| At present,liquid loading is common in the middle and late stages of production of horizontal gas wells in Su14 block of Sulige gas field,which seriously affects the productivity of gas wells.In order to reveal the law of liquid loading in horizontal gas wells,reduce the decline rate of gas wells,improve the efficiency of drainage gas recovery measures,this paper conducts indoor simulation experiments and numerical simulation studies on the characteristics of liquid loading in horizontal wells.On this basis,the simulation and effect evaluation of foam drainage gas production and plunger gas lift measures in horizontal gas wells are completed,the following understandings are obtained:(1)By analyzing the production law of horizontal wells in Su14 block,the production data of 12 horizontal gas wells are selected as the representative to study the production performance and gas-water distribution of horizontal gas wells in Su14 block.According to the well structure characteristics of gas wells,the indoor experimental model is constructed,and the simulation experiment of gas-liquid two-phase flow in visual horizontal wells is carried out.Based on the numerical simulation method,the gas-liquid two-phase flow model of horizontal wellbore is established,and the influence of different wellbore structures and fluid properties on liquid loading in horizontal wells is analyzed.The results show that when the gas production is less than 2.5×10~4 m~3/d,the pressure drop and liquid holdup in the inclined section are obviously changed,the liquid phase slippage loss is serious,the flow pattern is slug flow and churn flow,and there is effusion in the horizontal wellbore.With the increase of liquid-gas ratio and fluctuation angle of horizontal section,the pressure drop and liquid holdup of horizontal well increase,and the degree of liquid accumulation is more serious.The energy loss is mainly at each peak of gas-liquid two-phase crossing,and the liquid accumulates at the uphill and bottom trough of horizontal section.(2)Based on the study of the mechanism of foam drainage gas production,a pressure drop model of foam drainage in horizontal wells considering wellbore flow pattern and wellbore structure is established.Fluent software is used to simulate the foam drainage gas production measures in horizontal wells,and a wellbore lifting flow model is constructed.The wellbore pressure drop and liquid carrying situation of foam drainage agent under different depths and mass fractions are analyzed,so as to optimize and evaluate the foam drainage gas production measures.The results show that when the foam drainage agent is put into the middle of the horizontal section,the liquid carrying capacity in the middle of the inclined section and the middle of the vertical section is increased by 15.98%and 32.86%respectively,and the average wellbore pressure drop is reduced by 6.31%and 27.51%respectively,which effectively alleviates the degree of wellbore effusion.When the gas production is about 2.5×10~4 m~3/d,a better foaming effect can be achieved,and the optimal foaming agent mass fraction in the simulation range is 0.3%.(3)Based on the study of the mechanism of plunger gas lift measures,the numerical simulation of plunger gas lift measures in horizontal wells is carried out by using Fluent software.The wellbore lifting flow model is constructed to analyze the liquid carrying effect under different plunger depth and different plunger equipment parameters,so as to optimize and evaluate the plunger gas lift measures.The results show that when the plunger is lowered into the middle of the horizontal section,the proportion of liquid leakage is only 2.7%,which is beneficial to the discharge of liquid accumulation in the horizontal section.The best time to implement plunger gas lift measures is before the gas production drops to 1.5×10~4 m~3/d.The optimal upward velocity of the plunger in the simulation range is 5 m/s,and the optimal turbulence groove depth is 6 mm and the width is 20 mm.The research results of this paper can deepen the understanding of the law of liquid loading in horizontal wells,and have certain guiding significance for the efficient development of horizontal gas wells,and provide reference for the formation of well selection technology for drainage gas recovery measures in horizontal gas wells in Su14 block. |
