Study On Horizontal Section Extension Ability Of Horizontal Wells

Horizontal well is widely used as a kind of economic and effective drilling method all over the word, the success of drilling horizontal well is a result of many factors which include equipment ability and well drilling technology But,the extended ability of horizontal well is restricted by many factors. The paper attempts to study extended limit of horizontal well which can provide certain theoretical guidance for predicting future drilling performance, engineering design and reducing drilling risk.The paper analyzed drill string mechanics of horizontal well, giving up the assumption of rigid wall in traditional torque and drag model, establish the new model which considered the subgrade reaction force and treat the horizontal as semi-infinite long beam,obtain the curve of differential equation under the influence of subgrade reaction force.In order to predict drilling extenxsion accurately before drilling, The paper calculated the mechanical extension limit and hydraulic extension limit of two terms.For the hrdraulic extension limit of horizontal well, mainly analyzed the effects of formation factors, drilling pimp capacity and circulate pressure loss on extension limit.and assesss the ability of horizontal wellbores hydyaulic extension in gas field in Central Tarim,The evaluation method of horizontal well is calculate the drilling mechanical extension limit and hrdraulic extension limit, then check the extension limit ensure the security of the drill string strength, compare the hydraulic extension limit with mechanical limit, the minimum value is the horizontal well extension limit.The paper analyzed the exetension of large displacement horizontal well, not only involves the mechanics analysis, but also involves the torque and drag calculation under complex conditions.The studies in paper can provide theoretical reference for extended ability in large displacement horizontal well,and has important guiding significant for stretching the drilling limit of large displacement horizontal well.