The Optimization Research Of Hole Cleaning Technology In Ocean Extended Reach Well

Hole cleaning technology is one of the key technologies in extended reach well,and maintaining hole cleaning is very important for safe and rapid drilling.The extended reach well has a large horizontal displacement and a long large well oblique section,during the drilling process,cuttings are easily deposited on the low side of the wellbore to form a cutting bed.Moreover,when considering the presence of risers,the migration of cuttings particles is susceptible to factors such as low temperature of the sea,ring back speed,drill string rotation,cuttings particle size and other factors.If you can't keep the hole clean,it will lead to a lot of serious problems,such as holding pump,sticking and so on,which directly affect drilling efficiency,drilling cost,wellbore quality and drilling safety.Therefore,the study of hole cleaning technology for the rapid development of marine migration wells have great guiding significance.In this paper,based on the study of the theory of cuttings migration,the optimization research of hole cleaning technology for large displacement drilling is carried out by means of numerical simulation and theoretical research.The influence factors of the migration of the wellbore cuttings were simulated and analyzed by Fluent fluid mechanics software,and the influence degree of each factor was determined.Summarizing the calculation model of the existing hole cleaning,in view of its shortcomings,a simple and practical hole cleaning model is established with the inclined section as the main research object,and the model accuracy is verified by an example.Based on the above model,Visual Basic 6.0 is used as the integrated development environment,and the prediction software of hole cleaning effect is developed,and the rationality & accuracy of the software are verified.The results show that the annulus temperature has a critical value,and when the temperature is higher than this critical value,the volume concentration of the annulus is basically unchanged;With the increase of the drilling fluid n and the k value,the volume concentration of the annulus is significantly reduced,it indicates that the rock carrying efficiency is sensitive to the rheological parameters of the drilling fluid;In all the influencing factors,the effect of annular retrograde velocity is the largest,followed by the cuttings particle size,the ring temperature and the drilling fluid n,k,and the influence of drilling fluid density and drill string rotation are weaker.On the basis of the existing calculation model,a simple and practical hole cleaning model is established by simplifying the calculation parameters,and based on the drilling parameters of 8 large displacement wells in Shengli Oilfield,the accuracy of the model is verified.