Welltesting .. in daylight hours only ?
21 July 2005
Does anyone have any experience with challenging the assertion that,
during a welltest, first oil (or gas) can only be brought to surface
during daylight hours ???
It would seem that there are differing "rules" in place.
This precaution was very widespread many years ago, but we know that
a lot of companies have risk assessed this and either raised
dispensations or changed policy .. with mitigatins including
provision of floodlights etc.,
Do you differentiate between oil and gas, wildcats and appraisal
wells, areas of known Hydrogen Sulphide etc., etc., ?
Please share with us any information that we could use to assess the
Considering most wells initially opened to flow, first flow
brine/seawater (completion fluids) which is captured in stock/surge
tanks, filtered then discharged, and any initial hydrocarbons are
captured using the same kit prior to being flared as dead oil - is
this really a valid concern?
Perhaps the policy should be that water cut (BS&W) should be below X%
prior to going direct to flare and prior to first light. (X% being
based on the maximum water rate that the well test personnel/company
are sure will not extinguish the flare.)
As far as I am aware there is no regulations that state you cannot
flow a well at night?
In the very old days wooden derricks were powered by 'oil' lamps.
Lighting was poor and this is why wells were not flowed until day
light to reduced risk of burning down a wooden rig? Seriously this
is the most justifiable statement that has ever been explained to me
ref. why 'waiting on daylight' has evolved?
With today's derrick and rig lighting capabilities, this is more
than adequate for spotting sheens on the water and other risks
envisaged? If not extra lighting can and has been rigged up.
Each well should therefore be treated on its own merits and
individually 'risk assessment' e.g. on a prefect mid summers night
visibility and sea-state is often as good as during the day, so what
is the added risk?! Conversely if its blowing a Hooley and sea state
is difficult to see!. Then well should not be flowed unless
conditions can be viewed. Where here daylight would be the preferred
Case by case option should therefore determine and evaluate most
effective, efficient and ALARP risk based option. Flowing day or
night is however practicable, where this has been safely assessed to
be and has been executed several times to my knowledge.