Identification of gas invasion location in ultra-deep wells based on multiphase pressure wave response chart
In this study,considering the parameters of phase interface Reynolds stress,drag force,virtual mass force and gas-liquid physical property difference,a mathematical model of wellbore multiphase pressure wave velocity and pressure re-sponse was established,and a new method for identifying the location of gas invasion in ultra-deep wells was proposed based on the uniqueness of the multiphase pressure wave response chart in the wells.In consideration of the boundary parameters,such as wellhead gas overflow rate,backpressure and drilling fluid density,the solution of the model was programed using a differential mathematical method.The new method was verified using the data from an ultra-deep well YS1(8680 m),with the pressure response error less than 1.703 s,and the calculation and measurement error less than 6.15%for predicting the gas invasion location.The results show that,with the increase of the backpressure,the compressibility of wellbore fluid de-creases the velocity of wellbore pressure wave increases and the pressure response time decreases.With the increase of the wellhead gas flow rate,the annulus void ratio increases,the pressure wave velocity decreases and the wellbore pressure re-sponse time will be prolonged.For instance,when the wellhead gas flow changes from 0.83 L/min to 38.33 L/min,the pressure response time at 8680 m of the bottom hole can be increased by 261.83%,from 10.127 s to 36.643 s.The results of gas invasion location identification not only depend on the accuracy of wellhead pressure and flow sensors,but also on the calculation accuracy of the pressure wave response chart.This study has proved that identifying the gas invasion location in ultra-deep wells by means of the pressure wave response chart is feasible.
国家科技期刊平台
NSTL
万方数据
维普
