A special drill bit and method for active piercing drilling of jack-up drilling platform legs

Abstract

The invention relates to a special drill bit of active piercing drilling of pile legs of a self-elevating drilling platform and a method. The special drill bit comprises a drill bit main body with the top being provided with a male buckle connector and branched roller bits with the bottoms provided with water holes. The drill bit main body can be connected with the bottom of a drill stem of a drilling machine through the male buckle connector. The bottom of the drill bit main body is fixedly provided with a plurality of mandrels of a pipe column structure in a multi-point distribution mode. The branched roller bits are separately mounted on all the mandrels and can rotate around the mandrels. The drill bit main body is further internally provided with an internal flow channel. The mandrels are internally provided with central hole channels. The central hole channels of the mandrels communicate with the internal flow channel of the drill bit main body. The water holes of the branched roller bits communicate with the central hole channels of the mandrels. By adoption of the special drill bit, active piercing operation that an egg shell stratum is efficiently destroyed in a large area mode through one time of drilling can be achieved, drill stem tripping operation can be greatly reduced, operation cost of active breaking of the egg shell stratum is reduced, and operation safety is effectively ensured.

Description

technical field [0001] The invention relates to a special drill bit and a method for drilling holes and breaking ground, in particular to a special drill bit and a method for actively piercing through the pile legs of a self-elevating drilling platform. Background technique [0002] The jack-up drilling platform is one of the important equipment for offshore drilling and completion, and has become the main force of drilling and completion equipment in waters less than 120 meters deep. The jack-up drilling platform relies on the legs standing on the seabed to support the hull, drilling rig and other equipment, and the hull and operating equipment climb to a certain altitude to carry out drilling and completion operations. However, the pile legs standing in the shallow soil layer of the seabed bear the hull, equipment and operating loads, which will inevitably destroy the shallow soil layer of the seabed and cause instability. The phenomenon that the legs of the jack-up drill...

AI Technical Summary

Problems solved by technology

In order to actively drill holes to break the huge "egg shell" formation, it is necessary to drill dozens or even hundreds of holes in the formation, resulting in dozens or even hundreds of trips of the drill string to complete active piercing with conventional drill bits Drilling operations have extremely low operating efficiency and high operating costs. For offshore drilling operations with high daily costs, the active piercing method of conventional drill bit drilling is not economical

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