Research On Monitoring Method Of Gas Invasion While Drilling By Ultrasound

Safety ranks first,and well control has been paid much attention in the field of oil drilling engineering.Although killing methods are becoming more and more mature,the success of killing depends first on the discovery of gas invasion.If gas invasion is found late,with the evolution of gas invasion degree,the possibility of killing failure will be greatly increased.Ultrasound while drilling gas invasion monitoring method is a real-time gas invasion monitoring method in down hole with the drilling process using ultrasound as a means.This is an effective method to detect gas invasion earlier.Based on the thorough investigation of the current situation of ultrasonic application at home and abroad,a method of ultrasonic gas invasion monitoring while drilling based on Doppler effect is formed.The short section and experimental device of ultrasonic gas invasion monitoring while drilling are designed.The feasibility of ultrasonic gas bubble monitoring while drilling is verified by experiments.The signal detected by ultrasonic wave is analyzed and the gas invasion rate is quantified.Based on the experimental results,a set of implementable monitoring methods for gas invasion while drilling are developed.Main experimental results: In the clean water experiment,it is found that when the mainstream circulating flow rate remains unchanged all the time,the ultrasonic frequency shift signals detected in the gas-free state and the gas-invaded state differ more than 30%,and the ultrasonic frequency shift signals attenuate linearly with the increase of gas invasion.In mud experiments,it is found that when the mainstream flow rate is maintained relatively high(greater than 55 m3/h),the ultrasonic frequency shift signal decreases with the increase of the intake flow rate,and the ultrasonic frequency shift signal decreases more than 10% with the increase of the gas invasion fraction per 1%.The above experimental results show that the method of ultrasonic gas invasion monitoring while drilling can achieve earlier detection of gas invasion and help to judge the degree of gas invasion.