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Technology Applications

Sleeve-System Stimulation

Well-technology company i-TEC developed a lower-completion ball-drop sleeve system. The i-FRAC system is designed to run in either open hole or cemented applications with solids-rich fracturing fluids or for acid stimulation. In open hole, sleeves can be placed individually between packers to maximize the number of stages or be arranged in clusters to increase the number of entry points per zone. A single ball can be dropped to open up to 20 sleeves (Fig. 1). Up to 90 zones can be fracture treated with a series of ball sizes to open multiple sleeves. In a cemented application, sleeves can be run in clusters to provide multiple initiation points in each fracturing stage without the need for plugs or perforating. After fracturing, the balls are produced to surface. If required, the ball seats can be milled out to allow access for logging or restimulating. The system has only two moving parts and is rated to 15,000 psi and 350°F for high-pressure/high-pressure applications. On the Norwegian shelf, the system was able to open 56 valves in three zones by dropping only three balls. The system used different-sized balls that were pumped into the well to open all the valves in each zone.

Steerable System

Baker Hughes’ AutoTrak Curve rotarysteerable system (Fig. 2) can drill vertical, curve, and horizontal sections in one run to reduce the number of trips. The closed-loop drilling system takes commands from the surface to place the wellbore in the desired direction and inclination. The programmable system has been put through more than 10,000 hours of field testing in some of the toughest unconventional environments in North America. Combining an optimized bottomhole assembly and drill bit to maximize drilling efficiency and reservoir exposure, the system achieves high build rates of more than 15°/100 ft. Tolerant of lost-circulation material in the mud system, this rotary-steerable system does not require a special pressure drop between the pipe inside diameter and the annulus to operate. Additionally, a gamma ray detector is integrated into the tool, close to the bit, to enable precise geosteering. Using the system, the entire 8 3/4-in. section of an Eagle Ford well was drilled in one run. A total of 9,735 ft was drilled in 83 drilling hours.

Mud Cleanup

The Janus OilTec Ultra Mud Vacuum can mitigate oil spills that occur at production installations and on rigs. Grease and oil used in drilling operations can sometimes be dispersed into the sea or onto the ground around land wells, causing environmental pollution. Today, spreading mud on the drill floor, in the mud room, around mixing tanks, and at other places around the rig is considered a serious problem in the drilling industry with regard to the control of pollution and protection of the environment. This system is for use in extreme conditions, such as on the rig floor, around the substructure of drilling rigs, and at shore-based facilities for transferring liquids from a shipping container to a storage tank, or for cleaning floors or work surfaces. The compressed-air-operated Venturi-type vacuum (Fig. 3) uses a 25-gal transfer tank to provide an intense uninterrupted vacuum at the suction nozzle to pick up mud, other liquids, and solid debris. The accumulated liquid in the transfer tank can be sent to a cistern or, in the case of oil-based mud, directly into the mud-circulation system.

Subsea Pile Guiding

The first offshore pile-installation operation with the StabFrame, a subsea pilestabilizing template (Fig. 4), was completed in the Waimea field in the Campos basin offshore Brazil. Jointly developed by Large Diameter Drilling Ltd. and Menck GmbH, the template stabilizes piles in all depths required for underwater pile driving. The operation used a hydraulic hammer to drive ten 84-in. mooring piles in water depths to 140 m. The piles were required for installation of a mooring system for a floating production, storage, and offloading vessel. Steered by a work-class remotely operated vehicle, the template stabilized vertical piles in varying soil conditions. Rather than relying on a release mechanism attached to the pile, the hydraulic release mechanism allowed the pile to be driven farther into the seabed, when required, before opening the frame. In this way, the template can adjust to unpredictable and challenging seabed conditions. Despite strong currents, estimated at times to be more than 2.5 knots, deployment was continuous and the project finished without incident.

