Wireline Core Barrels

The wireline core barrels is a special drilling tool that allows obtaining the core without lifting the full drilling tool during geotechnical drilling construction. This technique achieves efficient core retrieval by using a special salvage device with a wire rope to lift the inner tube containing the core from the bottom of the hole to the surface through the center hole of the hole's drill pipe. The features of the rope coring technique include high drilling speed, long diamond bit life, and high time utilization while reducing the labor intensity of workers. In addition, this technique improves drilling efficiency by reducing the number of lifts and down drills and the auxiliary time for lifting and lowering drilling tools, which in turn improves the average work efficiency. The structure of rope coring drilling tools mainly consists of two major parts, namely, single-acting double pipe and salvage device, in which the double pipe part includes outer pipe assembly and inner pipe assembly, while the inner pipe assembly includes spearhead, bullet card, single-acting assembly, alarm, adjusting assembly, inner pipe, suspension support and core chucking assembly, and so on. This technology not only has good geological effect, but also has high productivity and low drilling cost, which is a very effective technical means in geotechnical drilling construction.

The working principle of wireline corer mainly involves the use of components such as inner and outer core pipe assemblies, inner core salvage devices, and specialized drilling bits to lift the inner core pipe containing the core from the drill pipe from the bottom of the hole to the surface by means of a winch and wireline. This technology allows the core to be removed from the bottom of the hole without lifting the full set of drilling tools, which reduces the drilling assistance time, increases the pure drilling time, improves the drilling efficiency and project quality, and also reduces the labor intensity and cost. The cable corer is a device for coring from the bottom of the well without lifting the drilling tools. It consists of inner and outer core pipe assemblies, inner core pipe salvage device and other components. When using the cable corer for coring, the inner and outer core tubes are locked with a spring-loaded bayonet. It is also possible to stop pump drilling after drilling a certain footage, grab the salvage head of the inner core pipe by lowering the salvage device to reach the bottom of the hole, and then lift upward to disengage the bayonet, separating the inner core pipe from the outer core pipe, and lift the inner core pipe from the drilling rod to the ground to take out the rock core. After coring, the inner core tube is reinserted from the drill pipe and the outer core tube is clamped again when it reaches the bottom of the hole. The flushing and drilling is then turned on and the coring and drilling continues.
Rope core drilling rigs are designed with different formation conditions in mind, including rope core drilling rigs for drilling straight wells, drilling horizontal wells, and drilling dry wells, as well as rope core drilling rigs for drilling intact formations and for drilling loose and fractured formations. In loose and fractured formations, these drills typically have a clearance of 3 - 5 mm, while in hard rock, a lifting force of 2 - 3 tons is required to break and grip the core. The outer pipe and drill column can be moved upward until the inner pipe is stuck in the inner wall of the drill step and cannot be moved. At this point, the inner pipe assembly can be smoothly raised out of the borehole. When the inner tube is full of core, the captain sometimes needs to use a three-tube core bucket to collect soft core samples. Rope coring rigs are also designed to include in-place indicators to ensure that the inner tube assembly is in place and the suspension ring is adhered to the outer tube seat ring for a smooth coring process.

• Handle with care to avoid damage to the coring tube and its components.
• Install the threaded bushing to ensure a tight connection.
• Prevent threads from being damaged and avoid damage during operation.
• Carefully inspect the inner and outer tubes to ensure they are in good condition and suitable for use.
• Wear gloves when operating to protect your hands and minimize damage to the pipe from direct contact.
• When drilling with a rope coring tool, increase the drilling pressure and reduce the flow rate of flushing fluid accordingly.
• If there is a sudden increase in pump pressure during drilling, this may mean that the core is clogged. In this case, drilling should be stopped immediately and salvage should be performed.
• As soon as the inner pipe assembly is raised, it should be removed from the salvage unit and checked for core collection. If core collection is normal, the spare second inner tube assembly can be put into service.
• When using the rope coring tool, especially in lost-well formations or when there is no mud in the well, special attention should be paid to the method of operation to avoid damage to the inner tube assembly.