High temperature and corrosion resistant materials like Inconel 718 is often used for drill collars to shield these sensitive communication equipment from the hostile downhole environment. These deep holes are fabricated in drill collars to deploy delicate sensors downhole for obtaining vital information like temperature, pressure and other geo-physical data from the bottom of the hole.

The method to reduce straightness deviation by controlling support clearance is proposed and verified by experiments.Īpplication of deep holes is extensively found in the oil and gas industry to manufacture downhole equipment. In this paper, the influence of support clearance, support spacing, support stiffness, axial force, and drill pipe stiffness on straightness error is analyzed through simulation and experiments. Based on the analysis of influencing factors of straightness deviation of gun drilling, this paper establishes the theoretical model of the straightness error of the middle four supports by using the Euler-Bernoulli beam theory and reveals the relationship between the bit deflection and the deviation of the hole axis. In addition, the current theoretical model of straightness deviation is inconsistent with the actual working condition of long and deep hole gun drilling, so the prediction of straightness error is still a difficulty in deep hole machining. As an important hole processing technology, the gun drill has a complex structure and weak relative stiffness, which makes it difficult to avoid the straightness deviation of the hole. The method to reduce straightness deviation by controlling support clearance is proposed and verified by experiments.ĭeep-hole drilling (depth-diameter ratio > 10) accounts for about 40% of hole processing. Based on the analysis of influencing factors of straightness deviation of gun drilling, this paper establishes the theoretical model of the straightness error of the middle four supports by using the Euler–Bernoulli beam theory and reveals the relationship between the bit deflection and the deviation of the hole axis. Also, the current theoretical model of straightness deviation is inconsistent with the actual working condition of deep hole gun drilling, so the prediction of straightness error is still tricky in deep hole machining. Deep-hole drilling (depth-diameter ratio > 10) accounts for about 40% of hole processing.

Gun drill cutting parameters