شرح للدقاقات من نوع بي دي سي-PDC Drill Bits

شرح للدقاقات من نوع بي دي سي-PDC Drill Bits

PDC Drill bits have been used considerably and successfully over colorful conformation types. The lack of rotating corridor leads to lesser life expectation, as long bit runs are attainable with attendant time and cost savings( check also drilling cost per bottom). Due to its increased cost, drilling masterminds shall completely review the economics of running a PDC drill bit before bit selection.




PDC bits have several significant design features that enhance their capability to drill

1. The lack of internal moving corridor reduces bit failure eventuality.
2. Since it fails the gemstone by shearing, it'll bear lower drilling trouble than the cracking and grinding principles used in comber cone bits.
3. No demand for high- bit weights.( more applicable in divagation control.)
4. The low- weight conditions and no internal moving corridor make them well- suited for turbine drilling.

Bit manufacturers integrate the PDC blank into their separate bit designs(Fig. 1). Variations in designs include the number and placement of the blanks, spurt structure, and watercourse development. In some operations, PDC bits will drill 3- 4 times the footage of a conventional comber bit at 2- 3 times the drilling rate if sticky conformations don't pose problems. For illustration, 18,000- 20,000 ft wells in South Texas generally complete in 70- 80 days using PDC bitsvs. 120- 130 days with conventional comber bits.




The manufacturing of PDC bits is either with a crafted sword or a matrix body process. The matrix process is analogous to the manufacturing of diamond bits. The knives are attached to the bit by personal ways. Matrix bodies appear to be further corrosion- resistant.

The shape of the PDC knives is getting an important consideration. utmost manufacturers use the original indirect design. still, there are numerous exploration and development sweats to enhance the design and ameliorate drilling performance.

The Major operations OF PDC Drilling Bits

1. PDC bits are generally helpful for drilling long, soft, to medium shale sequences with low abrasivity. similar conformations generally parade high ROP and extended life, allowing entire drilling sections on one run.
2. PDC bits aren't generally applicable for a largely abrasive well or cemented beach sequences. Drilling tight siliceous conformations may lead to PDC dicing and breaking. In addition, it may affect in lower than anticipated ROP and bit life.
3. Drilling miscellaneous conformations containing interspersing shales and/ or shale limestone sequences encourage the operation of mongrel PDC bits. This bit incorporates the use of backup diamond superstuds behind the PDC knife.
4. When drilling harder abrasive strings, the diamond superstud absorbs the increased weight needed to drill the stringer, precluding unseasonable damage and wear to the PDC knife.
5. Drilling hard conformations may bear the use of bladed mongrel PDC bits. The deep watercourse on these bits enables optimum fluid inflow across the knife to reduce the disunion temperatures convinced efficiently. This effective cooling will help minimize the fracture of the PDC knives.
6. It's a good practice to consider eccentric PDC bits when drilling mobile plastic conformations similar as swab sections. These bits have successfully averted wedged pipes in areas with swab inflow problems.
7. Drilling masterminds may consider long phased profile bits when planning for slush motors or turbines. In addition, radial jetting bits reduce the eventuality for disunion- convinced high knife temperatures when run on a motor or turbine, reducing the knife’s temperature declination.

PDC Drill Bit Design & Components

What are The Main Steps Of PDC Bit Design are

1. Bit Body Material Design
2. PDC knives Material
3. PDC knife figure
4. knife Shape
5. Bit Profile figure
6. PDC Drill Bit Body

The bit body design may be

sword Body The bit body is forged or mulled from sword( sword- bodied bits). The knives on a sword body bit are manufactured as superstuds. The superstud can be set with a fixed back rake and/ or side rake( will be bandied latterly). Field experience with the sword body bit indicates that face corrosion is a problem, but numerous overcome this by applying a hard- facing emulsion to some extent. Steel body bits also tend to suffer from broken knives due to limited impact resistance. This limited impact resistance is because there's no support to the superstud knife. numerous prefer tham as they can be fluently repaired but suffer from corrosion.

Matrix Body PDC Matrix Body drill Bits are constructed in a cast from tungsten carbide( matrix bit). They're more resistant to corrosion but are prone to bit balling in soft complexion conformations due to their low blade height compared with sword- bodied bits. Matrix body bits have an profitable disadvantage because the raw accoutrements used in their manufacture are more precious.



Fortunately, sword and matrix PDC drill bits fleetly evolve, and their limitations are dwindling. As hard- facing accoutrements ameliorate, sword bits are getting significantly well- defended with accoutrements that are largely resistant to bruise and corrosion. At the same time, matrix accoutrements ’ structural and wear- defying parcels are also fleetly perfecting, and the range of profitable operations suitable for both types is growing.

moment’s PDC drill Bits Design as a matrix has little resemblance to that of indeed a many times agone

. Tensile strengths and impact resistance have increased by at least 33, and knife brazes strength has increased by ≈ 80. At the same time, shapes and the technology of supporting structures have bettered, performing in robust and productive matrix products.

cutter Material

PDC knives are made from carbide substrate and diamond fortitude. The high heat of around 2800 degrees and high pressure of roughly psi forms the compact. A cobalt amalgamation also acts as a catalyst for the sintering process. The cobalt helps bond the carbide and diamond.

Number of cutter

We generally use smaller knives on soft PDC bits as each knife removes a lesser depth of cut. For harder conformations, it's essential to use further knives to compensate for the lower depth of cut.

