Theoretical And Practical Research On Long-Horizontal Horizontal Hole Clean

With the increase of energy demand and the development of energy extraction technology,horizontal wells and extended-reach wells have been widely used in the exploitation of oceans,deep formations and unconventional oil and gas reservoirs,but they have also been used in the drilling of long horizontal wells.The issue of cleaning,optimization of hydraulic parameters,and prediction and improvement of hydraulic extension capacity have become increasingly prominent and have received widespread attention.During the drilling process,cuttings in the horizontal section are easily deposited on the lower side of the wellbore to form a bed of cuttings.Due to drilling problems such as stuck drilling,loss,and high friction torque caused by poor boreholes in the wellbore,not only directly increases drilling costs and risks.It also limits the extension ability of horizontal wells and reduces the drilling speed.Wellbore cleaning tools are one of the most effective techniques for removing debris beds from wells with complex structures.This paper investigates the types of wellbore cleaning tools,rock removal mechanisms,and their application in major oilfields.The results show that although wellbore cleaning tools can accelerate rock debris migration and formation of broken rock debris beds,but because of its single rock cleaning,The series size is not complete,it is difficult to run the tool under the conditions of small wellbore.Therefore,the paper focuses on the prediction of critical flow velocity for cuttings migration in horizontal wellbore,the evaluation method of wellbore cleanliness,and the simulation of cuttings migration.The conclusions obtained by the above methods are applied in the visualization experiments of cuttings migration to optimize the later drilling process was applied to the field experimental wells to achieve the effect of cleaning the cuttings bed.First,referring to the mathematical model for evaluating the cleanliness of the wellbore in recent years,use MATLAB software to write the calculation model results.Combined with FLUENT finite element software to establish a numerical model,through iterative calculation,the finite element results are obtained and compared with the mathematical model results to obtain a set of more accurate theoretical values.Secondly,the accuracy of the results of the indoor visualization experiment is verified.Before the experiment,the dimensional analysis method is used to determine the drilling parameters that affect the experimental effect.The experiment is performed in combination with the given parameter range to reduce the experimental cost.Finally,according to the comprehensive comparison between the experimental results and theoretical results,the theory of wellbore cleanliness E was obtained and applied in the Mahu block of Xinjiang Oilfield.By observing the degree of supporting pressure during the directional operation,the number of times of lifting resistance,and the friction of the casing Resistance and casing running time to determine the feasibility of E-theory of wellbore cleaning.