Research On Sand Carrying Rule Of Foam Fluid In Annulus Of Wells

Nowadays,most of oil fields have been nearly in its finished period in China.The accumulated sands in the well should be cleaned for lower oil pressure and the large amounts of sands in the well.Foam fluid has gradually taken place of the pure water conventional sand flushing fluid,because of its capacity of carrying sands,low viscosity and low loss of sands which is useful in cleaning the sands in oil wells.However,foam fluid is complex dispersed system,and the temperature,pressure can influence its properties heavily.So we need to have a systematic and deep research on the foam fluid.In this article,we use the comprehensive experiment system of foam fluid which designed and built by ourselves and discrete phase model on FLUENT software to figure out the discipline of foam fluid carrying sands in annular pipes.We got the results by analysis the annular pipe's angle,the velocity of foam fluid,the diameter of sand and other factors which have an influence on sand carrying,and we also analysis the rheological characteristics of foam fluid and its movement orbits in well.The dates we got can be used in cleaning sands with foam fluid in oil fields.The results show that the foam is a power-law fluid with shear thinning when the mass of foam is between 50% and 80%.The rheological equation of foam fluid is obtained by fitting,and it is found that the bigger the foam mass is,the greater the viscosity and sand carrying capacity of foam fluid is,at the same time the non-Newtonian fluid characteristics is more obvious.The disturbance to the sand deposit in the well bottom is more violent when the fluid with higher foam mass and the sand is more easily to be carried out of the well.With the increase of the annulus angle,the sand-carrying capacity of foam fluid decrease firstly and then increase after the inflection point in 45° where the sands are most uneasily to be carried out.The larger the sand diameter is,the more difficult the sands to be carried out of the well.The bigger flow velocity is helpful to improve the sand carrying capacity of foam.However,the sand with a smaller diameter are less affected by the flow rate because of the different movement modes.The sand carrying capacity of foam fluid can be improved by increasing the concentration of foaming agent or adding the thickener.