Page 57 - Drilling Technology in Nontechnical Language

48 Drilling Technology in Nontechnical Language Second Edition

There will also be a detailed cost estimate for the well, broken down
into various categories so the actual costs can be later compared to the
estimated costs for each category.

Potential hazards

A list should be given of any potential hazards that the rig might
encounter. These are not drilling hazards (which will be listed in the text
for each hole section), but hazards that might be inherent to the location. For
instance, in some areas, rigs might expect to encounter extreme weather
conditions at certain times of the year. In such a case, procedures can be

given for monitoring potential storms, and under specified conditions, the
rig could be evacuated as a precaution after making the well secure.

Surface location

A location on the earth’s surface may be given by many different
reference systems. Latitude and longitude is one coordinate system.
There may also be local grids or coordinate systems that the rig has to
be positioned to. In any case, whichever coordinate system is to be used
must be specified. Also the tolerance (the acceptable error) must be stated.

For instance:

“North coordinate 112995.56 East coordinate 122473.88 using X reference
system, well position to be within 5 m of specifi ed.”

The datum level for depths must be given. This could be mean sea
level, lowest astronomical tide (MSL, LAT) or another suitable reference.
The water depth for an offshore well must be stated.

General notes

References can be made to relevant government regulations, company

policies, or oilfield standards as appropriate.
A diagram of the completed well showing all relevant design details is
usually included.

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