The Research On Wet Gas Gathering Line Liquid Distribution And Countermeasures In Dawan Block Of Puguang Gas Field

The Dawan block of Puguang gas field D405-D403 pipeline, which adopts gas-liquid mixed flow technology and contains large of H2 S, lays in complex mountainous. The fluid called liquid loading may often accumulates in the low point of pipeline, the existence of the liquid loading can reduce pipeline transmission capacity, can cause the pressure fluctuation and aggravate corrosion system. In order to solve the problem of liquid loading, iquid loading rule must be researched, and some measures for controlling and removing liquid loading must be put forward.To solve this issue, based on the two-fluid model, this paper established the effusion prediction model which is suitable to this pipeline, OLGA software is adopted to solve the model. The influences of inlet gas, inlet fluid volume, inlet temperature and environmental temperature on the liquid loading and the liquid holdup distribution is studied, and then summarize the regularity of liquid loading in D405-D403 pipeline. The result shows that:The first, there exists a saturated liquid loading quantity in tube, under the circumstances of constant operating parameters, the quantity of liquid loading is a constant. The second, when the pipe structure is settled, the quantity of liquid loading are greatly influenced by the inlet gas, and the influence of inlet fluid volume, inlet temperature and environmental temperature is smaller. The third, there exits an entrance critical gas liquid ratio, greater than which, the liquid loading in tube will keep in a low level. And the gas and liquid ratio of these two pipelines has been calculated. The forth, there are 11 pipe sections which are easy to produce liquid loading. And these sections are often“V”branches or the former two-thirds on uphill sections.Using the OLGA shutdown and starting up module to study three special working conditions. The result shows that the influence to the quantity of liquid loading in D404-D403 is greater, and the order from large to small is, D405 station shutdown bigger than D404 station shutdown bigger than two stations shutdown bigger than two stations working. And the influence to D405-D404 is smaller.Based three special working conditions, the analysis under several factors shows that big diameter and inlet gas are main control factors to the quantity of liquid loading. When the inlet gas is constant, the inlet fluid and temperature are reduce, the diameter of pipe is increase, the liquid loading will increase. And when the inlet gas and liquid volume are increase at the same time, the liquid loading will reduce.Fluid control measures and cleaning measures are put forward based on the liquid loading rules. By adjusting the inlet ratio of gas and liquid, the inlet temperature and production time, the quantity of liquid loading can be control to a low level. In order to predict the liquid loading situation, the ultrasonic detection technology and the infrared measuring technology can be used to detect the pipes with frequent liquid loading distribution. Ensure that the gas speed is greater than the smallest liquid carrying speed which is 4.68m/s. The cleaning measure is pigging, and the judgment basis are studied. Using OLGA corrosion model to calculate the corrosion rate, by which, the pigging cycle is made under the view of corrosion inhibitor cycle. Then established pigging model on the basic of liquid loading model, the pigging parameters are calculated. And the key parameters of pigging process is determined, such as the pressure drop, Pig speed, Pigging time, Push the ball capacity, the whole inlet gas volume and so on.