A Technological & Technical Research Of Coiled Tubing Sidetracking

Coiled Tubing(CT) also called flexible pipe,it is made up of a number of length in the hundreds of meters or more flexible pipes by butt welding or inclined welding welded together without joint coiled tubing. Its length can be according to the needs of operation, from hundreds of meters to thousands meters. The relevant work of coiled tubing equipment called a coiled tubing unite. Coiled tubing drilling technology is the use of coiled tubing rig and matching downhole tools operation to the exploration and development for oil and gas Wells. Now, many oilfield has entered the late development of the world, especially in our country most of the mainland oilfield has entered high water cut stage, production fell sharply, due to the development of drilling technology and equipment constraints, there are quite a part of low permeability reservoirs and special reservoirs are not comprehensive development, And its advantages determines the CTD technology, it is a good way to solve this kind of problem.CTD is the use of coiled tubing instead of the conventional drill pipe drilling tools for drilling operation. Coiled tubing itself has no connection、no variable diameter can bend、straight up under、dynamic sealing、high strength, pressure、 small volume and convenient shipment, etc. In the process of drilling hole does not need to stop the pump, can realize the continuous cycle of drilling fluid, improve the safety of tripping speed and operation, reduce the time of tripping, shorten the drilling cycle. Especially the old well reentrant deepen or window sidetracking, not only can greatly save the drilling cost. At the same time also to discovery and exploitation of new reserves, to help the old oilfield stable production, to improve the ultimate recovery, to increase the profit of the oil field. At the same time CTD for slim-hole technology, underbalanced drilling. For low pressure easy leakage layer drilling, can be negative pressure drilling, safe and convenient to improve the success rate of drilling; For water sensitive fragile formation, CTD can use nitrogen drilling, oil-based drilling fluid, drilling and other methods, for coalbed gas and shale gas and other special gas reservoir development to provide a safe and reliable drilling technology.Combined with the significant professional project of the National Science and Technology (task 6 of project 36) "The coiled tubing equipment and the application of technology" research the process for coiled tubing sidetracking. In view of the coiled tubing window sidetracking technology were studied. Research results can be used for guiding the scene of the coiled tubing drilling test, And preliminary form adapted to the study of coiled tubing drilling sidetracking technology in China, making a little contribution to the development and improvement of coiled tubing drilling technology. This article are mainly studied from the following aspects:(1) Articles of coiled tubing drilling equipment and tools required for summary, and introduced the important function of equipment and tools and technical parameters in detail. Due to computed tomography (CT) in each assignment will be three times in the process of bending, tensile stress of the mutual alternating, it is easy to cause the tiredness of the CT, shorten service life, this fatigue failure belongs to the low cycle fatigue. The related experimental data show, CT of fatigue cycles depends not only on the size and radius of curvature of the CT itself, but also higher internal pressure will greatly reduce the cycle of CT number.(2) By studying the principle of hydraulic pressure, hydraulic energy into hydraulic pressure converter pushed down calculation model, calculate during sidetracking, bit wob in theory.(3) Through the study of rock fragmentation mechanism of PDC bit, established the physical model to simulate the static bit the stress of the rock fragmentation process, Presents a small size bit (Φ118) construction parameters.(4) Analysis summarizes all underground work of coiled tubing drilling tool combination, and explanated the main tool in detailed. Recommended BHA for old well sidetracking. Check the strength of the whole CT drill string, the stress analysis was carried out on the dangerous point, The calculation results show that, considering from the drill string yield strength itself, job security is high.(5) Fluid mechanics properties of coiled tubing is studied, established a coiled tubing operation friction pressure drop model, calculated the ground manifold (the roller pressure drop), borehole pressure drop, BHA pressure drop. In the premise of clearing debris and borehole wall stability, combined with the small size of screw drilling tools and drilling pump technology parameters. Presented the pump displacement and cyclic total pressure loss.