C2: Acceptable Risk
Person responsible:
Morten Laget
Report No.

WLSY/MoC-5-2020
Approved

Approved
Location/Facility

Schweinsteiger
May Need to be notified
Date Originated

No date set
No date set

Minor
in Schweinsteiger

Status after drilling 9 7/8" pilot hole and decision to opening up to 17 1/2"
Following the last MoC, a decision was made to continue to drill the pilot hole to TD @ 632 m RKB after identifying a shallow gas sone on LWD logs @ 331 m RKB and visible bubbles on ROV. Plan will be as follows: During drilling of 9 7/8” pilot hole no observation of bubbles was seen during drilling, or new sones identified on LWD logs. At TD the well was flow checked with seawater for approx. 2 hours. A significant decline of bubbles was observed on video and sonar in this period, indicating decreasing trend and depletion of the sone. Shallow water not suspected. Decision to move forward as per program and open up 9 7/8” pilot hole to 17 ½” on the basis the thin (0.5m) gas bearing sand lens that has been drilled is not a threat to the rig or well integrity as now depleted. Drill 17 ½” section with seawater and pump mud at connections, same as for the pilot hole. Halliburton performed a gel-test of two slurries and based on the result of this test, the surface casing will be run and cemented with a Tuned Light lead and tail with an EcoSpacer ahead. The cement blend has been tested with gel-strenght vs. gas flow.

  • Regulations & mitigating measures (0)

    Risk Assessment Conducted

    Risk register updated and actions will be closed accordingly prior to operations

    Has been Approved

    Who needs to be notified?

    Mdir due to change in discharge

Acceptable Risk

  • Risk Assessment

    Risk Not Acceptable
    Risk Mitigation
    Must be Evaluated
    Acceptable Risk
    C2

    C

    Term
    Likely to occur
    Industry Terms
    Incident could occur in North Sea Area
    Chance of Occurence
    20% - 50%
    Frequency of Occurence
    Once in 2 years

    2

    • Low Impact
    • Non Classified
    • Restricted Work Case / Medical Treatment Case
    • Oil 100 litre
      Black 10 litre
      Red 1m3
      Yellow 10m3
      Green 100m3
    • 1 day lost time - 1 MNOK to 5 MNOK
    • Operator in dialog with authorities. No mention of Wellesley.

    Probability and Impact of Event

    PROBABILITY / LIKELIHOOD OF EVENT
    C Term In Industry Terms Percentage Chance of Occurence Frequency of Occurence
    A Very Unlikely to occur Never heard of in industry 5% Once in 10 years
    B Unlikely to occur Has occured in industry 5% - 20% Once in 5 years
    C Likely to occur Incident could occur in North Sea Area 20% - 50% Once in 2 years
    D Very likely to occur Incident could occur during our operations 50% - 80% 2 times per year
    E Almost certain to occur Incident could happen more than once during this operation 80% Once a month
    IMPACT / CONSEQUENCE OF EVENT
    C Term Well Control People Environmental Damage Asset Damage Reputation Damage
    1 Very low impact Negligible First Aid Required Oil 100 litre
    Black 10 litre
    Red 1m3
    Yellow 10m3
    Green 100m3     		1 day lost time
    Less than 1MNOK    		 Information only to authorities. No further discussion.
    2 Low Impact Non Classified Restricted Work Case / Medical Treatment Case Oil 100 litre
    Black 10 litre
    Red 1m3
    Yellow 10m3
    Green 100m3     		1 day lost time
    1 MNOK to 5 MNOK    		 Operator in dialog with authorities. No mention of Wellesley.
    3 Medium Impact Regular Well Control Incidents Lost Time Incident / Reportable Incident Oil 1m3
    Black 100 litre
    Red 10m3
    Yellow 100m3
    Green 1000m3     		3 days lost time
    5 MNOK to 10 MNOK    		 Operator investigated by authorities. No mention of Wellesley.
    4 High Impact Serious Well Control Incidents Likely Permanent Disability Oil 100m3
    Black 1m3
    Red 100m3
    Yellow 1000m3
    Green 10000m3     		14 days lost time
    10 MNOK to 30 MNOK    		 Local media coverage. Wellesley included in coverage or approached by authorities.
    5 Very High Impact Critical Well Control Incidents Single or Multiple Fatalities Oil 1000m3
    Black 10m3
    Red 1000m3
    Yellow 10000m3
    Green 100000m3     		30 days lost time
    More than 30 MNOK    		 National coverage. Wellesley included in coverage.

  • Additional Documentation

    PDF File MoC-Open-up-pilot-hole-with-17.5-in-BHA-30.08.20-Schweinsteiger.pdf

    MoC-Open-up-pilot-hole-with-17.5-in-BHA-30.08.20-Schweinsteiger.pdf

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