New Rig Design

In the New Rig Design segment, four new offerings address multiple needs. Global Energy Services, Nabors and Swift Drilling explain innovations added to their rig designs. Also, the first DSS 38 design semisubmersible, en route to Brazil from Keppel FELS, is described.   

Innovative structure enables fast, efficient mobility in the Marcellus  

In the Marcellus Shale, stretching across Pennsylvania, West Virginia, Virginia, New York, Ohio and Maryland, drilling contractors face challenging conditions that rival those found in the remote corners of the world. It’s not harsh weather or complex geological formations that makes life difficult for drillers, says Global Energy Services.

As the company sees it, the issue is mobility: Low-level bridges, winding roads, low-hanging utility lines and hilly terrain wreak havoc on contractors moving traditional drilling rigs within the shale play. Additionally, there are strict state road regulations on the width, height and weight of loads under transport.

Mobilizing a standard rig from drill site to drill site within the Marcellus Shale can be a monumental task, requiring extensive coordination and long lead times. Contractors still run the risk of an overturned or stuck transport vehicle as it navigates over narrow, twisting roads.

Global Energy Services’ QuickSilver Lite drilling rig allows drilling contractors to quickly and easily move rigs with increased flexibility, reduced transportation costs and fewer logistical headaches. The rig is a fit-for-purpose, 1,000-hp, 500,000-lb static-hook-load, telescoping-doubles rig with a parallelogram substructure designed for use in areas where load size and weight are restricted.

The QuickSilver Lite design makes it possible to break down, transport within 100 miles and set up in 48 hr or less, with a load size that is compliant across the various multi-state regulatory agencies that enforce highway standards in the Northeast, Fig. 1. The rig’s innovative arrangement and specially designed structural/electrical elements make rig-up and rig-down easy and fast. The rig footprint can fit on a location as small as 150 x 250 ft.

Fig. 1. Global Energy Services’ QuickSilver Lite rig can rig down and be set up within 100 miles in 48 hr or less into loads that are compliant with multi-state road restriction in the northeastern US.

The rig’s enhanced safety features include:
• All pin connections, rig systems and rig arrangements are designed for safe installation at ground level.
• The mast and substructure are self-elevating with hydraulic cylinders.
• No cranes are required for rig-up.
• There are no top drives, torque tubes or service loops to rig up and rig down. The Canrig 275-ton AC top drive is designed with a special dolly that travels on the front mast legs, which serve as the guide tracks.
• The top drive can remain in the mast during in-field rig moves.

The rig uses AC technology with 90% fewer mechanical parts than conventional DC systems for less maintenance, resulting in increased fuel efficiency and improved drilling control and performance, according to the company.

Rig offers latest performance tools 

Nabors’ latest iteration of its PACE (programmable AC electric) rig is its M-Series, a 1,000-hp AC electric rig with programmable logic controls (PLC). The driller’s console allows full control of the drawworks, top drive, mud pumps and all other significant equipment from a single location. The rig features a Canrig top-drive system that incorporates its Rockit surface rotary steerable system as an additional service when drilling directional wells. Canrig’s latest version of the Torq-Matic automated floor wrench is also installed on the rig, as is the company’s automated catwalk.

The 1,000-hp AC drawworks, which features regenerative braking, is driven by two 800-hp motors. The Loadmaster 142-ft telescoping mast is raised and lowered hydraulically. Integrated rails enable the top-drive unit to travel with the mast during rig moves. The automated BOP-handling system moves the BOP in one piece, resulting in faster and safer rig-up and rig-down.

The rigs are suited to drill single wells or multiple wells from a single pad configuration and are designed to be installed with a lift-and-roll skidding system for moving the unit on a multi-well pad. During moving, the pipe is racked in the derrick, the BOP is attached to the substructure and the rig is skidded over the next well. The backyard remains in place during the moves, which can sometimes include up to 20 wells from a single pad.

The automated floor wrench features an articulated arm and PLCs; it can be operated remotely from various rig floor locations or from the driller’s console, Fig. 1. The unit is fixed on the rig floor, and the arms articulate to make up and break out pipe at the well center or mousehole. The arm can rotate 359°. The Torq-Matic 80 provides 80,000 ft-lb of break-out torque and can handle pipe of 23⁄8-in. to 8½-in. diameter. The Torq-Matic 120 provides 120,000 ft-lb of torque. This larger model is generally used offshore and can handle pipe between 2⅞ in. and 11½ in. in diameter. A pipe profiler allows multiple torque values to be preset and selected with one touch of the controls. Once torque has been selected, the wrench will provide the precise makeup for every particular joint.

Fig. 1. Canrig’s Torq-Matic automated floor wrench can be controlled from the driller’s cabin or remotely from 75 ft.

The PowerCat automated catwalk is designed to index racked drill collars, drill pipe and casing into a center carrier to be lifted to the drill floor. Drill pipe can be lifted to the floor in as little as 20 sec. The automated catwalk can raise subs, casing up to 24 in., logging tools or utility baskets. With its remote control capability, it can be operated from the drill floor or ground level by one person.

