Acta Montanistica Slovaca Ročník 11 (2006), mimoriadne číslo 1, 1-9
A new concept drilling hoisting systems rigs
Jan Artymiuk
Koncept nového systému zdvíhacieho zariadenia vrtnej súpravy
In rig constructions two nev designs have been introduced apart from the conventional hoisting system. The first one
is the Maritime Hydraulics A.S RamRig
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drilling concept, based on hydraulic cylinders as actuators powered by up to 3.4 MW
of hydraulic power in a closed loop hydraulic system. This synthesis of the well-known technology allows for the use of integrated active
and passive heave compensation, as well as the storing and reuse of energy from the lowering phase of an operation. The RamRig
concept makes mechanical brakes and clutches obsolete, since hoisting and lowering of the load is controlled solely by the closed loop
hydraulics. This decreases the number of critical mechanical components in the hoisting system to a minimum. Safe handling
and emergency shut down of extreme amounts of hydraulic power is taking care of by cartridge valves, which make rerouting of
hydraulic power possible with minor losses of transferred effect.
The second is a new land rig concept based on a patented rack & pinion drive system with a new generation of rigs which can
instantly switch between the workover, drilling and the snubbing operations. The new rig concept has a direct drive, thus no drill line.
The mobilization time is reduced as the rig has fewer truck loads, a faster rig up and a higher automation level. One land rig currently
under construction will be the world’s first single operator unit, with a full pipe handling capability and a fully automated control
system. The rig is fully equipped with the 250 T top drive which can be used for the rotation and snubbing, the purpose designed
snubbing slips and other features supporting the multifunctional well operations. The paper will focus on features related to the land
rig under construction, and how it may reduce the operational cost and improve the well performance.
Key words: drilling hoisting systems, automated control system
Introduction
The Rambing
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drilling hoisting system, [2, 3, 4, 5, 7, 8 and 9].
Hoisting and lowering with the RamRig
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is done by two hydraulic cylinders called rams instead
of the conventional drawworks and derrick. The hoisting lines are parallel, fixed length, wires with one end
anchored at the drillfloor, and the other end at the top drive (Fig. 1, 2). The lines are run over the yoke
sheaves, transforming the push from the rams to an upward lifting force to the guide dolly and the top drive.
The travelling distance and the speed of the top drive is twice that of the rams. The maximum stroking
velocity of the rams is 1 m/s, allowing the Top Drive to travel 2 m/s. The powering of the RamRig is done
by means of a central Hydraulic Power Unit (HPU) with eight to fourteen pumps of equal capacity. Any
of the pumps can give a full hoisting force, but a lower speed, which means that the power can be saved for
the majority of drilling operations. The pumps are of variable displacement type and are powered by constant
speed AC motors. An additional flow can be supplied from an accumulator, which also acts as a reservoir
when performing a passive heave compensation. The valve blocks in the system act as barriers sealing off
different parts of the hoisting system. The valves in the manifolds are of the cartridge type. In order
to evaluate the new design, which has not yet been tested full-scale, a computer simulation program has been
developed based on the lumped capacity modelling in order to forecast the performance of the integrated
heave compensation. The simulations as well as the limited running experience available for the RamRig
show good a controllability for all loads.
The Hydraulic System-Closed Loop System. [1, 9, 10, 18, 19, 20, 21, 22 and 23] A closed loop
hydraulic system normally consists of a rotating motor and a pump, forming a hydraulic transmission. The oil
returning from the motor feeds the pump and the motor speed
control is performed solely by varying
the output of the pump. The pump varies the output and suction side by
regulating the displaced oil per
revolution of the pump. A good example of the conventional closed loop system is the hydraulic top drive.
In the case of the cylinder based hoisting system, the motor of the transmission is replaced by a differential
cylinder acting as an actuator. Different from the rotating transmission, the cylinder based closed loop system
must consider a circuit returning less oil than put into the system, (which is the case when extending
the cylinder), as well as handling an excess of oil, (which is the case when retracting the cylinder). To solve
the problems connected to varying feeder conditions, a semi closed circuit was implemented. Each pump
A- and B-side in the power unit is connected to a distribution block acting as an isolation for each pump [9].
Upstream from the distribution block, all lines are connected together and directed to the hoisting system
or the top drive. The normally low-pressure side of the pump, the B-side, is connected to a charge pump
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dr. inž. Jan Artymiuk
,
University of Science and Technology, Krakow, Poland,
(Recenzovaná a revidovaná verzia dodaná 5. 10. 2006)
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