Optimization Design Of Hydraulic Parameters Of Extended-reach Well Based On H-B Flow Pattern

As a kind of economical and effective mining method,Extended-Reach wells are widely used at home and abroad,especially for the development of offshore oil and gas fields.However,because of the large well angle and long slope section length,and the serious eccentricity of the drill pipe,the rock debris can easily form cuttings bed in the high slope section and the horizontal well section,so it is faced with a series of technical problems.In this paper,fluid pressure simulation software is used to simulate the calculation method of annular pressure loss in Extended-Reach wells and the law of debris migration in Extended-Reach wells and the calculation formula of the critical annulus return velocity that does not produce cuttings bed,combined with cyclic pressure loss and wells.The evaluation of eye-cleaning evaluation was performed by modifying and optimizing conventional hydraulic parameter design procedures,and the hydraulic parameters of Extended-Reach wells were optimized.Using numerical simulation software to simulate the annular watershed field,and the drilling fluid was studied based on the H-B flow pattern.Firstly,the normal wellbore annulus flow field is simulated(no eccentricity and rotation of the drill string)and compared with the calculation formula of the conventional well annulus pressure consumption to verify the correctness of the simulation.Then the gradient values of the pressure drop in the annulus under different eccentricities and different speeds of rotation were obtained through simulation.By comparing and analyzing the annular pressure drop gradients of conventional wells,the eccentric influence coefficient and rotation influence factor of the annular pressure loss were obtained.The empirical formulas for calculation of the annular pressure loss under the rotation and eccentric conditions of the drill string are summarized,and verifying its correctness.By analyzing the force of the cuttings particles in Extended-Reach wells,the transportation characteristics and transportation start-up laws are obtained,and the influencing factors of cuttings transportation are analyzed.Using numerical simulation software,based on the Euler solid-liquid two-phase flow model,the law of drilling fluid carrying cutting under different conditions was simulated.It was found that the eccentricity and rotation of the drill string had no effect on the axial velocity of the drilling fluid,and had a large influence on the tangential velocity.The annular cuttings concentration under the conditions of well inclination,eccentricity,drilling fluid velocity,particle diameter,etc.,and the minimum annulus back velocity without generating cutting bed are obtained.The minimum annular annulus velocity is obtained by regression method,and indoor test to verify its correctness.Calculate and check the cycle pressure consumption of a well by using the large displacement hydraulic parameter optimization design software,and analyze the cleanliness of the well with a well angle of 50~65°;The hydraulic parameter optimization design was performed to obtain the hydraulic parameter design results under the HB model and the results were compared with the on-site construction results,which can provide a basis for the evaluation of on-site wellbore cleaning status.