Study On Transient Migration Law Of Cuttings In Horizontal Well Section

The efficiency of drilling fluid directly affects the quality of a well.many scholars at home and abroad study the cuttings migration law in different well inclination and field practice indicate:because of the low efficiency of drilling fluid carrying rock in highly deviated and horizontal wells,annular cuttings continuously deposited to the low side of wellbore to form cuttings bed,if the cuttings bed deposited in the lower sidewall can not be cleaned and controlled in time,which will bring many serious problems,these problems mainly include: hold pump,sticking,high friction,high torque,even cause drilling tool fracture downhole safety accident,eventually even cause the entire hole scrapped,therefore,for large deviated wells and horizontal wells in high angle well section and horizontal well section,the rock carrying efficiency of drilling fluid is not only of theoretical significance but also of practical significance,therefore,this paper mainly studies the migration law of cuttings in horizontal well section,the corresponding mathematical model is also established,a lot of experiments have been done to verify the reliability of the model.Based on solid-liquid two-phase flow theory and the original stable rock carrying model,through the study of the migration rule of cutting in horizontal section,under different working conditions,the distribution of cuttings was further divided,and the mathematical model was established corresponding to different distribution,and the stability three layer model is mainly solved by programming.The definition of analogy in the sediment of the angle of repose,based on the description of the cutting motion,the cuttings bed repose angle is defined.And based on the wedge accumulation model and cuttings bed stress model,the calculation model of the repose angle of cuttings bed is established in hydrostatic condition,it provides the basis for the division of high deviated well section and horizontal well section.Study on the the position random distribution of the particle on the bed surface,the random distribution function of relative subsidence degree is established,It is also possible to establish a link between the critical flow velocity and the particle settlement,according to the probability distribution function,the quantitative relationship between the critical incipient velocity and the percentage of particles on the cuttings bed surface was established.