Research On The Ultrasonic Doppler Method Of Gas Cut Detection Along Riser

Deepwater well control are key points and difficulties in deepwater drilling,especially the kick caused by gas cut is more difficult to control,and the early detection of overflow is the key to the deepwater well control.Most traditional kick detection methods have a little limitation,Ultrasonic measurement has many characteristics,such as non-contact measurement,this paper mainly studies how to apply Ultrasonic measurement to detect overflow along riser,achieve the purpose of real-time gas cut detection.Applying ultrasonic measurement system based on time-difference method and Doppler method for water,water-based drilling fluid,oil-based drilling fluid gas cut detection were carried out,by changing the density of drilling fluid and gas void fraction,it was possible to analyze the changing characteristics of two kinds of measurement methods,evaluating the detection effect of the time-difference method and Doppler method on gas cut..This paper designs the deepwater drilling oil and gas flow detection device based on ultrasonic Doppler method,mainly including underwater monitoring module,the signal transmission system and signal analyze system,the device was tested in the south China sea no.2 platform,through the platform field experimentation,the sealing property of the underwater module and signal transmission system stability is verified fine.The results show that in the water as the continuous phase of gas cut experiment,gas void fraction from 0 to 15%,time-difference method and Doppler methods all can detect the gas void fraction of wellbore;In the gas cut experiments of water-based drilling fluid and oil-base drilling fluid,ultrasonic time-difference method measuring results are not has regularity,hence the time-difference method is not applicable to gas cut detection for drilling fluid;Ultrasonic Doppler method in water-base drilling fluid gas cut experimental measurement signal can obviously detect gas cut,when the void fraction was more than 1%,the gas cut of two different nature of the drilling fluid all can be detected by Doppler method,which can identify that the feasibility of Doppler method to detect the early kick is proved from this paper.