Page 16 - Offshore Well Construction
P. 16
CHAPTER 12
Drilling Problems
Petroleum Extension-The University of Texas at Austin
INTRODUCTION
Drilling problems cover nonroutine events such as:
• Well control
• Stuck pipe
• Fishing
• Lost circulation
• Hole stability
• Hydrates
• Mud contamination
• Hole cleaning
• Formation damage
Well control and stuck pipe will not be covered in this manual. Some of the above subjects have been covered in earlier
sections of this manual and will not be discussed further.
The key to dealing with drilling problems is to be aware of what is likely to occur and to have contingency plans and
equipment in place to effectively deal with them.
FISHING
There is a multitude of fishing tools available to cover a whole range of scenarios.
However, the single most important rule is to always have sufficient fishing equipment available on the rig to make a
first attempt at fishing any tool that is run in the hole. To accomplish this, it is important to have a detailed drawing of
all tools, including wireline logging tools that show outside and inside dimensions.
Of course, if logistics is an issue then additional equipment can be held on site.
A typical fishing equipment list includes
• Overshots
• Sufficient grapples (spiral and/or basket) to cover all sizes plus over and undersize
• Overshot lip guides and extensions
• Fishing jars and accelerators
• Bumper subs
• Taper taps
• Safety joints
• Reverse circulating junk baskets
• Mills
Always ensure that the dimensions of any fishing tools are recorded prior to being run in the hole. DO NOT RELY ON
GENERIC SCHEMATICS FOR MEASUREMENTS. This applies also to replacement tools (crossovers, etc.).
Always ensure that all relevant personnel are aware of how particular tools operate.
Always ensure that tools have been redressed correctly prior to being run in the hole. If possible, perform a function check.
Always ensure that fishing tools are included on preventative maintenance routines. All elastomers (e.g., overshot
packers) have a finite shelf life. Ensure that they are stored correctly and replaced regularly.
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