Well control for slim hole wells can be split into two areas for both continuous coring and downsized conventional drilling: Kick detection/ shut-in procedures and Well killing. 1 Kick detection and shut-in procedures for slim hole wells 1.1 Need for early kick detection system Early kick detection enables the volume of influx to be minimised, … Well control for slim hole wells

Muds are a critical part of an optimised slim hole drilling system. The design of the mud for all slim wells must be closely integrated with the hydraulics program, which is in turn closely integrated with the mechanical design of the drilling, evaluation, and completion system. These interfaces are much more complex than with conventional … Muds, hydraulics and lost circulation for Slim Hole Drilling – downsized conventional drilling

Muds are a critical part of an optimised slim hole drilling system. The design of the mud for all slim wells must be closely integrated with the hydraulics program, which is in turn closely integrated with the mechanical design of the drilling, evaluation, and completion system. These interfaces are much more complex than with conventional … Muds, hydraulics and lost circulation for Slim Hole Drilling – Continuous coring

When drilling downsized conventional holes, conventional core barrels can be used. The addition of the anti-vibration technology (soft torque, thruster, Moineau motor, etc.) will improve penetration rates and reduce downhole failures in a similar manner to destructive drilling. More importantly, reducing vibrations should reduce core damage and core jamming. Experience have shown the detrimental effects … Coring in Slim Hole Wells

Minimizing Vibration – Specialy for slim hole drilling with downsized conventional or retrofit equipment, the larger relative annular clearances required to facilitate kick detection and control, low ECDs with adequate flow rate, drillpipe flexibility for directional drilling requirements etc., increase the potential for vibrations. As the hole size decreases loads due to vibrations become more … Vibration minimisation for conventional Slim Hole Drilling

For Continuous Coring Slim Hole Drilling the basic geometry of the drilling system required to facilitate wireline retrieval of cores through the drillpipe provides much of the vibration minimisation. The important vibration minimisation techniques of this system, which performs excellently in the hard rock mineral industry, are: Close annular clearance between the drill rods and … Vibration minimisation for continuous coring in Slim Hole Drilling

Over the years a standard set of API sizes have evolved to reflect the materials and manufacturing technology, operating practices, and stress analysis techniques. Drillstring design for slim hole drilling has followed the two distinct paths of destructive and continuous coring although attempts have been made to achieve a compromise design suitable for both. Much … Drill string design (slim hole wells)

Five different slim hole drilling approaches are discussed in this article. In continuous coring there was a strong drive to maximise the amount of geological information, while the shallow rotary and downsized conventional wells, with less geological involvement in the conceptual work, use conventional petrophysical evaluation. Sidetracks and coiled tubing drilling are mainly for production … Slim hole Drilling Techniques

In the past small holes could not be drilled safely and effectively. The article describes the main historical problems encountered when trying to introduce slim wells: The tri-cone rock bit, rotated from surface by a rotary table, has a low aggressiveness which requires bit weight to make it drill. In small vertical holes this resulted … Historical problems with slim hole drilling

Downsizing wells has environmental benefits. During drilling the volume of cuttings, waste mud and cement are reduced roughly in proportion to the square of the hole diameter at total depth. Once slim wells are accepted in an area, the size of wellheads, blowout preventers, masts, draw works, mud pumps, mud tanks, storage bins, pipe racks, … Environmental impact of Slim Hole Drilling