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A class act to follow

T3W drill rig

In 2006, the T3W and TH60 underwent updates on several components, some of which are apparent at first glance and others not so obvious. Today, we call models engineered before this upgrade ‘classic’ T3W and TH60 rigs, while the new versions simply have an additional designation indicating pullback weight of 40K for 40,000lb (18,144kg) or 70K for 70,000lb (31,751kg).

One of the reasons we were compelled to improve the efficiency of the drill rig systems was to address the increased heat-rejection and cooling needs of current diesel engines as a result of new US emission requirements. We needed to be proactive to avoid a never-ending upsizing of our engine installations.

A big visual change in the drill rigs is the larger sheaves in the 40K and 70K towers, which increase cable life and efficiency. Two additional tower updates add versatility: the 20in (0.5m) table opening for larger casing and a 30K (13,608kg) winch option.

Another easy-to-spot update was the move away from pneumatic regulation on the air-end to an Electronic Air Regulation System (EARS). The EARS circuit enables better airflow control. For example, the rigs can take a 1,070cfm compressor down to about 160-180cfm, which is good in soft formations.

The T3W and TH60 towers evolved separately over the years. With multiple iterations of the same item there is a tendency for special products to get lost or left out of engineering efforts. Commonality of the two new towers guarantees that any update will benefit both rigs.

Perhaps not as easy to spot, but quite significant, is the incorporation of pressure-compensated, and load-sense valves and pumps into the hydraulic system and fan-control circuit. The fan-control element of the EARS system more precisely controls the fan speed to the cooling requirements of the compressor and hydraulic oil on both drills, in addition to engine cooling on the T3W. This reduces wasted horsepower by only running the fan at the speed dictated by cooling requirements. The fan circuit now has a dedicated fan pump, which is pressure-compensated to improve efficiency.

The single-largest consumer of horsepower on the drill is the air-end and it drives engine selection more than any other component. We offer the ‘in/out box’ on T3W and the power take-off clutch on the TH60 to disengage the air-end from the engine not in use. This can save upwards of 100hp while mud drilling or tripping pipe, and can be a significant energy saving, depending on hole depth. There is a tendency not to disengage the air-end on shallow holes because of the time it takes, but those cost savings will add up over time.

The classic 30K units used five pumps to do what we can now do with three. On a new 40K drill, the current main pump supplies oil for the set-up functions, jib and winch controls, table slide, carousel, breakout, rod spinner, water injection, and the fast and slow feed.

The fan circuit also uses a dedicated pump and motor, while the rotation circuit has a dedicated pump and motor. To reduce the number of pumps in the circuit – and increase hydraulic efficiency, feed and winch speeds – we chose to use load-sense pumps.

Another significant benefit that this provided is the ability to idle the machine down and still provide enough oil to run the casing hoist or fast feed. On the classic machines those functions ran with fixed displacement pumps, and the engine ran at full rpm to quickly trip pipe with the rotary head or casing hoist. With the fixed displacement pumps dumping over relief valves, the rig was consuming a lot of horsepower. All five pumps were spinning at maximum rpm and pumping oil over reliefs or running through directional control valves.

Pump operation is totally different on the new T3W and TH60. The load-sense pump will not flow oil for which there is no specific requirement. Pressure will build in hoses (when one function is being used, but not another), yet for any energy to be consumed the oil must flow through that function.

The basic horse-power equation for hydraulic pumps is hp = psi x gallons/min ÷ 1,714. If you look at that equation, horsepower equals pressure multiplied by gallons/min and divided by a constant 1,714; the load-sense pump drives down gallons/min towards zero, and that drives down the hp number.

There is no excess pressure building with the load-sense pump. The load-sense hoses send the maximum pressure that the system ‘sees’ back to the compensator, and the pump will build to that maximum pressure. This affects the hp equation as well by keeping that psi component as low as possible, keeping the hp down proportionally.

These new drills are not the classic T3W and TH60 drill rigs, and do not operate in the same way. Remember, the real cost-savings occur when the air-end is disconnected and the drill is idled down when tripping pipe, or even during some drilling operations.

I want to thank those drill owners who were nice (crazy!) enough to allow me to operate their brand new drills, as well as their older ones. Running both offered me the opportunity for perspective and comparison. I am impressed by the knowledge of our customers, and how open and willing they are to share. Kudos to my colleague, Tim Ledbetter, for the development of this new system. He drove the design of the drills and took the heat until they proved themselves in the field.


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