As a well is downsized the collapse and internal pressure ratings of the surface and intermediate casing and liner string increase. Thus liners can be used further up the hole than with conventional hole sizes. This gives the downsized conventional approach to slim wells the capability to increase the diameter efficiency of wells. 1 Casing … Casing, liners and cementing for Slim Hole Wells
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 – Continuous coring
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
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
The existence of substantial vibrations in the drillstring have caused much trouble time during drilling in slim (and conventional) holes. Minimising drillstring vibrations during the drilling of slim and conventional holes means that the dynamic components of the loads in the drillstring are reduced, with the following consequences: The peak loads can be reduced reducing … Drill string vibrations
With improved equipment and operating practices, downhole failures have decreased in all drilling operations. The cost and time to sidetrack round a fish has been substantially reduced due to improved directional drilling and surveying techniques. This is especially true for slim hole drilled with downsized conventional equipment. A sidetrack round a fish should take one … Fishing in slim hole wells
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)