The life of a diamond bit is generally defined as the total amount of footage the bit can drill from the time it starts working to the time it cannot drill. In the process of drilling, the bit may encounter two kinds of normal wear and abnormal wear, and the abnormal wear will affect the life of the bit. As the design, manufacture and use of diamond-impregnated drill bit is a very complex system engineering, the life of the drill bit has a complex relationship with diamond parameters, the performance of the matrix composition, the drilling process and the properties of the rock drilled and other factors. Only by coordinating with each other, can the potential of the drill bit be fully tapped and the life and efficiency of the drill bit be improved. Therefore, the diamond bit from the design, mold, material selection, firing, each link has a great impact on its life, these links affect the service life of the bit, affect the efficiency of drilling construction.
According to the process of designing, manufacturing and using diamond-impregnated bit, the life of diamond bit is affected by four factors: the nature of the rock drilled, the quality of the bit itself, drilling process parameters and construction process management.
1. Properties of the rock drilled
In the process of drilling into broken rock, the diamond bit itself is worn down by the rock and gradually becomes dull until it is damaged. In diamond-impregnated drilling, necessary abrasive wear is very important to help the diamond bit self-sharpen, so that the bit can work properly, improve the efficiency of rock crushing, and increase the life of the bit.
The ability of the rock being drilled to wear the diamond bit is called abrasiveness. The main factors that affect the abrasive property of rock are the hardness and abrasive property of rock particles, the shape, size, porosity, the mineral type and type of rock, the bond strength of rock, rock medium and so on. The abrasive property of rock determines the efficiency and life of rock crushing tool, and has great influence on the parameter selection of drilling process and the design and use of drill bit.
2. Performance of diamond bit
The life of a bit is not only affected by the rock affected, but more importantly depends on the properties of the bit, structure and other performance parameters, because the properties and composition of the rock are uncontrollable factors, and the quality of the bit itself can be improved through reasonable design and advanced manufacturing process. For the diamond bit itself, the wear resistance of the bit plays a decisive role among the factors affecting its service life (in some conditions, the wear resistance of the matrix is consistent with the hardness and erosion resistance of the matrix. For example, under the same matrix formula, the higher the hardness, the higher the wear resistance and erosion resistance of the matrix). The wear resistance of the bit includes the wear resistance of the diamond on the lip and the wear of the matrix material. In diamond-impregnated bits, these two aspects need to work together to achieve good results, that is, the wear of the diamond is slightly slower than the wear of the body, which can ensure the continuous cutting of the diamond during drilling, maintain the efficiency of the bit, and improve the efficiency of drilling and construction. On the contrary, it will cause the drill to fail without cutting edge.
3. Drilling process parameters
Drilling process parameters such as weight on bit, rotational speed and pump volume also have a great impact on the life of the bit. The three are not independent, but need to cooperate with each other to achieve good drilling effect. For example, if weight on bit is too high, the amount of cuttings increases, and the diamond completely penetrates into the rock formation, and the conditions of cooling and powder discharge at the bottom of the hole deteriorate. Bit wear increases, leading to reduced bit life, and pumping can be increased to speed up powder discharge and bottom cooling to protect the bit. In the production process, we need to choose reasonable parameters to improve efficiency. In the process of drilling, the drill bit has been doing irregular movements in the hole, such as jumping up and down, swinging from side to side, and swirling at the bottom of the hole. As diamond is a brittle material with low impact resistance, it is easy to suffer impact damage in the irregular vibration of drilling, which will greatly affect the life of the drill bit.
4. Drilling construction management
After the diamond bit is successfully manufactured, it is used in the drilling production site and after proper drilling parameters are selected. If the drill bit is not well suited to the formation, it may not be drilled, drill inefficiently, or wear out too quickly. This will affect the quality of the drilling process, and the degree to which the drill is performed during drilling will affect the life of the bit.
