Recent years, as blooming of many projects and construction works in China, overburden casing drilling systems have got a very big development due to the very large marketing demand. At the same times, the technics also get very good evolvement. During the past ten years, Acedrills Rock Tools have built a very complicate overburden and casing drilling products system for such kind of drilling needs, which includes but is not limited to the three typically ones in this chapter.
In practice, the eccentric overburden drilling systems (ODEX / Stratex / Tubex / ODS) of three components (mentioned to the guide device, eccentric reamer and pilot bit), symmetric casing drilling systems of two components (ring bit and central pilot bit) and double head casing drilling systems (double drill strings) are the most widely used ones, among them the double head casing drilling systems are mainly used for anchoring. Nowadays, these technologies are very mature and reliable.
Others like Eccentric Overburden Drilling Systems of two components (guide device and eccentric pilot bit) or five components (the reamer bits consist of three parts rather than one) are also available. Some special ones (like the ones that with two symmetric reamer parts) are also under developing, which are planned to be put to the market in the coming year.