Deepwater drilling well gas cut monitoring method based on marine riser gas-liquid two-phase flow identification

Abstract

The invention belongs to the deepwater oil gas drilling well field, and specifically relates to a deepwater drilling well gas cut monitoring method based on marine riser gas-liquid two-phase flow identification; the method comprises the following steps: arranging ultrasonic transducers in contrapositions on bottom of the marine riser so as to monitor gas cut signals; according to a set quantification corresponding relation between sound wave signal attenuation and cross section gas contain rate, combining a deepwater drilling well shaft gas liquid two-phase flow model and a credibility containing stratum pressure prediction method so as to set up a shaft gas cut level inverse computation method based on marine riser gas cut monitoring data, thus spotting gas cut in advance, realizing real time quantification description of the shaft gas cut condition, and forming the deepwater drilling well gas cut monitoring method based on marine riser gas-liquid two-phase flow identification. The method can measure more real data, can fully reflect the cross section gas containing rate, and can correct bottom hole prediction originality pressure according to marine riser sound wave monitoring data, so the shaft gas cut level inverse computation result can be more closer to real conditions, and reasonable measurement can be taken to control gas cut.

Description

technical field [0001] The invention belongs to the field of deep-water oil and gas drilling, and in particular relates to a method for monitoring gas intrusion in deep-water drilling based on the identification of gas-liquid two-phase flow in risers. Background technique [0002] During the drilling process, if a high-pressure gas layer is drilled, gas kick will occur. It is difficult to detect the gas kick in the initial stage by means of mud pool liquid level detection, flow difference overflow detection and other methods or equipment. With the increase of well depth, it can be detected early The difficulty of gas invasion increases, and the reaction time left for well control is significantly reduced, making the early detection of gas invasion an important and difficult point in well control of deep wells. For deepwater drilling, firstly, gas kick is more likely to occur as the kick allowance decreases with the increase of water depth; secondly, in the deepwater high sta...

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Problems solved by technology

Among them, the acoustic gas invasion detection method uses the obvious difference in wave velocity of the sound wave in the gas-liquid two-phase to monitor the gas invasion early. Although this method can realize the early monitoring of the gas invasion, the sound wave propagates through the drill pipe and the fluid in the annulus. , the external noise and other factors have a great impact on the monitoring results due to the long process, there are large errors and instability, and it is difficult to analyze the degree of gas invasion at the bottom of the well

In order to achieve more accurate early monitoring of air intrusion, some scholars proposed to use ultrasonic Doppler flowmeter to monitor air intrusion at the riser. However, ultrasonic Doppler flowmeter is based on the reflection of ultrasonic waves by solid particles or bubbles in the fluid. If the frequency difference is generated to approximate the fluid velocity (it is considered that the solid phase particles or bubbles are consistent with the fluid velocity), the measurement result reflects the velocity of the solid phase particles and bubbles, and only the fluid velocity in the information window area can be measured. Although the measurement result Gas intrusion can be detected qualitatively, but its accuracy is not high, and it cannot fully reflect the gas content in the annular space, so this method needs to be further improved

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