Research On Communication Of Downhole Single-core Cable And Remote Monitoring Technology

With puting forward the fine measuring and regulating ways of separate layer water injection and separate layer gas injection and so on in China's major oil fields,the wellhead or remote monitoring center needs to measure and regulate the downhole measurement and control equipment in real time through the transmission system.Aiming at the problems such as high cost,poor reliability and poor adaptability of current downhole communication system,this topic has designed a set of downhole single-core cable communication and remote monitoring system,which realized the downhole?wellhead and remote monitoring room three-level transmission system.The main work of the paper and research results are as follows:For external conditional restrictions such as high temperature,multi-interference and small size installation in the downhole,Combined with the status of the downhole communication systems and process requirements,the single-core cable has the advantages of small volume and convenient installation in the downhole,which determined that the single-core armored cable is used as the communication carrier of the wellhead ground controller and the downhole monitoring and control equipment.The effective communication frequency range,communication distance and DC voltage range of single-core cable are determined by simulation analysis of amplitude-frequency characteristic and phase-frequency characteristic of single-core cable.Completed the hardware and software design of the downhole communication short section and the ground controller,achieved a ground controller and a number of the downhole monitoring and control equipment,two-way communication,DC power supply through a single-core cable with the bus-type DC carrier communication technology.Power module to achieve from the single-core cable to obtain direct current,and converted into the corresponding voltage for the underground control circuit and motor power supply;the coding and decoding module implements the bidirectional transmission of the signal on the single-core cable.The single-core cable communication protocol is designed,and the Manchester code is adopted at the physical layer.The protocol layer adopts the standard Modbus protocol to reduce the bit error rate and realize the low data frame length Transparent two-way communication in 256 bytes;the programmable controller of the ground controller and the programmable amplifier of the downhole measurement and control device are designed to realize the communication technology of the adaptive cable length,which meets the requirements of different depth power supply and communication in the underground measurement and control device.Completed the software design of remote monitoring system,the remote monitoring center and a number of the ground controller(wellhead)signal bidirectional transparent transmission is realized by the GPRS wireless communication,the remote monitoring center and the downhole measurement and control equipment signal bidirectional transparent transmission is realized.The remote monitoring center published monitoring interface through the form of web,the user or technicians with authority can momentarily accessible web pages via mobile phone and the remote computer.The single-core cable communication and remote monitoring system for experimental testing through the simulation of the well in the laboratory.The experimental results show that under the conditions of single-core cable length of 1-5km,the downhole control and control equipment is normal,underground,wellhead,remote monitoring room three normal communication,to meet the requirements of low-speed communication technology.