Study On Initiation And Migration Of Particles On Cuttings Bed In Horizontal Wells

In this paper,the cuttings startup model is divided into two categories,namely the stable cuttings migration model and the unsteady cuttings migration model.When studying the stable debris transport model,the annular flow velocity distribution law and the boundary layer flow theory are used to investigate the critical flow velocity of the drilling fluid erosion rock bed when the horizontal well is large and the horizontal well is drilled;for the unstable rock The debris migration model is based on the simulation idea of ??the two-fluid model,and the finite volume method is used to simulate the annulus flow containing cuttings.Based on the force analysis of the bed debris and the assumption of the boundary layer flow,combined with the mathematical derivation,the analytical formula of the surface shear force of the cuttings on the bed surface of the cuttings bed is obtained,and the critical startup analysis of the bed surface of the cuttings bed is established.The model is used to simulate the critical flow velocity prediction value through programming language.The large displacement of the cuttings bed surface and the cuttings of the cuttings bed are designed.The starting flow velocity is compared with the predicted value of the model.The results of model calculation and experimental data show that under different well angles and particle size conditions,the absolute average error of the critical starting flow rate predicted by the model when the circulating medium is clear water and the experimental data does not exceed 8.80%,and the circulating medium is absolute for the PAC solution.The average error is between 2.51% and 7.06%.It is known that the boundary layer flow and the annulus velocity distribution are important factors influencing the critical starting velocity of the cuttings.In order to make up for the stable cuttings migration model,it is impossible to understand the migration of cuttings and cuttings in the horizontal section,and the derivation and simulation of the transient cuttings model is carried out.Using the finite volume method,the horizontal well segments are equally meshed,and after initial conditions and boundary conditions are determined,the cuttings flow parameters in each grid are calculated at each time interval,and the data between the calculation grids is interpolated.Has a clear physical meaning.Through simulation,the migration state of cuttings and cuttings beds in horizontal well sections at any time can be obtained,so as to determine the migration law of cuttings in the whole section.The model can provide some guidance for the wellbore cleaning pump displacement setting and prediction in the field,thus improving the efficiency of wellbore cleaning.