Surgil ESIA Report - Volume III - EKN

Surgil ESIA Report - Volume III
Figure A.1: Surgil Field Wellhead
Source: MML
Well control equipment is sited at a minimum distance of 25m from the well and flares for abnormal
operation / maintenance periods are provided at a minimum distance of 100m from the wells.
A.2.2.
Drilling Muds
The drilling process will use drilling fluids/muds to remove drilled cuttings (rock chippings) from the wellbore
and control of formation pressures. The drilling fluids will also seal permeable formations, maintain well
bore stability, cool and lubricate the drill bit, and transmit hydraulic energy to the drilling tools and bit.
Both water-based drilling fluids (WBDF) and non-aqueous based fluids (NABF) (with bentonite clays as a
thickener) will be utilised. WBDF will be used for the first 50m of the well bore and NABF for depths below
50m. The use of NABF is required due to the geological characteristics of the ground through which the
drilling will advance, with the NADF acting as a greasing additive to improve the drilling process by
reducing freeze-in danger, increase chisel operating efficiency and decrease hydraulic resistance.
Additional reagents, including caustic and ash soda, graphite and other reagents, will be added as required
to achieve the required properties for drilling depending on the nature of the strata through which the well
bore is being advanced.
Table A.2 provides a summary of the drilling mud components to be used for a Surgil well, by well interval.
254793/RGE/GEV/03/01/03/08/2011
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