Four wing scraper bit and three wing scraper bit are customized by the manufacture

  Scraper bit is a kind of cutting bit with fins commonly used in oil drilling in the upper soft formation
It can be divided into two wings, three wings and four wings
The commonly used three wing scraper bit is
There are two kinds of wing shapes: stepped shape and non stepped shape, and its edge is inlaid with cemented carbide or diamond
According to the needs, scraper bit can be divided into coring and non coring
Our company has been engaged in oil fields, mines, geological survey, hydrological exploration, engineering piling, geothermal development, water wells and other applications (Jianghan bit, Lilin bit, Feilong bit, Shanghai bit, CHUANSHI bit) three cone and single cone inlaid bit and steel tooth bit
At the same time, we will provide specific solutions according to customer requirements and actual drilling conditions, Customized assembled bits with any diameter, including large-diameter machine pile bits, different types of bits, reaming bits, directional well bits, etc
The bits commonly used in the construction of water well drilling rig include scraper bit, cone bit, diamond bit, cemented carbide bit, PDC bit and special bit
This paper focuses on explaining the relevant knowledge of scraper bit for friends
Scraper (vane) bits are divided into two blade bits, three blade bits and four blade bits according to the number of scraper blades
1
Structure of scraper bit The structure of scraper bit can be divided into four parts: upper bit body, lower bit body, blade and nozzle
1) Upper drill bit body the upper drill bit body is located at the upper part of the drill bit, is equipped with threads to connect the drill string, and the side is planed with a groove for installing welding pieces, which is generally made of alloy steel
2) Lower bit body the lower bit body is located at the lower part of the upper bit body and welded with the upper bit body
Three water holes are opened inside to install the nozzle
It is generally made of alloy steel 3) Blade blade blade is the working edge of the scraper bit that directly contacts and breaks the rock, also known as the scraper blade
Generally, the scraper bit is named after its number of blades
For example, three blades are called three scraper bits, and two blades are called two scraper bits or fishtail scraper bits
The blade is welded on the bit body
Generally, the three scraper bit is commonly used 2
Working principle of scraper bit The scraper bit mainly breaks the formation by cutting, shearing and extrusion
These rock breaking methods are mainly to overcome the shear strength of the rock, which is easier than overcoming the compressive strength of the rock
Rock breaking is generally divided into the following three processes: (1) after the rock in front of the edge is broken along the shear plane, the torsional moment decreases, the cutting edge is pushed forward and collides with the rock in front of the edge
(2) Under the action of torsional moment, the rock in front is crushed to produce small shear fracture, and the torsional moment increases
(3) The blade continues to squeeze the rock in front (partially crushed into powder)
When the torsional moment increases to the limit value, the rock breaks along the shear plane, and then the torsional moment suddenly decreases; The three processes of collision, crushing, small shear and large shear are repeated to form the whole process of broken plastic brittle rock 3
Reasonable use of scraper bit for water well drilling rig 1) The scraper bit is suitable for drilling in various soft to soft soil layers and plastic and plastic brittle formations such as mudstone, argillaceous sandstone and shale
2) Precautions for using scraper bit in water well drilling rig (1) precautions before going down the well: ① do not collide violently when moving and placing the bit to prevent damage to cemented carbide, artificial diamond polycrystalline and bit thread shoulder
② The scraper bit is selected for the water well drilling rig, and its outer diameter, height and nozzle size shall be measured to see if they meet the design requirements, and records shall be made
(2) Precautions for operation: ① when connecting the drill bit, the screw thread must be tightened with internal and external pliers, not with a single Tong, so as to prevent breaking the scraper blade and damaging the cemented carbide
② When a new scraper bit is used for the well drilling rig to go down the well, it is necessary to drill 0
5m with light WOB at the beginning, drill a new bottom suitable for the shape of the bottom edge of the new bit, and then add it to the specified WOB for drilling
③ Each time a single running tool is connected, start the rotary table before the bit contacts the bottom of the well, and then put it down to the bottom of the well for pressurized drilling
It is forbidden to start the rotary table under pressure to prevent breaking the scraper blade
④ In case of soft and hard formation interface, in order to prevent well deviation and poor drilling, a small WOB drilling shall be adopted, and then pressurized to the specified WOB drilling after passing through the interface
⑤ It is required to feed the drill evenly, and it is strictly prohibited to release and press the drill hard to prevent the scraping blade from being broken and the well deviation
(3) Determination of tripping out time: the tripping out time of scraper bit is determined from the following two aspects: first, the mechanical ROP decreases significantly, the drilling skip phenomenon, and the home weight or pump pressure increases suddenly; When the outer diameter of the reamer is not the same as that of the drill bit, especially when the outer diameter of the reamer is not the same as that of the drill bit