Application Of Vortex Flow Technology In Gas Gathering Pipeline

With the further exploitation of gas field, the number of wells located on the edge of gas field will escalate and the gathering radius will expand. In the later period of gas field exploitation, the increasing liquid production rate will give rise to hydrops in gas-gathering pipelines, which will lead to higher energy consumption as a result of increasing gathering pressure of a single well. Therefore, it’s necessary to find out a new efficient technology for long distance gas-gathering pipeline in gas production process. As a new gas gathering technology, vortex flow generate technology overcomes various disadvantages of conventional gathering technologies. It can efficiently solve the liquid loading problem in the pipelines and achieve the goal of reducing line pressure.Aiming at reducing the line pressure, the flow field in the vortex flow generator and the influence of operating factors on the pipeline after the vortex flow generator were simulated by Fluent software, based on the computational fluid dynamics (CFD) in this paper. The construction of ground vortex flow generator was studied. According to the fundamental theory of vortex flow, the attenuation characteristics of vortex intensity and the vortex generation mechanism in the pipeline were discussed. The critical liquid carrying flow model, established by the combination of critical liquid carrying flow theory and ground vertex flow theory, could serve as a theoretical underpinning for the calculation of critical liquid carrying rate. The CFD model of vortex flow generator was built by Fluent. The behavior and distribution of liquid-gas flow in the vertex flow generator under different rotary angle were obtained by simulating flow in the generator. And two methods were applied in this simulation, the Euler method and RNG k-ε turbulence model respectively. The influence of pipeline operating parameters (including rotary angle, inlet velocity and liquid holdup) on the pipeline pressure drop after the vertex flow generator were studied. On the basis of optimum rotary angle determined by numerical analysis, the ground rotary flow generator was constructed and the effect of the generator on the critical liquid carrying flow rate was studied by laboratory experiment. The production data of No.5well in the experiment were simulated by CFD. The comparison of numerical simulation and experimental results showed that the vortex strength obtained by the two methods had the same trend of decay with the maximum error of15%. which meant numerical simulation could accurately reflect the decay trend of vortex strength occurred in the experiment, also proved that using the numerical simulation method to study the regulations of vortex strength decay was correct. The ground rotary flow generator was put into field application test. The differences of the liquid production and pressure drop in the pipeline before and after the generator installation were analyzed. Numerical analysis of the rotary flow generator used by field experiment was made, and the simulation results matched the experimental results with a high degree which meant the numerical simulation method was effective.The results showed that rotary angle was an important parameter affecting the performance of ground vortex flow generator. The optimal rotation angle of vortex flow generator should be45°in the condition of this experiment. As the vertex in the pipeline present exponential decay, the critical liquid carrying flow rate in the pipeline declined after the fluid flows through the generator. The generator could raise the liquid production and decrease the gathering pressure drop efficiently. Comparison between the field experiment and numerical simulation showed that there was an acceptable error in the simulation, which verified the rationality and correctness of the numerical simulation.