The Effect Of Pipeline Structure On Severe Slugging Flow Characteristics

Gas-liquid two-phase and multiphase slug flow is commonly encountered in crude oil and gas multiphase wells and pipelines, boiler tubes and heat exchangers, and severe slugging is frequently found in multiphase transport system of offshore petroleum industries. Detailed research of the hydrodynamic characteristics of these flow regimes is of theoretical and practical importance. However, available experimental data from large test facility and corresponding theoretical analysis and numerical model are seldom reported presently.The inner diameter of test pipe is 0.051m. In this study, the severe slugging phenomena in horizontal-decline-riser test pipe, and incline-riser test pipe were studied systematically. The mechanism and flow characteristics of severe slugging phenomenon were analyzed. And according with decline-riser test pipe with addition gas volume, the main contents and conclusions are as follows:It is found that in the text pipe with addition gas volume, the space of the addition gas volume is obviously bigger than the gas accumulation space of real text pipe. In a period of time, the gas can not flow along the decline pipe downwards, but flow into buffer tank through the entrance. It is more easily to achieve gas-liquid separation,stratification, so that the accumulation of gas in the buffer tank. The liquid is formed in the decline pipe. It verified that in the forepart of the riser pipe gas-liquid stratified accumulation is one of the necessary conditions.The horizontal–declined-riser pipe and declined-riser pipe with gas accumulation volume were studied and compared. It is found that the occurrence of severe slugging happened in declined-riser pipe with gas accumulation volume is larger than the experimental region. But the occurrence of the transition region is less than the experimental happen. In the studies, the upper border of the severe slugging and the transition pattern is obviously broad than this experiments, the right border of the severe slugging pattern and the transition pattern is similar with this experiments.It was found that the influences of gas superficial velocity, liquid superficial velocity and the gas volume of pipe before riser pipe on flow characteristics of severe slugging are obvious, Severe slugging phenomenon have strict period characteristic. The length of period decreases with gas superficial velocity, liquid superficial velocity increasing, logarithmic coordinates in a linear relationship. The pressure fluctuation of severe slugging depends on gas superficial velocity, liquid superficial velocity and the gas volume of pipe before riser pipe. The maximum value of pressure fluctuation occurs at the right boundary.In the horizontal-tiny inclined pipe system, the instantaneity of inclined pipe compared with horizontal pipe, it is found that in the inclined pipe, the slugging is formed by air bubble effect on the interface wave, besides, the change of the length of the slugging is from the short to the length and then weaken to the short. The distributing flow pattern in the tiny inclined-riser pipe is absolutely different from horizontal-tiny inclined pipe, the stratification phenomenon does not occur in tiny inclined pipe, and there is no severe slugging phenomenon in the combinative riser pipes.