RESR 464 chapter 8 drilling PDF

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RESR 464 chapter 8 drilling...

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RESR 464

Chapter 8 -Drilling

Underbalanced Drilling In conventional drilling, the drilling fluid    

brings the rock cuttings to surface stabilizes the borehole cools the bit controls the formation fluids

In underbalanced drilling, drilling fluid pressure in the borehole is less than the formation pore fluid pressure, so when the formation is drilled, fluids flow into the wellbore. Advantages of underbalanced drilling:     

Increased penetration rate and bit life. Reduced drill string sticking Minimizing lost circulation Earlier formation evaluation and production Reduced stimulation required

Risks of Underbalanced drilling:    

Wellbore instability Water inflows Downhole fires Horizontal and directional tool problems

Types of Underbalanced drilling fluids:    

Air/Nitrogen Mist/Fog Foam Aerated Fluid

Coiled Tubing - greatest advantage of coiled tubing is the capability to re-enter a love well eliminating the potential of damaging the formation or reservoir. Most are aimed at increasing production by removing sand, scale deposits and debris from wellbore or by stimulating the formation by acidizing or fracturing. Advantages of Coiled Tubing:   

quick mobilization lower cost ability to pump fluids at any time regardless of position in a well or direction of travel...