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Coring Tools and Core Barrels Conventional coring tools, oriented coring tools, horizontal coring tools, directional coring tools and other coring tools for oil and gas drilling are available. Their average core recoveries are over 95% and maximum well depth exceed 8400 meters. Conventional Coring Tools Conventional coring tools are similar to DBS coring tools but not interchangeable. The outer barrels are made of thick-wall seamless steel tubes, and equipped with multiple stabilizers, which make it high strength, high rigidity, and help to improve core recovery as well as elongate work life of diamond coring bits. In addition to steel inner barrel, others made of fiberglass, aluminum alloy and stainless steel are also available, which are light, temperature-resistant, abrasion-resistant, high strength and smooth inner wall. Small resisting force when core entering inner barrel is advantageous for improving core recovery when coring in unconsolidated or broken formation. More than 5 models of core catchers are designed for different formations. Complete auxiliary tools make it more simple to core and more time to be saved, especially when used in costly areas such as offshore operation. Chuan-5 coring tool is the upgraded product of Chuan-4, whose swivel assembly has been equipped with automatic relieving installation, which allows bypass valve and check valve installed on drilling assembly when coring in high pressure hydrocarbon reservoir. Meanwhile it can prevent mandrel from damage by high density drilling fluid, and improve the rotary ability of inner barrel. Horizontal Coring Tools When coring in horizontal well, radial alignment bearing is specially designed for swivel assembly and bit throat in order to prevent inner barrel from rotating, and ensure only one of the two barrels rotating. The waist-drum-like straight-rib stabilizer, making for maintaining angle, will not only reduce dragging to borehole wall but also friction drag during tripping operation to the maximum. Its maximum curvature is 48° /100m.
