multi-parameter acquisition and signal transmission sub 2 includes a first drill collar 201, a power supply 22 arranged on the first drill collar 201, a data processing circuit 23, a near-bit measuring instrument 24, a transmission antenna 25 designed using vertical electric field method, an insulating ring 26 and a data storage module 27.

More specifically, the near-bit measuring instrument 24 is arranged on the first drill collar 201 near the drill bit 1, which includes a torque strain gauge 241, a weight on bit strain gauge 242, a pressure sensor 243, a temperature sensor 244, a triaxial accelerometer 245, and a circuit board 246. The near-bit measuring instrument 24 is configured to collect data according to a preset time interval, and stores the collected data to the data storage module 27 and transmits the collected data to the data processing circuit 23. The data processing circuit 23 is connected with the transmission antenna 25 in communication connection, and the transmission antenna 25 is configured to transmit signals to the receiving and transmitting module 5. The receiving and transmitting module 5 is configured to receive signals from the transmission antenna 25 and transmit the signals to the wireless communication sub 7. The wireless communication sub 7 is configured to transmit the received signals to the ground device 10 through a mud pulse generator 71 in a form of pulse signal, and the ground device 10 decodes and analyzes downhole data.

First of all, the near-bit measuring instrument 24 includes the torque strain gauge 241, the weight on bit strain gauge 242, the pressure sensor 243, the temperature sensor 244, the triaxial accelerometer 245, and the circuit board 246 which is connected with the above instruments through electrical signals. In this way, it can measure parameters such as weight on bit, bending moment, temperature, inner and outer ring pressure, triaxial vibration, etc. during drilling. The measured parameters are more abundant, which can greatly improve the drilling efficiency.

Secondly, by setting the near-bit measuring instrument 24 set at the multi-parameter acquisition and signal transmission sub 2 and located near the drill bit 1, it has at least two advantages:

On the one hand, due to the parameter measurement position close to the drill bit 1, its measurement data is closer to the drilling operation position and more accurate.

On the other hand, the aforementioned measuring instruments set on the multi-parameter acquisition and signal transmission sub 2 can control the length of the multi-parameter acquisition and signal transmission sub 2 within 1.2 m, effectively ensuring the deflection rate near the drill bit 1 and reducing the impact of the multi-parameter acquisition and signal transmission sub 2 on the offset of the drill bit 1 during drilling. The details are as follows:

Due to the significant impact of the position of the multi-parameter acquisition and signal transmission sub 2 on the deflection rate of the single bend screw drill tool, the deflection rate will decrease due to the length distance between the position of the multi-parameter acquisition and signal transmission sub 2 and the drill bit 1, and may even lose the deflecting capacity at a long distance.

As shown in FIGS. 2-3, FIG. 2 shows the relationship between the length of the multi-parameter acquisition and signal transmission sub 2 and the wellpath deviation rate under certain operating conditions; FIG. 3 shows the relationship between the length of the multi-parameter acquisition and signal transmission sub 2 and the offset distance of the drill bit 1 under certain operating conditions.

Wherein, the certain operating conditions refer to:

1. Bottom hole assembly (BHA): the drill bit 1 has a diameter of 215.9 mm and a length of 0.25 m, the positive displacement motor 3 has a diameter of 172 mm and a total length of 7.95 m, with bending angles of 1.0° and −1.5°. The bending angles are 1.4 m away from the end face of drill bit 1, and the center position of the multi-parameter acquisition and signal transmission sub 2 is 0.6 m away from the end face of the drill bit 1.

2. Drilling parameters and wellbore conditions: drilling pressure is 60 kN, wellbore inclination angle is 45°, anisotropy index of the drill bit 1 is 0.05, specific gravity of drilling fluid is 1.25, formation inclination angle is 5°, and formation anisotropy index is 0.99.

From FIG. 1 and FIG. 2, it can be clearly seen that the position and length of the multi-parameter acquisition and signal transmission sub 2 have a significant impact on the deflection rate of the single bend screw drill tool. The deflection rate will rapidly decrease as the position of the multi-parameter acquisition and signal transmission sub 2 becomes farther away, and even lose its deviation build-up capacity. Moreover, when the length of the multi-parameter acquisition and signal transmission sub 2 is 1.2 m or less, the effect of the multi-parameter acquisition and signal transmission sub 2 on the increment of deviation build-up rate is better.

Furthermore, referring to FIG. 4 to FIG. 7, in some embodiments, a hole 21 is provided on the first drill collar 201 near the position of the drill bit 1, and the hole 21 is configured for setting the near-bit measuring instrument 24. By setting the near-bit measuring instrument 24 in the hole 21 of the first drill collar 201, the near-bit measuring instrument 24 can be hidden in the side wall of the first drill collar 201. During the drilling operation of the drill bit 1, there is little friction between the near-bit measuring sut 24 and the wellbore wall, thereby improving the detection accuracy of various downhole measurement data.

Further, as shown in FIG. 4 to FIG. 6, in some embodiments, a number of the holes 21 are provided, and the torque strain gauge 241, the weight on bit strain gauge 242, the pressure sensor 243, the temperature sensor 244, the triaxial accelerometer 245, and the circuit board 246 are arranged in each hole 21 respectively. In this way, the assembly of each measuring instrument is convenient.

