Well Construction | AirLock Casing Buoyancy System
Unique AirLock buoyancy system cuts casing running time, cost, and risk
Lateral buoyancy combined with vertical fluid weight lands casing successfully on 99.9% of first attempts.
The AirLock® buoyancy system cuts casing running time and cost significantly, without intervention and without interfering with casing and cementing operations. The system allows the vertical casing section to be filled with fluid, while the lateral section remains air-filled and buoyant. The enhanced buoyancy reduces sliding friction up to 50% or more, while the weight of the vertical section adds force to push the casing all the way to the toe.
AirLock operation is simple and passive. The seal collar is installed at a location in the casing string calculated to provide the optimum balance of lateral buoyancy and vertical fluid weight. The collar contains a high-strength, dome-shaped pressure seal supported by a calibrated shear ring with breakaway tabs. After casing lands, increased surface pressure shears the tabs, and the dome is forced into the tapered throat below, where it is instantly crushed into small fragments, leaving a completely unrestricted wellbore.
54% reduction in lateral casing weight and drag forces
|Casing weight in air||11.6 lb/ft (17.3 kg/m)|
|Casing weight in water||10.4 lb/ft (15.1 kg/m)|
|Casing weight with AirLock||4.8 lb/ft (6.9 kg/m)|
|4.5 in (114.3-mm) casing, 4-in (101.6-mm) ID; fluid in lateral casing is air; fluid in vertical casing and open hole is water|
To date, more than 10,000 AirLock systems have been run, and casing has landed successfully on the first attempt more than 99.9% of the time, including monobores and long strings in difficult, abrasive formations.
- Calibrated shear-ring design ensures predictable operation.
- No ID restriction after operation.
- Strength specifications match the host casing.
- Collar can be torqued-through.
- Collar is compact (24 in. length) for easy handling.