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.

What is claimed is: 
     
         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; and   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.   
     
     
         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.