Numerical Calculation Of Cuttings Transportation In Inclined Borehole And Flow Field Calculation Of Cuttings Removing Tool

Cuttings transportation mechanism has been a crucial subject to the drilling of inclined wells, horizontal wells and extended reach well for a long time, therefore it makes great significance to study how to keep good condition of borehole cleaning. Based on the study of the mechanism of cuttings transportation, this paper has divided the whole well into three different sections according to the inclined angle, and they are vertical section with inclined angle from 0 to 30 degree, inclined section with inclined angle from 30 to 60 degree and high inclined section with inclined angle from 60 to 90 degree. Different models were developed according to the characteristics of different section. These models applied solid-fluid two phase flow principal, cuttings bed force balance condition, particle starting analysis and particle diffusion equation to created two-layer hydraulic model and there-layer hydraulic model.On the basis of the creation of mathematical models, this paper has developed a cuttings transportation software using VisualBasic6.0. After the inputting of drilling parameters in terms of different drilling conditions, the results of cuttings bed dimensionless height, annular cuttings concentration, minimum annular velocity and minimum pump rate can be acquired through calculation. The results have good consistency compared with the published data, so the validity of the mathematical model can be proved. The paper has also involved in the analysis of effects of single factor to the cuttings bed dimensionless height through data and graphs attained from calculation, and also the results show good consistency with the laboratory experiment and practical drilling work. Having revised the models, the paper gets the methods of calculation of minimum annular velocity and minimum pump rate, then the effects of the single factor to the minimum annular velocity has been discussed. According to the theory and practical analysis of the cuttings bed removing methods, a kind of cuttings bed removing tool has been developed. This kind of tool can be connected between the drilling pipe to help the effective removing of the bed using its hydraulic and mechanical function. Having three design plan been proposed, the velocity vector arrangement map surrounding the tool can be achieved, using SOLIDWORKS2006 and GAMBIT2.0 to model and grid the fluid zone and analyzing by FLUENT6.0. The map show satisfied results can be attained using this kind of tool to erode the cuttings bed.