The Design Research And Application Of The Downhole Gas-liquid Helix Separator

In some peripheral blocks of Daqing, the use of oil displacement method of CO2 injection results in the high gas-liquid ratio of wells, which has increasingly influence on the production of wells apparently, and gas is the main reason for pump efficiency reduction. One effective measure to reduce the gas in the fluid that enters into the pump is adopting downhole gas-liquid separator to separate gas from liquid before the fluid goes into pump. Therefore, the in-depth research on gas separation of downhole gas-liquid separator has significant meanings in improving the management of pumping system, enhancing the pump efficiency and improving the structure design of gas-liquid separator and other aspects.In this paper, the mechanism and efficiency of downhole gas-liquid separator are discussed, and the operating principles and structures of different types of gas-liquid separators are analyzed. According to basic theory of gas-liquid two-phase flow, combined with the techniques of conventional gas-liquid separator, the rationality of using helix separator to do downhole gas-liquid separation is confirmed. Hydraulic design calculation and laboratory experiments of helix separator are studied, based on which optimal scheme was proposed. The main structure parameters of helix gas-liquid separator are space between helix slices, inside and outside diameters of helix slice and the effective separation length. How to optimize and combine those parameters with associated devices to attain the maximum degasification efficiency is the main research target of this paper.In this paper, hydrodynamic analyses of helix separator is accomplished, and combined with the field's practical situations, the mathematical model of helix pattern of gas-liquid two-phase flow is established, and the calculation software of production system of downhole gas-liquid separation is designed. The experimental equipments used for simulating downhole gas-liquid separation was designed and built in the Special Laboratory of Northeast University of petroleum. Through laboratory experiments, the service conditions and the separation effect of gas-liquid separator were studied, and according to related theory and experiments, the optimization of separation equipment was made, which has achieved great experimental effects.Field tests were carried out in the third factory of Daqing oilfield. The pump efficiency increases separately by 14.3 and 8.7 percentage points in North 4-4-Ⅲ53 well and North 2-4-036 well. The theory research of downhole gas-liquid helix separator system and laboratory, field experiments show that applying helix separator for downhole gas-liquid separation is feasible and has a good application effect in downhole gas-liquid separation, which has a significant effect in solving the low productivity problems of gas bearing wells, and has a stable work performance and reliable operation, and also can provide basis for oilfield application of gas-liquid helix separator.