A gas kick early detection method outside riser based on Doppler ultrasonic wave during deepwater drilling

The feasibility of gas kick early detection outside the riser was analyzed based on gas-liquid multiphase flow theory.Then an experimental platform for gas kick early detection based on Doppler ultrasonic wave was established and the propagation experiments in two-phase flow of gas-water(sucrose solutions)were conducted.The time and frequency domains of the Doppler ultrasonic wave signals during the experiments were analyzed.The results show that:(1)No matter the pump was on or off,the detected average Doppler ultrasonic signal voltage increased first and then decreased with the increase of the gas void fraction,and had a quadratic function relation with gas void fraction,so the average voltage change of the monitored signals can be used to deduce the approximate gas void fraction.The Doppler ultrasonic wave signal voltage was significantly reduced in magnitude and variation in the solution with higher viscosity,and the viscosity has stronger impact on the magnitude of signal than density.(2)When the pump was stopped,the Doppler shift increased with the increase of gas void fraction,and the two showed a nearly linear relation,so the detected amount of Doppler shift can reflect the variation of gas void fraction quantitatively.When the pump was on,the sound energy produced by frequency converter had a more significant impact on amplitude spectrum than gas void fraction,so it is impossible to determine whether gas kick occurs by frequency domain signal analysis.(3)This method is a non-contact measurement,with no contact with the drilling fluid and no disruption to the drilling operation.It can quantitatively characterize the gas void fraction according to the change of Doppler ultrasonic signal,enabling earlier detection of gas kick.

Simultaneous measurement of velocity profile and liquid film thickness in horizontal gas–liquid slug flow by using ultrasonic Doppler method

Horizontal gas-liquid two-phase flows widely exist in chemical engineering,oil/gas production and other important industrial processes.Slug flow pattern is the main form of horizontal gas-liquid flows and characterized by intermittent motion of film region and slug region.This work aims to develop the ultrasonic Doppler method to realize the simultaneous measurement of the velocity profile and liquid film thickness of slug flow.A single-frequency single-channel transducer is adopted in the design of the field-programmable gate array based ultrasonic Doppler system.A multiple echo repetition technology is used to improve the temporal-spatial resolution for the velocity profile.An experiment of horizontal gas-liquid two-phase flow is implemented in an acrylic pipe with an inner diameter of 20 mm.Considering the aerated characteristics of the liquid slug,slug flow is divided into low-aerated slug flow,high-aerated slug flow and pseudo slug flow.The temporal-spatial velocity distributions of the three kinds of slug flows are reconstructed by using the ultrasonic velocity profile measurement.The evolution characteristics of the average velocity profile in slug flows are investigated.A novel method is proposed to derive the liquid film thickness based on the instantaneous velocity profile.The liquid film thickness can be effectively measured by detecting the position and the size of the bubbles nearly below the elongated gas bubble.Compared with the time of flight method,the film thickness measured by the Doppler system shows a higher accuracy as a bubble layer occurs in the film region.The effect of the gas distribution on the film thickness is uncovered in three kinds of slug flows.

APPROACH OF IMPROVING PRECISION IN ULTRASONIC DOPPLER BLOODSTREAM SPEED MEASUREMENT BY CHAOS-BASED FREQUENCY DETECTING

It is critical for cerebral vascular disease diagnosis through Doppler to detect the maximum and the minimum of the carotid blood flow speed accurately. A kind of Duffing system under an external periodic power with dump is introduced in the letter, numerical analysis is carried out by four-order Runge-Kutta method. An oscillator array is designed according to the frequency of the ultrasonic wave. When the external signals are inputted, computational algorithm is used to scan the array in turn and analyze the result, and the frequency can be determined. Based on the methods above, detecting the carotid blood flow speed accurately is realized. The Signal-to-Noise Ratio (SNR) of-20.23dB is obtained by the result of experiments. In conclusion, the SNR has been improved and the precision of the measured bloodstream speed has been increased, which can be 0.069% to 0.13%.

