Study On Steady State Calculation Of Submarine Oil-Gas Pipeline Network And Its Software Development

With the gradual transfer of oil and gas exploitation to the deep sea,demand for off-line simulation of oil-gas transportation pipeline network in submarine gathering and transportation system is greatly increased.The flow of fluid in the pipeline is more complicated and changeable with complex environment of the seafloor and the changes of pressure and temperature.Therefore,it is very important to study the variation of flow parameters of submarine oil and gas gathering and transportation network.In this thesis,the theoretical analysis and programming practice are carried out in the aspects of single pipe flow model,pipe network algorithm and solution based on the calculation demand of steady hydrothermal simulation of oil-gas transportation pipeline network.On the basis of this,the calculation software of oil-gas transportation pipeline network MPF is developed.Theoretically,this paper firstly integrates the code of the existing single-pipe gas-liquid two-phase flow model and its variants,so as to facilitate the invocation of pipeline network calculation.In the calculation of pipeline network,the structure of pipeline network is represented by graph theory,the mathematical model of pipeline network is established by node equation,and the nonlinear equations are solved by Newton-Raphson method.In the calculation of pipe network temperature,node temperature is calculated according to thermodynamic equilibrium.The hydraulic and thermal forces of the pipe network are solved by coupling iteration.In the calculation process,variable damping coefficient is introduced to reduce the sensitivity of Newton-Raphson method to initial value which improves the stability of the algorithm.The calculation software for oil-gas transportation pipeline network MPF was developed based on theoretical research.The software realizes the steady-state solution function of the pipeline network and builds a friendly user interface.Comparing the results of software calculation with commercial software,the results show that the error of software calculation is very small,which verifies the applicability of the software.When the software is applied to a practical operating condition in the field,the error between the calculated results and the measured results is less than 2%,which verifies the reliability of MPF in the calculation of oil-gas transportation pipeline network.