How does a diamond bit work?

Diamond bits are an important tool for drilling. Generally, multiple bits of different sizes are used to drill an oil and gas well. When drilling the upper strata, a larger diameter bit is used because the upper strata are soft, and a single bit can be used for a shorter period of time, so a bit can be used repeatedly for several wells. The amount of drilling footage from one new drill bit depends on the size and type of the bit, the hardness and softness of the formation, and the cooperation of drilling parameters. Generally speaking, the smaller the drill bit size, the harder the formation, the less the feed; the larger the drill bit size, the softer the formation, the more the drill bit feeds. So, what is the working mechanism of the Diamond drill bit? In this article, we will take a look.

Here is the list of contents

• The advantages of diamond bits

• The rock-breaking mechanism of diamond bits

The advantages of diamond bits

To understand the working mechanism of diamond bits, first, we need to know what advantages diamond bits have in drilling work so that we can better understand the rock-breaking mechanism of diamond bits. The advantages of diamond bits are broad as follows.

First, the drill bit adopts a force balance design, which makes the bit has good guiding, adapts with downhole motor application in directional drilling, with small radial vibration.

Secondly, the reasonable arrangement of different structures of patented PDC composite pieces in different positions of the drill bit makes the bit have strong aggressiveness and anti-abrasive properties.

Third, the strong aggressive design of the diamond bit can make the bit obtain a high mechanical drilling speed.

Fourth, the dynamic flow field simulation technology is applied to the hydraulic design to optimize the flow field at the bottom of the well, which is conducive to improving chip removal speed and anti-mud pack.

The rock-breaking mechanism of diamond bits

The rock-breaking action of the diamond drill bit is done by diamond particles. To know the rock-breaking effect of the drill bit, it is necessary to understand the rock-breaking effect of single grain diamond. In the hard stratum, single grain diamond in the drilling pressure makes the rock in a very high-stress state (about 4200-5700MPa, some information that up to 6300MPa), making the rock lithological transformation, from brittle to plastic. Single grain diamond eat into the ground, under the action of torque cutting break rock, cutting depth is basically equal to the diamond particles eat into the depth. This process is like "plowing", a so-called diamond drill bit plow cutting action.

In some brittle rocks (such as sandstone, limestone, etc.), the diamond particles on the drill bit under the action of drilling pressure torque at the same time, the volume of broken rock is much larger than the diamond particles eat into and rotate the volume. When the pressure is not big, only along the diamond movement direction to form a small groove, increase the pressure will make the small groove deep and both sides of the rock broken, more than the diamond particles section size.

Diamond drill bit rock-breaking effect, in addition to the lithology and influence the lithology of external factors (such as pressure, temperature, the nature of the formation fluid, etc.), the size of the drilling pressure is an important influencing factor. It is the same as the tooth wheel drill bit, breaking rock has surface crushing, fatigue crushing, volume crushing three ways. Only when the diamond particles have enough specific pressure eat into the stratum rock, so that the rock volume crushing, in order to achieve the ideal rock breaking effect.

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