The HT and HD heavy-duty core barrels were developed for high torque, long footage coring in highly deviated holes. They cut 2-1/8’ and 5-1/8’ diameter cores, respectively. Solidly constructed of high structural alloy steel tubing, the core barrels feature a safety tool joint upset.
HT and HD Series oil Core Barrels
The HT and HD heavy-duty core barrels were developed for high torque, long footage coring in highly deviated holes. They cut 2-1/8’ and 5-1/8’ diameter cores, respectively. Solidly constructed of high structural alloy steel tubing, the core barrels feature a safety tool joint upset. HD barrels incorporate double standard outer tube thread connections to enhance the strength of the tool. HD coring barrels are available in standard 30 foot lengths. The HT outer tubes can be joined to form lengths 20 270ft (82m), and the HD outer tubes can be joined to form lengths to 360 ft (110m). These coring systems are fully stabilized by integral stabilizers.
The system uses inner tube Long Distance Adjustment (LDA) system. Wide LDA adjustment range facilitates accurate spacing of the inner tube in relation to the core bit, compensating for thermal expansion of inner tubes.
Features & Benefits
1. Optional safety joint assembly provides a durable threaded connection that can be broken easily on the rig floor to expedite core retrieval. Standard HD barrels have a top sub.
2. Swivel assembly permits maximum free rotation for maintaining penetration rates and smooth core recovery. Mud flow through the core barrel is optimized to control coring hydraulics and maintain circulation.
3. Mud lubricated thrust bearing with tempered ball bearings eliminates need for surface lubricating devices. Ball bearings, unaffected by bottom hole temperature or pressure, enable hot hole or high pressure applications.
4. A pressure relief plug permits the operator to circulate a prescribed volume through the core barrel prior to coring, ensuring a clean inner tube and hole before coring begins.
5. When seated in the relief plug, the steel drop ball diverts drilling fluids through ports above the inner tube, causing mud flow between inner and outer tubes. This minimizes core contamination and maintains circulation to the bit for proper cleaning and cooling.
6. Long Distance Adjustment system enables correct positioning of the inner tube above the core head. A wide range of adjustment easily compensates for differential thermal expansion when using aluminum or fiberglass inner tubes.
7. Inner tube stabilizers provide optimum stabilization and improved stiffness of the inner barrels when long core barrels are configured.
8. Outer tube stabilizers provide a ribbed sub to reduce core barrel/outer tube contact against the wellbore wall, reducing the risk of differential sticking and preventing premature core barrel wear to extend tool life.
9. Optional core jam indicator allows immediate detection of jamming core by causing an increase in standpipe. Pressure at the surface, ensuring that cores are not lost due to milling, pilot-type inner tube shoe stabilizers the lower end of the inner tube against the core bit or bit end bearing and serves as a pilot to guide the core into the catcher. Reduction of core jamming is anticipated.
10. Standard spring core catcher with tungsten carbide grit I.D. provides gripping on consolidated cores. When pulling the string off bottom, the spring catcher will break the core and prevent its loss while retrieving the barrel to the surface.
11. The HD barrel is designed to be used in motor coring applications in hole inclinations exceeding 90 degrees.
Core Barrel Specifications Core Barrel Specifications
4-3/4' x 2-5/8'
6-3/4' x 4'
8' x 5-1/4'
Core Barrel Length
Multiples of 30ft
Multiples of 30ft
Multiples of 30ft
4-3/4' x 3-3/4'
6-3/4 x 5-3/8'
8' x 6-5/8'
3-3/8' x 2-7/8'
4-3/4' x 4-1/4'
6-1/4' x 5-1/2'
Steel Ball Size
Core Size O.D.
Recommended Hole Sizes
5-3/4' ~ 7'
8 ~ 9'
9 ~ 12-1/4'
Yield Torque (ft.Ibs.)