| In the process of exploiting loose sand reservoir with horizontal wells, sand production can seriously affect the normal production of oil field and even cause safety accidents. Therefore it is necessary to clean wells regularly in addition to take some measures to prevent sand. In this paper, we deeply study the force, migration and settlement mechanism of sand in annulus of horizontal section in order to provide technical parameters for sand washing operation.We utilized CFD simulation method combined with laboratory test to study the impact of annulus flow, fluid viscosity, annulus dimension, sand characteristics, deviation angle and other factors on flow property of flow field, rules of sand bed formation and annulus pressure loss in the process of horizontal annulus flow. From the results of numerical simulation we learned that the axial velocity profile of the flow field is in the form of non-symmetrical parabola and annulus flow impacted the flow field greatest which was proportional to axial velocity value while other factors impacted relatively small.In this paper we combined PIV system with horizontal annulus pipeline system which can both measure flow state of liquid-solid two phases flow and observe the development of sand bed in annular with visualization, reliability and accuracy. Based on the force analysis of annular sand, we established sand starting model and regressed formula of sand bed deposition thickness according to the results of orthogonal test. Finally we analyzed the influence degree of each factor to the above indexes.From comprehensive analysis of the above results we found that the results of numerical simulation were consistent with the results of PIV experiments, so the method we took in this paper is feasible to study liquid-solid two phases flow and can provide assistance for sand washing technique. |
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