Multifracturing System

The Packers Plus StackFRAC HD Multi-Stage Fracturing System can provide multiple stimulation stages for increased access to the reservoir throughout the horizontal openhole wellbore. The system enables as many fracture stages as needed in a single system and provides control of the well stimulation with regard to depth and placement. This system works with the QuickFRAC system, a batch-fracturing technology that is a limited-entry diversion technique that uses a proprietary technology to fracture several isolated stages at one time. The RepeaterPORT sleeve is a ball-actuated, hydraulically activated flow port run in conjunction with a FracPORT sleeve or Drillable Closeable FracPORT sleeve that is isolated by RockSEAL II packers to allow specific zones of the wellbore to be fractured selectively. Multiple sleeves can be run, with the largest ball seat at the top of the liner.

Straight-Through Hot Stab

SECC Oil & Gas has introduced its straight-through, pressure-balanced hot stab. It is being specified for a series of subsea injection and pumping projects in the Gulf of Mexico to help operators improve flow rates. The Max Flow hot stab (Fig. 5) was designed to achieve high stab-connector flow rates with exceptionally low pressure drops. This hot stab has a straight-through bore with no obstacle or change of bore angle to throttle the fluid-flow rate. Measuring 1/4 to 4 in. and with zero head loss caused by directional change, the design enables high flow rates with a smaller-equivalent-diameter bore without pumping at higher pressures. The stab uses pressure-balanced technology to eliminate net forces that would otherwise push the stab out of position, creating reliable connections. A simple J-latch is used to align the ports and protect the connection against loads on the attached hose.

Drill-Through Expandable System

Mohawk Energy Ltd. and Statoil are developing an Openhole Mono Clad expandable system with drill-through capability for the Heidrun business unit. Rig installation of the equipment will occur in the second quarter of 2012. The development is focused on effective mitigation of drilling hazards encountered in reservoir sections having exposed unstable formations. The system uses a self-contained running tool that uses pistons to convert hydraulic pressure into mechanical force for tubular expansion. The system is capable of radially expanding tubulars up to 30% in a wellbore with deviation up to 45°/100 ft. The system was developed as an enabling technology for re-entry drilling of sidetracked wells in which unstable formations prevented the drilling of the horizontal section. The expanded tubular provides mechanical stability for the wellbore, allowing the operator to continue drilling into the reservoir. The integrated system includes the expansion tool, jointed pipe, connectors, external seals, and anchors.

Variable Buoyancy

Ecosse Subsea Systems works with Aubin Subsea to apply their GLS lifting system. The lift system enables installing and recovering structures in subsea environments. The concept uses Aubin’s DeepBuoy environmentally acceptable low-density fluid that can act as “pumpable” buoyancy. The 550-kg/m3 density provides approximately pound-for-pound lift. By use of Archimedes’ principle, this fluid can be used to create a buoyant force on a submerged object. The pumpable flotation gel can be used in water depths to 3000 m. Because the gel is virtual incompressible and stable, there is no change in buoyancy with changes in depth. The pumpable fluid can be added and removed subsea and is nonhazardous and environmentally responsible. The system is capable of lifting large heavy structures from the seabed to near surface (and vice versa) and is suitable for installing wellhead trees, manifolds, and spool pieces. The system provides controllable lift for remotely-operated-vehicle construction work, such as spool-piece connections, riser-buoyancy installation, decommissioning, and recovery of lost components.

Wellbore-Flow Detection

Weatherford’s Microflux advanced-flow-detection system identifies fluid influxes and losses early to minimize risk and enhance drilling efficiency. The system minimizes the risk of catastrophic well-control incidents by identifying minute influxes and losses with a degree of precision that is not attainable with conventional detection equipment. The system can distinguish between various wellbore events to help avoid a misdiagnosis that can lead to unnecessary expenditures, can customize a response to a given event, and can determine whether a response is necessary. When used in deepwater environments, the system enables detecting a gas influx before it ascends to the riser, allowing adequate time to manage it effectively. The system has three primary components: a rotating control device, a mass flowmeter, and an intelligent control unit (ICU). The integration of these hardware components into one system, combined with the proprietary software in the ICU that analyzes input data, makes the system a highly effective wellbore-monitoring and -management tool.