Non-Magnetic Spiral Drill Collars
Non-magnetic drill collars:
NMDCs are generally flush (nonspiral). They are manufactured from
high-quality, corrosion-resistant, stainless steel. They are used
while running the magnetic survey instruments to be located in a
NMDC of sufficient length to allow the measurement of the earth's
magnetic field without magnetic interference. Survey instruments
are isolated from magnetic disturbance caused by other steel
components in the BHA.
Non-magnetic Spiral Drill Collar 6.750” NC50
| Specification | | Tool Joint/Connection Specifications |
| Nominal OD | 6 3/4"(6.75") | Connection | NC50 | Bend Stress Ratio | |
| Nominal ID | 2.7/8"(2.875") | OD | 6 3/4" (6.75") | ID | 2 7/8"(2.875") |
| Material Grade | P530 | Adjusted Weight | | Average Length | 31.00 ft |
| Grain Size | ASTM | Recommended Make Up Torque | | Maximum Make Up Torque | |
| Magnetic Permeability | 1.001max | Slip Recess | N/A | Elevator Recess | N/A |
| Drift Size | 3 1/8"(3.125") | Fluid Displacement | | Fluid capacity | |
| Hardbanding | None | Inspection Criteria | NS-2 | Elongation | 18% |
| IPC | None | |
| Chemical Properties | Phosphorus <0.05% |
| Sulphur <0.03% |
| Manufacturing Criteria | API Spec7-1 |
| Drill Collar Capacities |
| Tensile Strength | 120,000 psi Minimum |
| 827 Mpa |
| Yield Strength | 110,000 psi Minimum |
| 758 Mpa |
| Impact Strength | Above 60J |
| Hardness(Brinell) | Minimum 285 BHN |
Non-magnetic Spiral Drill Collar 8.250” 6 5/8” Reg
| Specification | | Tool Joint/Connection Specifications |
| Nominal OD | 8 1/4"(8.25") | | Connection | 6 5/8" REG | Bend Stress Ratio | |
| Nominal ID | 2 13/16"(2.8125") | | OD | 8 1/4" (8.25") | ID | 2 13/16" (2.8125") |
| Material Grade | P530 | | Adjusted Weight | | Average Length | 31.00 ft |
| Grain Size | ASTM | | Recommended Make Up Torque | | Maximum Make Up Torque | |
| Magnetic Permeability | 1.001max | | Slip Recess | N/A | Elevator Recess | N/A |
| Drift Size | 2 11/16"(2.6875") | | Fluid Displacement | | Fluid capacity | |
| Hardbanding | None | | Inspection Criteria | NS-2 | Elongation | 20% |
| IPC | None | |
| Chemical Properties | Phosphorus <0.05% |
| Sulphur <0.03% |
| Manufacturing Criteria | API Spec7-1 |
| Drill Collar Capacities |
| Tensile Strength | 100,000 psi Minimum |
| 689 Mpa |
| Yield Strength | 110,000 psi Minimum |
| 758 Mpa |
| Impact Strength | Above 60J |
| Hardness(Brinell) | Minimum 285 BHN |
Non-magnetic Spiral Drill Collar 9.500” 7 5/8” Reg
| Specification | | Tool Joint/Connection Specifications |
| Nominal OD | 9 1/2"(9.5") | | Connection | 7 5/8" REG | Bend Stress Ratio | |
| Nominal ID | 3"(3") | | OD | 9 1/2" (9.5") | ID | 3" (3") |
| Material Grade | P530 | | Adjusted Weight | | Average Length | 31.00 ft |
| Grain Size | ASTM | | Recommended Make Up Torque | | Maximum Make Up Torque | |
| Magnetic Permeability | 1.001max | | Slip Recess | N/A | Elevator Recess | N/A |
| Drift Size | 2 7/8"(2.875") | | Fluid Displacement | | Fluid capacity | |
| Hardbanding | None | | Inspection Criteria | NS-2 | Elongation | 20% |
| IPC | None | |
| Chemical Properties | Phosphorus <0.05% |
| Sulphur <0.03% |
| Manufacturing Criteria | API Spec7-1 |
| Drill Collar Capacities |
| Tensile Strength | 110,000 psi Minimum |
| 758 Mpa |
| Yield Strength | 100,000 psi Minimum |
| 689 Mpa |
| Impact Strength | Above 60J |
| Hardness(Brinell) | Minimum 285 BHN |
Drill Collar Classification
Drill collars can be simply put into three categories according to
their structure and material, namely the slick drill collar, the
spiral grooved drill collar and the non-magnetic drill collar.
The slick drill collar is normally a smooth thicked-wall tube, with
a thickness in the range of 38 to 53, about 4 to 8 times of that of
the drill pipes. It is machined into a uniform cylindrical shape
and made up of plain alloy steel.
The spiral grooved drill collar is also machined from plain alloy
steel, but it is normally lighter by 4 to 6 percent than the
slicker drill collar. This kind of drill collar is widely used
nowadays because the special spiral design largely hold back of the
possibility of sticking accidents by reducing the area of contact
between the wall and the collar.
The non-magnetic drill collar is manufactured from the non-magnetic
alloy steel. As the magnetic measuring instruments can sense the
geomagnetic field when measuring the direction of the borehole, the
instruments must be kept working in a non-magnetic environment.
However, in drilling process, the magnetic rigs always affect the
accuracy of the measuring instrument. Therefore, the utilization of
a non-magnetic drill collar can ensure a more reliable measuring
result.
Drill Collars in Drilling Application
Drill collars play a vital role in drilling process. Due to the
structural features, drill collars can provide weight for drilling
purpose, which is drill collar’s one and foremost specialty.
Gravity works on a number of drill collars to offer enough downward
force needed to break rocks with the drill bit.
Apart from providing weight on the bit (WOB), drill collars also
work as a shock absorber to dampen the vibration and shaking when
drilling takes place. In this way, the drilling process can be
carried out in a much steadier state.
Thirdly, the presence of the drill collars allows the pipelines to
stay in the tensile state, while guarantees the rigidity of the
drill string under great compression. Thus, the drill efficiency
and quality are greatly improved.
In addition to the above applications, drill collars can help to
control the direction of the bottom hole assembly, avoiding the
problem of hole deviation and enhancing the performance of
drilling.
For more information please contact:
Skype: ROSCHEN.TOOL , ROSCHEN_GROUP
WeChat: +86-137 6419 5009 ; +86-135 8585 5390
WhatsApp: +86-137 6419 5009 ; +86-135 8585 5390
Email: roschen@roschen.com ; roschen@roschen.net
Website: http://www.roschen.com ; http://www.roschen.net
