![]() 2014), conduct international continental scientific drilling program (ICDP) (Wang et al. Thus, the vertical and directional drilling are the key technologies for the exploration and exploitation of oil and gas resources, and they are also the very important ways to exploit deep geothermal energy and geo-resources (Elders et al. 2015a) the horizontal wells are usually used to develop the tight oil and gas, shale oil and gas, mainly due to the drainage area can be enlarged and it’s good for multistage fracturing, as a result, enhanced oil and gas recovery (Ma et al. ![]() For example, the extended reach wells and horizontal wells are usually used to develop the offshore oil and gas, mainly due to the required number of platforms can be reduced (Ma et al. On the other hand, to exploit unconventional petroleum resources, more and more non-vertical wells, such as directional well, highly-deviated well, extended reach well, horizontal well and etc., are utilized. On the one hand, to exploit ultra-deep petroleum resources, the vertical drilling is needed, mainly due to it can help us to reduce the down-hole accidents. 2015), coal-bed methane (Zhi and Elsworth 2016 Verma and Sirvaiya 2016) and so on, gradually be taken seriously, due to the exhaustion of conventional petroleum resources and the development of directional drilling. Therefore, more and more unconventional petroleum resources, such as shale oil and gas (Chen et al. So, according to the characteristics of well trajectory, some very important drilling methods, such as vertical drilling, directional drilling and horizontal drilling, had been developed in recent years. However, only the improvement of operational efficiency is not enough, we also need more advanced technologies to drill more complex wells, such as directional well, horizontal well, extended reach well, and multi-lateral well. In fact, the rotary drilling method was developed mainly due to the improvement of operational efficiency, and its development is very slow in recent years. According to the rock breaking method, there are two kinds of drilling methods, i.e., the percussion drilling method and the rotary drilling method, in which, the rotary drilling method is the most widely used methods (Mitchell 1995 Chen 2011 Lyons and Plisga 2016). Since 1895 the first commercial oil well was drilled using the percussion drilling method (Gatlin 1960), the drilling technologies had got a great progress. As far as we know, the only way is to drill a well. With the knowledge of crude oil and natural gas, we need to do something to get the oil and gas out from the deep formations. Finally, a brief summary and prospect of vertical and directional drilling are presented.Ĭrude oil and natural gas are usually a complex mixture of hydrocarbons, non-hydrocarbons and other trace elements, they are usually stored in the sedimentary rock of deep formations (Zou et al. The top 15+ deepest and top 20+ longest wells all over the world are collected from related literatures to analyze the achievements of vertical and directional drilling in petroleum industry, the challenges of vertical and directional drilling are also discussed. Then, the developments of the directional techniques, the main directional tools (deflection tools, down-hole motor, rotary steerable drilling system and vertical drilling system), the directional survey techniques (measuring and transmission techniques), the main drill bits (roller cone bits, fixed cutter bits and hybrid bits), and the main drilling fluids (gas-base drilling fluid, water-based drilling fluid and oil-based drilling fluid) are summarized and analyzed. It starts with the historical development and classification of main drilling methods for petroleum extraction, such as the vertical drilling, directional drilling and horizontal drilling, and the main application scopes of these methods are also discussed. The aim of the present overview is to review and discuss the vertical and directional drilling technologies and their recent developments since the pioneering work in 1890s. Meanwhile, they are also the very important ways to exploit deep geothermal energy and geo-resources, conduct international continental scientific drilling program. The vertical and directional drilling are the key technologies for the exploration and exploitation of oil and gas resources in deep formations.
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