With the Rockit service provided with the top-drive drilling system, operators can increase rate of penetration (ROP) while sliding, obtain faster tool-face settings and improve tool-face control by letting the computer control the amount of drillstring rotation. The display integrates on one screen the information required for directional control, including MWD tool-face data, MWD inclination and azimuth, pump pressure and delta pressure, Fig. 2.

Fig. 2. Canrig’s Rockit service can control drillstring oscillation during directional drilling operations.

The oscillation can be programed from a fraction of a revolution left and right to several revolutions of the drillstring and is adjusted by the operator to provide maximum rocking without affecting tool-face orientation. The operator can nudge the tool face left or right while drilling to control the tool-face orientation. The adjustments can be made while the drillstring oscillation is in progress.

Small jackup for southern North Sea  

Swift Drilling BV, a joint venture of GTI subsidiary Fabricom Oil & Gas and Van Es Group, which owns jackup barges, is developing a light offshore drilling jackup based on the Gusto
MSC SEA-2750 four-leg jackup platform, Fig. 1. The rig is aimed at marginal prospects in the southern North Sea but also could be utilized in other shallow-water areas, including Southeast Asia, the Middle East and West Africa. The rig has a five-year drilling contract from Nederlandse Aardolie Maatschappij (NAM) that includes five one-year options, and it will be delivered during the fourth quarter of 2010.

Fig. 1. Swift Drilling’s jackup is aimed at economically developing shallow-water marginal fields in the southern North Sea.

GTI said the rig is smaller and more efficient than conventional jackup rigs and will open new prospects for small fields that at first were believed to be uneconomical. The rig will allow implementation of the Dutch government’s “small fields policy,” according to GTI.

GustoMSC said that, by “rightsizing the jackup and the drilling equipment, Swift Drilling has achieved a significant cost reduction for building rigs that are able to drill in the southern North Sea. The objective is to offer clients an attractive dayrate to enable economically sound development of small oil and gas reserves.”

NAM’s focus is on slim well designs, but conventional wells are also within the unit’s capabilities. The rig can drill in water depths up to 148 ft. The hull measures 221 x 131 x 18 ft. The rig will be equipped with a GustoMSC X-Y skidding cantilever system that allows the cantilever to skid 52.5 ft longitudinally while also skidding 11.5 ft transversely to work over small fixed platforms. The cantilever is capable of handling the full load within the skidding envelope. GustoMSC is also supplying the jacking system, including the hydraulic power unit. The jackup will be fitted with a drilling rig having a capacity of 250 tons.

The entire pipe-handling sequence is automated and controlled by the driller, who initiates the sequence. PLCs carry out the operational sequences with interlocks to avoid collisions and dropped pipe. A gantry crane lifts the individual drill pipe joints from the box and places them on the catwalk. A pipe-handling arm lifts the pipe from horizontal to vertical. An iron roughneck makes up and breaks out the pipe.

Deepwater semisubmersible for Brazilian drilling  

Brazilian company Queiroz Galvao Oleo e Gas (QGOG) took delivery in October of the Gold Star, the first DSS 38-design semisubmersible, from Keppel FELS’s Singapore shipyard, Fig. 1. The rig was en route to Brazil following delivery. QGOG also has a second DSS 38 rig, named Alpha Star, under construction at Keppel FELS in Singapore for delivery in mid-2011.

Fig. 1. Keppel FELS and Marine Structure Consultants’ Gold Star semisubmersible is the first of the DSS 38 design to be delivered.

The rig is rated to drill to 30,000 ft below the mudline in up to 9,000 ft of water. The compact design has a main deck that is 228 ft square with a total variable load, including deck and column load, of 5,622 tons. The derrick, crown-mounted compensator and traveling block are each rated at 2 million lb. The rig features four 2,200-hp mud pumps. Rounding out the equipment is a 21-in.-OD riser system and an 18¾-in., 15,000-psi BOP. The rig has accommodations for 130 persons.

Automated pipe-handling equipment, pipe feed and stabbing equipment are installed on the rig, with manual override for redundancy. The rig also features vertical and horizontal riser storage with a knuckle boom crane for tubular handling. It has the capacity to handle 120 75-ft riser joints (9,000 ft) with a pipe storage area of 520 m².

Eight 3,000-kW azimuthing thrusters keep the DPS-2 dynamically positioned rig on station. Power is provided by 10 3,560-kW diesel-generator sets and one 750-kW emergency generator that comply with the American Bureau of Shipping’s DPS-2 requirements for redundancy.

The storage capacities include 550 m³ of bulk mud and cement; 1,000 m³ of liquid mud; 458 m³ of synthetic mud; 1,430 m³ of drill water; 1,440 m³ of potable water; and 2,200 m³ of fuel oil.