Underbalanced drilling - Sunterra Well Services

Underbalanced drilling
Underbalanced drilling is when the effective circulating
downhole pressure of the drilling fluid - which is equal
to the hydrostatic pressure of the fluid column, plus
pump pressure, plus associated friction pressures - is less
than the effective near bore formation pore pressure.
The lower hydrostatic head avoids the build-up of filter cake on the
formation as well as the invasion of mud and drilling solids into the
formation. This helps to improve productivity of the reservoir and
reduce related drilling problems.
Techniques for UBD include:
• light weight drilling fluids
• gas injection down the drill pipe
• gas injection through a concentric string
Advantages:
• Increased ROP
• Decreased formation damage
• Eliminate risk of differential sticking
• Reduce risk of loss circulation
• Less weight on bit required
• Improved bit life
• Tight hole problems may be reduced
• Reduced cutting size increasing hole cleaning capability
SunTerra Well Services
2363 Blake Street, Suite 201
Denver, Colorado, 80205
Ph: (720) 272-8332
Toll Free: 877-797-6378
Email: [email protected]
www.sunterrawellservices.com