Four-Wing Concave PDC Drag Bit: High Stability · Precise Hole Quality · Strong Center Cutting
Engineered for soft to medium formations (F<8) – anchoring, grouting, water wells, and geothermal.
The four-wing concave PDC drag bit is engineered for accurate and durable drilling in soft to medium formations (F<8) and formations containing minor interlayers. Using a cross-symmetric concave blade structure combined with premium PDC cutters, the bit enhances center rock breaking and directional stability. It allows long, smooth drilling with reduced deviation and fewer bit replacements, significantly lowering total drilling cost. It is widely used in anchoring, grouting, slope stabilization, foundation engineering, gas drainage holes, water wells and shallow geothermal drilling where borehole quality and reliability are critical.
⚠️ Why Conventional Drag Bits Fail in These Formations
Contractors commonly experience: hole deviation in long holes, slow penetration due to poor center cutting, blade breakage in interbedded formations, bit balling and stuck pipe, and high replacement frequency. Soft-to-medium formations do not require harder bits — they require balanced cutting and stability.
🔧 Engineering Solution: Concave Four-Wing PDC Structure
Cross-Symmetrical Concave Blade Design
- Extremely low radial runout
- Higher hole roundness and verticality
- Reduced deviation – ideal for anchor and grouting holes
Reinforced Center Cutting Structure
The concave profile ensures center cutters contact rock first, eliminating “center core” resistance. This delivers faster penetration, smooth drilling progress, and lower torque fluctuation.
Improved Impact Resistance
Balanced load distribution across four blades adapts to thin interlayers, reduces blade breakage, and ensures stable drilling in complex formations – with longer service life than standard drag bits.
Efficient Cuttings Removal
Concave cavity + large junk slots + optimized hydraulics enable rapid debris evacuation, reduced bit balling, lower sticking risk, and continuous drilling operation.
Extended Wear Life
Premium PDC cutters with uniform layout ensure even wear distribution, lower single blade load, longer footage per bit, and lower cost per meter.
✅ Key Advantages
📍 Typical Applications
⛰️ Suitable Formations
Soft to medium formations (F<8): Sandstone, mudstone, coal seam, shale, limestone, marble. Suitable for formations with minor interlayers. Not recommended for granite, basalt or highly abrasive formations.
💧 Recommended Drilling Method
Rotary drilling with mud circulation or clean water circulation. Proper circulation improves cooling, cleaning and service life.
📏 Available Sizes (mm)
75 / 91 / 113 / 133 / 153 / 171 / 200 / 220 / 245 / 275 / 300 / 325
Custom diameters and concave depth available.
🔩 Connection Types
⚙️ Custom Engineering Service
We provide full customization based on drilling conditions:
- Cutter density optimization
- Concave depth adjustment
- Blade geometry modification
- Custom thread connection
- Formation-specific design
📋 Field Case: Slope Stabilization Project
A highway slope stabilization project in Sichuan required 20-meter anchor holes in interbedded sandstone and mudstone. Conventional drag bits deviated beyond tolerance and broke blades in thin hard layers.
A 115mm four-wing concave PDC bit with reinforced center cutting and optimized hydraulics was deployed.
- Hole deviation <0.5°
- ROP increased 2.1×
- One bit completed 18 holes
- No blade damage
🚀 Conclusion
The four-wing concave PDC drag bit offers a balanced combination of stability, durability and penetration efficiency. For projects requiring accurate boreholes and reliable performance in soft to medium formations, it provides a cost-effective alternative to conventional drag bits. Whether for anchoring, water wells, or geothermal drilling, this engineered solution delivers measurable improvements in hole quality and drilling economics.