Abstract
Based on field data and the related theories, the effects of drill string length, rotation speed, trajectory, and drilling fluid density on the friction during horizontal well drilling are analyzed in Sichuan. With increasing the length of drill string in the horizontal section, the friction grows. The drill pipe rotates faster and the torque decreases. Large undulation of borehole deviation and the “W” shape of the horizontal section lead to excessive friction. A higher fluid density causes higher torque and drag. Moreover, a friction reduction tool is designed to reduce friction, decrease the wear between the casing and the drill pipe joint, and prevent the differential pressure sticking, which improves the rate of penetration, and the specially designed spiral diversion channels improve the efficiency of borehole cleaning. The field experimental results have shown that the accumulated operational time of the friction reduction tool is more than 130 h and its fatigue life reaches up to 3 × 105 cycles. A plan of improving the tool structure is proposed to reduce the mud balling after the experiment. Finally, the mathematical model of calculating the spacing of the friction reduction tools is established, which provides technical support for investigating the friction in horizontal well drilling.
Highlights
Parts of reservoirs in the oil and gas fields in Sichuan, China are characterized by deep burial, tight lithology, low porosity and permeability, big contribution of fracture to productivity, and big difficulty in reserves exploitation
Considering the above problems, the factors affecting the friction during horizontal well drilling are analyzed in Sichuan, and a new friction reduction tool is developed for horizontal well drilling, which reduces the torque and drag and provides supports for improving the extension capability of drill string in the long horizontal section
A new tool for reducing torque and drag in horizontal well drilling has been developed in this study
Summary
Parts of reservoirs in the oil and gas fields in Sichuan, China are characterized by deep burial, tight lithology, low porosity and permeability, big contribution of fracture to productivity, and big difficulty in reserves exploitation. The friction is a factor restricting directional angle build-up and horizontal section extension, improving drilling time efficiency, and decreasing drilling costs, especially in high-pressure tight reservoirs.[6,7,8]. Considering the above problems, the factors affecting the friction during horizontal well drilling are analyzed in Sichuan, and a new friction reduction tool is developed for horizontal well drilling, which reduces the torque and drag and provides supports for improving the extension capability of drill string in the long horizontal section. The reason is that increasing the drilling fluid density requires a higher solid content, which increases the filter cake thickness and the friction coefficient of the filter cake, resulting in viscous drill string sticking. A new tool for reducing torque and drag in horizontal well drilling has been developed in this study
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