Experimental Study of Liquid Metal Flow for the Development of a Contact-Less Control Technique

The article presents an experimental study on the flow of an eutectic gallium alloy in a cylindrical cell,which is placed in an alternating magnetic field.The magnetic field is generated by a coil connected to an alternating current source.The coil is located at a fixed height in such a way that its plane is perpendicular to the gravity vector,which in turn is parallel to the axis of the cylinder.The position of the cylinder can vary in height with respect to the coil.The forced flow of the considered electrically conductive liquid is generated due to the action of the localized electromagnetic force.It is assumed that under the action of the alternating magnetic field,the liquid is heated uniformly,and the resulting heat is quickly absorbed by the forced flow,so that liquid free convection can be neglected.The experiment is carried out using an ultrasonic Doppler anemometer.One transducer is installed in the axially located cylinder sluice and the other transducer is placed in the near-wall region.According to the results,a velocity profile,corresponding to a two-tori flow pattern can be hardly obtained in the low frequency range of the power supply.However,this is possible in the high frequency range.The average velocity profiles depend essentially on the location of the coil relative to the cell.The spectral analysis of velocity signals shows that the amplitude of the velocity pulsations is comparable to the average value of the flow velocity.Such experimental results and their verification through comparison with numerical calculations are intended to support the development of new methods for reducing the intensity of vortex flows during the electromagnetic separation of impurities through an electromagnetic induction mechanism(able to produce an electromotive force that displaces particles).

Portal vein pulsatility index is a more important indicator than congestion index in the clinical evaluation of right heart function

AIM： To study the changes of portal blood flow in congestive heart failure. METHODS： We studied the congestion index （CI） and portal vein pulsatility index （PI） in patients with varied degrees of congestive heart failure using ultrasonic Doppler. Ten patients with mean right atrial pressure （RA） 〈10 mmHg were classified as group 1 and the remaining 10 patients with RA〉 10 mmHg as group 2. RESULTS： There were no difference on cardiac index （HI, P= 0.28）, aortic pressure （AO, P= 0.78）, left ventricular end-diastolic pressure （LVED, P=0.06）, maximum portal blood velocity （Vmax, P= 0.17）, mean portal blood velocity （Vmean, P=0.15） and portal blood flow volume （PBF, P= 0.95） between the two groups. Group 2 patients had higher pulmonary wedge pressure （PW, 29.9 ± 9.3 mmHg vs 14.6±7.3 mmHg, P=0.002）, pulmonary arterial pressure （PA, 46.3± 13.2 mmHg vs 25.0±8.2 mmHg, P=0.004）, RA （17.5±5.7 mmHg vs 4.7±2.4 mmHg, P〈 0.001）, right ventricular end-diastolic pressure （RVED, 18.3±5.6 mmHg vs 6.4±2.7 mmHg, P〈0.001）, CI （8.7±2.4 vs 5.8± 1.2, P=0.03）, and PI （87.8±32.3% vs 27.0±7.4%, P〈0.001） than Group 1. CI was correlated with PI （P〈0.001）, PW （P〈0.001）, PA （P〈0.001）, RA （P=0.043）, RVED （P=0.005）, HI （P〈0.001）, AO （P〈0.001）, CO （P〈0.001）, LVED （P〈0.001）, Vmax （P〈0.001）, Vmax （P〈0.001）, cross-sectional area of the main portal vein （P〈0.001） and PBF （P〈0.001）. CI could be as high as 8.3 in patients with RA〈 10 mmHg and as low as 5.9 in those with RA≥10 mmHg.CONCLUSION： Our data show that RI is a more significant indicator than CI in the clinical evaluation of high RA≥ 10 mmHg, whereas CI is better than PI in the assessment of left heart function.

Effect of Chinese Drugs for Supplementing Qi,Nourishing Yin and Activating Blood Circulation on Myocardial Perfusion in Patients with Acute Myocardial Infarction after Revascularization

Objective:To observe the effects of Chinese drugs for supplementing qi,nourishing yin and activating blood circulation on the myocardial perfusion in acute myocardial infarction(AMI) patients after revascularization.Methods:Eighty patients with anterior or inferior ventricular wall AMI,who had received revascularization by intravenous thrombolysis or coronary bypass,were randomized into the treated group and the control group equally,both treated with conventional Western medical treatment,but combined,resp...

Hydrodynamic Behavior of Three-Phase Airlift Loop Slurry Reactor

A novel fiber optic probe system and a set of commercial ultrasonic Doppler velocimeters have been used to study the hydrodynamic behavior of a three phase airlift loop (TPAL) slurry reactor. Experiments have been carried out in a loop reactor with 100 mm inner diameter and 2.5 m height, in which air, tap water and silica gel particles are used as the gas, liquid and solid phase, respectively. The radial profile of gas holdup, bubble size, bubble rising velocity, liquid circulating velocity, and the influence of the main operating conditions such as superficial gas velocity and solids concentration have been studied experimentally in the TPAL slurry reactor. The experimental results show that the bubble characteristics are different in various flow regimes and the radial profiles of some hydrodynamic parameters in the TPAL slurry reactor are more uniform than those in traditional three phase reactors. The distribution of the bubble size and bubble rising velocity can be described by a lognormal function. The influence of superficial gas velocity on the hydrodynamic parameters is more remarkable than that of the solids concentration.