Research And Design Of A Gas Drilling Downhole Measurement System

Gas drilling is a way of underbalanced drilling,which developed rapidly in recent years it due to the advantage of improving the mechanical drilling speed and the protection of oil and gas production. In order to ensure the security of gas drilling, the parameters of all kinds of drilling engineering should be monitored in real time.However, mud pulse MWD need to be powered by drilling fluid, which is not suitable for gas drilling. Electromagnetic wave MWD is greatly influenced by stratum medium with a limited measuring depth, which is subjected strictly blockaded by foreign companies with an expensive service charges, Therefore, it is necessary to develop a suitable MWD system for gas drilling.Based on the current parameters measurement such as the deviation angle, azimuth and temperature of the well, this paper study the measurement method of WOB and torque measurement and increase the measurement, and according to the existing gas drilling technology, the wireless MWD technology of microwave signal relay in drill string was studied. The research on the principle and method of angle method to measure torque was carried out, which provides a new method for measuring the torque of the near-bit, the principle of strain method to measure WOB and torque is studied to design the arranging bridging of strain gauge, and the analysis of output was completed, and this paper analyzed the circuit how to eliminate the coupled effects in all parameters; The hardware design of WOB and torque measuring subs was complete, the signal conditioning circuit and other related circuit were designed, and the software design of WOB and torque measuring was completed, this paper established the simulation model of measuring subs to obtain the simulation calculation of stress which based on the ANSYS workbench 14.5, the result of simulation verify the rationality of the structure design and provide theoretical basis for WOB and torque measurement; In order to provide theoretical basis for improving the signal transmission distance, the microwave transmission characteristics of drill string were studied, and the test experiment is carried out, the scheme design of microwave data relay transmission in the drill string was completed, and ZigBee single chain network was realized, the scheme design of microwave signal receiving was completed; The real time monitoring system software were designed and developed; The test results of laboratory and field verify the correctness of theoretical research and the practicability and feasibility of data relay transmission scheme, which provides a theoretical basis for the optimization and upgrading of the system.Field test shows that the design of the gas drilling MWD system can achieve a real-time monitoring of downhole parameters. It can effectively avoid the safety risk in the process of drilling and provides the key technical support for the safe and efficient construction of gas drilling.