PDC Drill Bits – Cutters Size

For softer conformations, we generally choose larger knives than in harder conformations. generally, the standard range of sizes is from 8 mm to 19 mm on anyone bit.

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We generally describe the knife rack design exposure by back rake and side rake angles.

• The cutter back rake is the angle presented by the face of the knife to the conformation and is measured from the perpendicular. Back troll angles vary between, generally, 15 ° to 45 °. They aren't constant across the bit, nor from bit to bit. The magnitude of the knife rake angle for PDC drill bits affects Penetration Rate( ROP) and knife resistance to wear. As the rake angle increase, ROP diminishments, but the resistance to wear increases as the applied cargo is now spread over a much larger area. PDC knives with small back rakes take large depths of cut and are thus more aggressive, induce high Torque, and are subject to accelerated wear and tear and lesser threat of impact damage.

The cutter side rake is an original measure of the exposure of the knife from left to right. Side rake angles are generally small. The side rake angle assists hole cleaning by mechanically directing slices toward the annulus.

cutter Shape

The most common PDC Drill Bits shape is the cylinder, incompletely because it's easier to arrange spherical knives within the constraint of a given bit profile to achieve large knife consistence. Electron line discharge machines can precisely cut and shape PDC diamond tables(Fig. 8). Nonplanar interface between the diamond table and substrate reduces residual stresses. These features ameliorate resistance to dicing, spalling, and diamond table delamination. Other interface designs maximize impact resistance by minimizing residual stress situations.


Specific knife designs incorporate further than one diamond table. The interface for the primary diamond table is finagled to reduce stress. A secondary diamond table is located in the high- bruise area on the ground- engaging side of the knife. This two- league arrangement protects the substrate from bruise without compromising the structural capability to support the diamond table.

largely specialized knives are designed to increase penetration in tough accoutrements similar as carbonate conformations. Others include finagled relief in the tungsten carbide substrate that increases Penetration Rate( ROP) and reduces the demand for Weight On Bit( WOB) and Necklace or scratched diamond tables that reduce effective knife back rake and lower bit aggressiveness for specific operations.

cutter Exposure

The knife exposure is the quantum the knives bag from the bit body. It's essential to insure that the exposure is high enough to allow good cleaning of the bit face but not so high as to reduce the mechanical strength of the knife.

High exposure of the knife provides further space between the bit body and the conformation face, while low exposure provides good backup and support to the knives.

Number of PDC Drill Bit Blades

Using the same analogy for comber cone bits, a PDC bit designed for soft jewels has smaller blades( and knives) than one designed for hard jewels.

• The soft conformation PDC bit will have a large junk niche area to remove the large volume of cut gemstone and reduce bit balling in complexion conformations.
• A hard conformation PDC bit with numerous blades requires numerous small knives, as each knife will remove a small quantum of gemstone.

Blade Height

A soft conformation PDC bit will have a larger blade height in its design than a hard PDC bit, with a consequent increase in the junk niche area. Advanced blades can be made in sword- bodied- bits than matrix bits because of the lesser strength of sword over that of the matrix.

Blade figure Design

Bit blades range from straight to complex wind shapes. Experience has shown that twisted blades give excellent stability to the bit, especially when the bit first connections the gemstone.

PDC Drill Bit Profile Design

Bit profile affects both the cleaning and stability of the PDC bit. The two most extensively used biographies are

A – Double cone The double cone profile allows placing further knives near the hand giving better hand protection and allowing better directional control.

B-shallow cone The shallow cone profile gives a briskly Penetration Rate( ROP) but has lower area for cleaning.
Generally, a bit with a deep cone will tend to be more stable than a shallow cone.

Bit Length

The bit length selection is important for steerability. Shorter bits are more steerable. The two bits on the left below Figure are deviate bits( also check deviate drilling) with a short, flat profile.

The ‘ Steering Wheel ’ bit on the right is designed for general directional work.





As bandied, the most significant quantum of work is done on the heel and hand of the drilling bit. PDC drill bits that wear more on the hand area will leave an Under hand Hole, which will bear reaming from the coming bit. Reaming is time- consuming and expensive and, in some cases, can destroy an entire bit without drilling a single bottom.

Hence maintaining a hand is veritably important. We can place one or further PDC knives in the hand area. Pre-flatted knives are used to place further diamond tables against the hand. Tungsten carbide inserts, some with natural or synthetic diamonds bedded in them, may be placed on the hand of bit 1.

A significant advantage of fixed knife bits over comber cone bits is that there may be an extension for the hand on fixed knife bits to a further considerable length of the drill bit.

Conclusion

When we put all of the below PDC Bit Design features together, you'll find

• PDC drill bit designs depend on high or low RPM operations, i.e., turbinevs. rotary drilling. Turbine operations use further blanks to compensate for disunion- related wear and tear considerations. The tapering of the PDC bit allows the placement of the knives. PDC bits for rotary operations have smaller knives and a flat design.
• Rotary- designed PDC bits frequently use snoots to allow fluid rotation for slices junking and cooling of the bit. Manufacturers may vary the number and distribution of the snoots. A tendency for operations in Water- Grounded slush is to use small spurts to achieve high fluid rapidity. This point isn't as significant in oil painting Grounded slush operations.
• The PDC bit on the extreme left wing of the below Figure is a light set bit with a many high blades and a many large knives with small reverse rake angles. therefore light set bits generally have a many high blades, with many large knives, presumably with a low reverse.

For hard jewels, PDC bits will have further blades, with lower and further multitudinous knives, and this trend continues to the heavy set bits on the extreme right of the below Figure.

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