Referring to FIG. 9, FIG. 10 and FIG. 12, in some embodiments, both the first connector 6 and the second connector 8 are internally equipped with an electromagnetic coupling transmission device 61. The electromagnetic coupling transmission device 61 includes a outer ring of copper ring and an electromagnetic coil arranged inside the outer ring of copper ring. The first connector 6 is used to achieve the transmission of electrical energy and data signals between the receiving and transmitting module 5 and the wireless communication sub 7. The second connector 8 is used to achieve the transmission of electrical energy and data signals between the wireless communication sub 7 and the non-magnetic drill collar 9.

By setting the electromagnetic coupling transmission device 61 in the first connector 6 and the second connector 8, it can achieve synchronous transmission of electrical energy and data signals through the wireless transmission technology of magnetic coupling resonance while connecting the receiving and transmitting module 5 to the wireless communication sub 7, as well as the wireless communication sub 7 to the non-magnetic drill collar 9.

Referring to FIG. 8, in some embodiments, a MWD (measurement-while-drilling) measuring sub 72 is provided inside the wireless communication sub 7, the wireless communication sub 7 collects data measured by the MWD measuring sub 72 and transmits it to the ground device 10 in the form of a pulse signal through the mud pulse generator 71.

In addition to the MWD measuring sub 72, the wireless communication sub 7 is also equipped with a signal receiving device, a main control circuit, a signal encoding circuit, and the mud pulse generator 71. After receiving data, the main control circuit is used to store the data.

Specifically, a signal processing circuit and a signal transmission device for the drill bit 1 system are installed in the wireless communication sub 7, which is used to transmit the preprocessed signal through the second connector 8 to the non-magnetic drill collar 9 through electromagnetic wave wireless short transmission. The data is stored by the main control circuit in the non-magnetic drill collar 9, and then controlled by the mud pulse driving circuit to transmit the pulse signal to the ground device 10 through the mud pulse generator 71.

Due to the traditional wireless short transmission technology with a transmission rate of 50 bit/s, the transmission speed from MWD mud pulse generator 71 to the ground device 10 is 1 bit/s. There is a significant difference in the transmission rate between the two, and the transmission bandwidth of MWD mud pulse generator is small, resulting in the inability of the multi-parameter acquisition and signal transmission sub 2 to directly transmit signals to the main control system of MWD through wireless short transmission technology. Therefore, it is necessary to transform the data into a data transmission sequence that adapts to the mud pulse transmission speed. For this purpose, the signal of the multi-parameter acquisition and signal transmission sub 2 is pre-stored through the wireless communication sub 7. At the same time, the wireless communication sub 7 compresses the signal quantity, processes the detected parameter signal according to the instructions of the ground device 10, and transmits it to the signal encoding circuit. Finally, the mud pulse driving circuit controls the mud pulse generator 71 to transmit the pulse signal to the ground device 10, and then the ground device 10 receives and decodes downhole data to achieve real-time transmission of downhole data to the ground.

Claims

1. A near-bit multi-parameter downhole measurement and control system while drilling, comprising a ground device and a downhole assembly, wherein the downhole assembly comprises a drill bit, a multi-parameter acquisition and signal transmission sub, a screw power drill tool, a fishing joint, a receiving and transmitting module, a first connector, a wireless communication sub, a second connector and a non-magnetic drill collar which are connected in sequence;the multi-parameter acquisition and signal transmission sub comprises a first drill collar, a power supply arranged on the first drill collar, a data processing circuit, a near-bit measuring instrument, a transmission antenna designed using vertical electric field method, an insulating ring and a data storage module; the near-bit measuring instrument is arranged on the first drill collar near the drill bit, and comprises a torque strain gauge, a weight on bit strain gauge, a pressure sensor, a temperature sensor, a triaxial accelerometer, and a circuit board; the near-bit measuring instrument is configured for data acquisition according to a preset time interval, and stores the collected data to the data storage module and transmits them to the data processing circuit; the data processing circuit is connected with the transmission antenna in communication connection; and the transmission antenna is configured to transmit signals to the receiving and transmitting module;the receiving and transmitting module is configured to receive signals from the transmission antenna and transmit the signals to the wireless communication sub; andthe wireless communication sub is configured to transmit the received signals to the ground device through a mud pulse generator in a form of pulse signal, and the ground device decodes and analyzes downhole data.

2. The near-bit multi-parameter downhole measurement and control system while drilling according to claim 1, wherein a number of holes are provided on the first drill collar near a position of the drill bit, and the hole are configured for setting the near-bit measuring instruments.

3. The near-bit multi-parameter downhole measurement and control system while drilling according to claim 2, wherein the hole are provided for installing sensors such as torque strain gauge, the weight on bit strain gauge, the pressure sensor, the temperature sensor, the triaxial accelerometer, and the circuit board correspondingly

4. The near-bit multi-parameter downhole measurement and control system while drilling according to claim 1, wherein an electromagnetic coupling transmission device is arranged inside the first connector and the second connector; the first connector is configured to achieve a transmission of electrical energy and data signals between the receiving and transmitting module and the wireless communication sub; and the second connector is configured to achieve a transmission of electrical energy and data signals between the wireless communication sub and the non-magnetic drill collar.

5. The near-bit multi-parameter downhole measurement and control system while drilling according to claim 1, wherein a MWD measuring sub is provided inside the wireless communication sub, and data measured by the MWD measuring sub are collected and transmitted to the ground device by the wireless communication sub.