This article describes the basic Drilling Standards.
The Drilling Department shall deliver a ‘fit for purpose’ wellbore, the criteria of which are:
- attainment of the required bottom hole position
- meet the planned trajectory without excessive dogleg security
- penetrate the reservoir without formation impairment
- provide hole conditions that allow attainment of high quality logs, RFT data, cores, cuttings etc.
- drill the well without injury to personnel or damage to the environment.
Depth Referencing
All depths (either along hole or true vertical or plug back /packer) must be referenced to the original Rotary Table Kelly Bushings (RTKB) of the rig which initially drilled the well (original derrick floor). Mean sea level and sea bed must also be reported.
On new wells, depths shall be recorded in feet below RTKB. On a sidetrack well depths shall similarly be recorded in feet below RTKB but shall also be referenced to the ‘original’ rig drill floor elevation. Sidetrack wells are to be named as WELLNAME (Mother bore), WELLNAME-A (sidetrack 1), WELLNAME-B (sidetrack 2),… etc.
Chemical Stocks
A sufficient quantity of mud and chemical stocks shall be available at the well site to drill the well or a portion of the well. Stocks of Barite/CaCO3/Salt shall be available to weigh up the mud in emergencies.
Drilling Equipment Requirements and Inspections
Responsibilities
The Drilling Supervisor shall ensure that all standard requirements for availability and management of equipment are adhered to in accordance with the Drilling Contractor’s and third party contracts, prior to the commencement of drilling activities and at all times the drilling activities are in progress.
Surface Equipment
Rig surface equipment requirements will be covered in the Drilling Contractor’s contract. All rig floor gauges, recorders and alarms shall be functioning properly.
Inspection of drilling lifting equipment shall be performed prior to commencement of all wells and inspected every six months.
Downhole Equipment
The provision of downhole drilling equipment will be covered by the relevant contracts between the Company and the Drilling contractor, and the Service Companies providing services not covered by the Drilling Contract. Operating daily rate and standby rate shall be specified if not already covered in the Drilling Contract.
Pressure Control Equipment
All pressure control equipment shall comply with API 53.
Kick Detection and Well Monitoring Equipment
All kick detection and well monitoring equipment shall be available and fitted on the rig as per the Drilling Contract. Mud logging units are to be pressurised.
All detection and monitoring equipment shall be fully operational. Fire and H2S drills are to be conducted weekly and reported.
Well Control Philosophy
At no time shall the hydrostatic pressure be less than the formation pressure. A minimum overbalance of 75 psi for oil wells and 150 psi for gas wells shall be maintained.
In the event of a ‘kick’, the normal method employed to kill the well during drilling shall be the ‘wait and weight’ method. But if there is no string in the hole the ‘volumetric method’ or ‘bull heading’ will be conducted and if the kick occurs in the horizontal section, the ‘Drillers’ method will be used.
For horizontal wells the normal method to kill the well is by the ‘Driller’s method’.