氮气驱地面注入分气阀压力损失规律研究OA

In response to the development challenges of low-permeability oil reservoirs,such as poor water flooding effect,high injection pressure,and low recovery rate,nitrogen flooding as an efficient,low-cost,and environmentally friendly technology for enhancing recovery,has received extensive attention.However,in field applications,there are differences in permeability among different wells,and the independent regulation of single-well flow rate is the key to improving reservoir development efficiency.To achieve precise control of nitrogen flooding injection flow rate in low-permeability oil reservoirs under the condition of shared gas sources among multiple wells,and to solve the problems of unclear pressure loss laws of the valve and the reliance on experience for single-well flow rate regulation,this paper starts from the ground gas injection process,based on engineering thermodynamics theory and gas throttling equations,combined with the Van der Waals non-ideal gas state equation,calculates the physical parameters of high-pressure nitrogen,establishes a throttling calculation model for high-pressure nitrogen passing through the valve,the relationship between the throttling flow area of the valve,injection temperature,injection flow rate and pressure loss,and constructs a pressure loss chart of the valve.The numerical simulation results show that within the commonly used engineering conditions,the square root of the valve pressure loss is approximately linear with the injection flow rate,and the equivalent pressure loss method can be used to achieve quantitative allocation of injection for wells with different permeabilities.For the fluctuations of gas pressure and temperature in the pipeline during injection,a sensitivity analysis of valve pressure loss was conducted,and a sensitivity analysis chart is obtained.According to the chart,it can be known that the valve pressure loss fluctuates within 8%when the environmental temperature fluctuates;when the valve inlet gas source pressure fluctuates within±0.5 MPa,the pressure loss changes by approximately 3%.The sensitivity analysis conclusion of the valve indicates that within the common environmental temperature fluctuations and compressor pressure fluctuations,the pressure loss change amplitude is small,which shows that the valve parameters determined based on this model have good stability and reliability in the field and can meet the requirements of actual engineering operation.This research provides theoretical support and engineering reference for the process optimization and field operation of the high-pressure nitrogen flooding injection system,and is of great significance for improving the gas injection development efficiency of low-permeability oil reservoirs.