Research On Cuttings Transport Phenomenon With Foam In Annulus Of Horizontal Wells

Foam drilling is the one of main branches of underbalanced drilling. This technology use the foam as the circulating media, it has a big distinction to the traditional drilling, such as foam fluid flowing and the cuttings transport ability of foam fluid, At present,we lack of systematic theory security and experimental study. In view of this, used the method of theory research conbining with experimental verification, researched into design and calculation of foam fluid flowing and the cuttings transport ability of foam fluid, expected it can provide technical suppport to the further development and application of the foam drilling.Based on the combination of numerical simulation and simulated experiments, the effect of foam quality, annulus eccentricity, rotation of drilling pipe, and other factors on the flow properties and cuttings transport ability of foam fluid are studied with foam fluid flowing in annulus of horizontal wells. The research results on flowing characteristics of foam fluid in well annulus indicate that the density of foam decreased along the direction of foam flowing and the change of foam's density in per meter decrease with the increase of foam quality. In eccentric annulus, velocity core of foam concentrate to the wide interval in the upside of eccentric annulus and velocity of foam decrease in the narrow part which in the underside of eccentric annulus. During the study of the effect of drilling pipe rotation on flowing characteristics, it's found that the pressure difference in axial direction increases with bigger foam quality; annulus eccentricity has much influence on the offset degree and offset direction of velocity core in annulus space; with the presence of cuttings bed, the offset direction is contrary to the rotation direction of drilling pipe due to the secondary reflux of foam fluid in well annulus caused by drilling pipe rotation. The study on cuttings transport ability of foam fluid shows that the cuttings transport ability of foam fluid decreases with the increase of particle diameter of cuttings and the increase of annulus eccentricity while improves with the increase of foam quality.Using developed experimental equipment of the multifunctional annular cutting's taking. The experimental study on the effect of different factors on the flow properties and cuttings transport ability of foam fluid are studied with foam fluid flowing in annulus of horizontal wells, noted and calculated the experimental data. and took the comparison with academic value and they tallied well with each other. The results of numerical simulation are good agreement with the experiment.It is show that the research methods and technological paths in this paper are right. The result of the research perfected the basic theory of the cuttings transport of foam fluid in a deep degree, and provided support both in theory and in technology for advancing the application of foam drilling technology.