Polycrystalline Diamond Compact bit, known as PDC drill bits, is made up of small cutting blocks which consist of polycrystalline diamond thin round sheet inserted onto the drill bit body. It is suitable for soft to medium-hard formations.
PDC bit is an integral drill which hasn’t activity components. The structure of PDC bit is very simple, it generally includes drill body, cutting teeth, nozzle and junk slot, etc.
Detailed description
PDC bit can be divided into two types: steel body and tungsten carbide matrix. The surface of steel body PDC bit is easily to be eroded. While tungsten carbide matrix PDC bit is difficult to eroded.
Selfsharpening of PDC tooth is very good. Polycrystalline diamond grains shed in the process of cutting the rock and form new blade grain to update the selfsharpening. In addition, tungsten carbide substrate forming sharp cutting edge after wearing, exhibiting good antiimpact performance and providing flexibility for diamond.
Operating principle:
1. Crushing process of soft plastic formations:
Continuous cutting, similar to the process of machine tools cutting the metal.
2. Crushing process of hard brittle formations:
Crash--- crushing and small shear---big shear
Size and formations:
Diameter(in)
|
Applicable formations
|
24
|
Dead-soft
|
19
|
soft
|
16
|
medium
|
13
|
Medium-hard
|
8
|
hard
|
Drilling and Completion Fluids
carrying cuttings out of the hole; cleaning, cooling and lubricating the diamond bits; giving buoyancy to the drill string; controlling formation fluid pressures; preventing formation damage; and providing borehole support and chemical stabilization. There are three types of drilling fluids: water-based, oil-based and synthetic-based. Technical requirements, cost, availability, and environmental concerns can all influence the selection of fluid type. However, as wells penetrate deeper formations, extreme conditions can result in failure of the drilling fluid to perform as needed.
For example, the role of the drilling fluid to act as a lubricant to reduce torque and drag on the drill pipe and bit becomes increasingly important in deep drilling. High temperatures encountered at greater depths can cause a direct change in the lubricating capacity of drilling muds. At the same time, the better lubricating qualities of oil-based and synthetic-based drilling fluids may become less available to drillers due to environmental regulations restricting their use. The development of new lubricating materials (e.g., solid beads) is currently being investigated as an effective means of reducing friction.
Also, with deeper wells the weight of the total amount of fluid moving through the drilling system can become a concern. New technology that can reduce the weight of drilling muds without compromising other characteristics will increase the efficiency of drilling operations. In particular, developing drilling fluids that can control subsurface pressures and maintain the stability of the wellbore without harming the permeability of productive formations is an important area for research.
Finally, although oil-based muds can perform better at greater depths, disposing of the used mud and the oil-soaked cuttings can be a challenge. Developing affordable synthetic-based drilling fluids that provide the performance characteristics of oil-based muds without the environmental drawbacks, and developing new techniques for treating or reclaiming mud and cuttings, are additional areas for research.
For example, the role of the drilling fluid to act as a lubricant to reduce torque and drag on the drill pipe and bit becomes increasingly important in deep drilling. High temperatures encountered at greater depths can cause a direct change in the lubricating capacity of drilling muds. At the same time, the better lubricating qualities of oil-based and synthetic-based drilling fluids may become less available to drillers due to environmental regulations restricting their use. The development of new lubricating materials (e.g., solid beads) is currently being investigated as an effective means of reducing friction.
Also, with deeper wells the weight of the total amount of fluid moving through the drilling system can become a concern. New technology that can reduce the weight of drilling muds without compromising other characteristics will increase the efficiency of drilling operations. In particular, developing drilling fluids that can control subsurface pressures and maintain the stability of the wellbore without harming the permeability of productive formations is an important area for research.
Finally, although oil-based muds can perform better at greater depths, disposing of the used mud and the oil-soaked cuttings can be a challenge. Developing affordable synthetic-based drilling fluids that provide the performance characteristics of oil-based muds without the environmental drawbacks, and developing new techniques for treating or reclaiming mud and cuttings, are additional areas for research.
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