A pre-job safety meeting shall be held before pulling the core barrel through the rotary table to ensure that the Drilling and Service Contractors’ personnel understand the job and potential hazards (eg., trapped pressures and catcher failure).
Recovery - H2S
If there is any possibility of the core containing H2S, only the Drilling Supervisor, Driller, Coring Contractor and the minimum necessary number of floor men shall be present when pulling the core barrel through the rotary table. All personnel shall wear breathing apparatus until it is confirmed that H2S is absent.
Core Handling
The following procedures for handling cores shall be used:
- Cores shall be gently removed from the core barrel to avoid unnecessary breakage and laid out in order in the core trays. Unconsolidated sand shall be collected in a plastic bag and placed inside the core box accordingly.
- The cores shall be laid out in a suitable place away from the drill floor and inspected for signs of hydrocarbons (eg., oil seeps, gas bubbles etc.).
- Clean mud from core by wiping with clean cloth rags using water of same composition as that in the mud
- Mark core with two coloured parallel lines (eg., red and black drawn by indelible marker pens). Use red on the right from top to bottom, mark the black line with arrows pointing to the top 20 cm intervals.
- Match and fit individual core pieces, measure to determine recovery.
- Mark core depths at 20 cm intervals. Break core into 3ft lengths to fit core boxes padded with foam lining.
- A foot-by-foot brief lithology description shall be made by the Wellsite Geologist / or mud logger using the standard COMPANY core log sheet. To facilitate detailed description of the lithology, the chipped samples of the core can be examined at appropriate depths. To avoid damage to the core and the samples, carefully place them into the core boxes after being described.