The Impact Of Eccentricity On Annular Multiphase Flow In Aerated Drilling

In the past two decades, aerated drilling has been applied to improve recovery of the lowpermeability oil and gas reservoirs at home and abroad. This technology can improve thelevel of exploration and development, reduce the cost of drilling and protect reservoir.Because of its advantages, aerated drilling has been developed and promoted rapidly. Andits theoretical study has also been further developed.In this paper, the impact of the eccentric drill string to annular multiphase fluid inaerated drilling was studied. Based on mathematical solution of eccentric annuli, combinedwith multiphase flow control equations and flow law, aerated drilling eccentric annuluspressure formula was derived. Under the condition of Concentricity and different degrees ofeccentricity, the annulus fluid parameters were calculated and with CFD. The distribution lawof each parameter with depth and the influence law of the eccentricity to each parameter wereanalyzed. The annulus pressure of aerated drilling with injection gas volume, injection fluidvolume and wellhead back pressure were discussed. Compared with CFD simulation results,calculation results is consistent with the software simulation. It is proved that the model,solution and calculation results are reliable.