Transient Simulate Study For Gas-condensate Pipeline

At present,underwater condition,the traditional technology became more and more complicated.Some complex area,such as the deep sea,desert,hinterland etc.have been exploited.Because of the risk,especially some strong transient process,such as shutoff,restarting conditions in long distance pipeline operation,so getting the real-time flow parameters is the key of the study.But considering the large difficulties and high investment,multiphase flow numerical simulation is economic way to achieve real-time flow information for assisting production.In terms of multiphase flow numerical simulating study,there are series of commercial softwaves,but domestic research is few.Now,our research group has some achievements in this field,but there are still some problems with low accuracy and slow computation speed.Based on the condition,this paper is aimed at optimizing the hydraulic algorithm to solve the existing problems.After analyzing the characteristics of multiphase flow simulation calculation,two-phase flow is selected as the model for one-dimensional long distance pipeline.In this paper,PISO algorithm of segregated solution method is conducted to use in two-phase flow.In discretization,high-resolution scheme is adopted for promoting accuracy.Through two basic examples: WATERFAUCET and SHOCK WAVE,this paper compares the differences of pressure-correction method among PISO algorithm,SIMPLEC algorithm and SIMPLE algorithm which the research group used before,and the results show that comparing with the SIMPLE algorithm and the SIMPLEC algorithm,the PISO algorithm had advantages in computing speed and accuracy.At the end of this paper,according to the online flow security system research developed by the research group,PISO algorithm is used instead of the original algorithm,and simulated on two practical natural gas-condensate pipeline.In the other hand,this paper also used the coupled algorithm,TPCOMP,and commercial software,OLGA,for comparing.The results show that although the accuracy of the PISO algorithm is better than TPCOMP,it's computing speed is much slower than TPCOMP.This paper also attempts to use the multigrid method to change the time step,although the results are not very well.But it provides a basis for future research.