PHD-IUW Variable Wall Internal Upset Wireline Core Drill Rod

PHD-IUW is a special variable-wall internal upset reinforced wireline core barrel rod for ultra-deep holes, fully compliant with DCDMA international drilling standards. The base tube blank features dimensions of Φ114.3 × 5 mm and is manufactured via exclusive integrated internal upset forging. The upset section has an inner diameter of 101 mm and an outer diameter of 115 mm. The blank is made of ZT950 high-strength alloy steel dedicated to deep drilling, combined with composite heat treatment: hot upset thickening at rod ends plus medium-frequency zoned quenching and tempering over extended sections at both ends. Its maximum recommended safe drilling depth reaches 2,850 m. It is applicable to ultra-deep mineral resource exploration, geothermal deep well investigation, deep geological scientific coring, and ultra-deep borehole construction for large geotechnical engineering projects.

Compared with conventional equal-wall standard PHD (PQ) core rods, this product adopts a differentiated variable-wall internal upset structural design that significantly enlarges the cross-sectional bearing area of joints. It delivers comprehensive upgrades in five key aspects: tube purity, joint torsional and tensile bearing capacity, fatigue resistance under alternating loads, thread wear and corrosion resistance, and lightweight tube design with large internal flow passage. Balancing ultra-high structural strength and excellent tube toughness, it fits ultra-deep straight holes and high-inclination deviated holes ranging from 2,500 m to 2,850 m, as well as dense hard rock formations, fractured structural zones, and complex aquifers with high mineralization. It effectively prevents frequent failures under ultra-long drill string working conditions, including joint tearing, thread tooth collapse and slippage, tube bending and deformation, and fatigue fracture at heat treatment transition zones. It is universally compatible with all standard PHD (PQ) wireline core accessories, including inner tube assemblies, overshots, diamond core bits and reaming shells. New and existing PHD (PQ) core rods of the same standard can be mixed and matched on site.

1. Composite Reinforcement via Variable-Wall Internal Upset & Zoned Quenching-Tempering, Adapted for 2,850 m Ultra-Long Drill String Conditions

Limited by equal-wall structures, conventional standard PHD (PQ) core rods generally have a maximum construction depth below 2,400 m. The PHD-IUW features custom internal upset variable-wall joints paired with extended-section double-end quenching & tempering heat treatment, greatly expanding the bearing cross-section of joints. It stably bears the dead weight of 2,850 m ultra-long drill strings and high-torque rotary loads from deep formations, drastically improving overall fatigue and impact resistance of joints and threads, and sharply cutting construction accidents such as deep-hole rod breakage, joint tearing and thread disengagement.

2. Lightweight 114.3×5 mm Tube with Large Internal Flow Passage for Higher Drilling Efficiency

Optimized thin-wall design with 5 mm wall thickness on the base tube effectively reduces the dead weight of the entire drill string and lowers tripping resistance during round trips at 2,850 m deep wells. The tube boasts a large internal flow passage of 104.3 mm ID, enabling sufficient circulation flow of flushing fluid, faster removal of cuttings at deep hole bottoms, continuous cooling of diamond bits, and improved comprehensive continuous coring efficiency in ultra-deep boreholes.

3. Integrated Internal Upset Forming Eliminates Hidden Dangers of Stress Fracture Caused by Wall Thickness Mutation

Manufactured via integrated closed-die hot forging internal upset forming, it simultaneously achieves thickened and widened joints with 101 mm inner diameter and 115 mm outer diameter, alleviating stress concentration induced by wall thickness discrepancy between tube bodies and joints of ordinary core rods. The uniform metallographic structure of heat treatment transition layers enables long-term resistance to high-pressure extrusion, high-frequency rotary vibration and hard rock impact loads in deep wells, solving the industry-wide pain point of fatigue fracture at transition sections of ultra-long drill strings.

4. Universal PHD (PQ) Standard Threads – No Replacement of Existing Matching Drilling Tools, Saving Project Costs

Taper pipe threads are machined strictly in accordance with DCDMA international PHD (PQ) standards, with fully matching taper, pitch and tooth profile dimensions compatible with mainstream full-set PHD (PQ) wireline core accessories available on the market. Existing in-service inner tube assemblies, overshots, reaming shells and diamond bits can be directly matched. Mixed construction of new and old core rods eliminates the need for full replacement of drilling consumables, cutting equipment procurement and operation & maintenance costs.

5. Composite Hardening & Protection for Threads for Long-Term Underground Corrosion Resistance and Anti-Galling Performance

After precision finishing, threads undergo dual anti-rust hardening treatment of nitriding plus phosphating. They resist corrosion and seizure even after prolonged immersion in highly mineralized groundwater and acidic drilling mud. Smooth breakout is still achievable after long-term shutdown and static placement, reducing downtime losses caused by thread locking and stuck pipes in ultra-deep holes.