This document details the minimum standards for carrying out a rig move.
1. INTRODUCTION
1. Each move shall be covered by a specific procedure agreed by all parties.
2. The rig move procedure or programme should be prepared by the contractor, wherein for offshore operations it is to be prepared by the contractor Tow Master in collaboration with the COMPANY’s Marine Rep and Well Operations Superintendent.
3. The COMPANY’s Marine Rep can be hired from a specialised contractor.
2. GENERAL
1. Land rig moves are carried out under the direct control of the Rig Contractor. COMPANY Well Operations Superintendent shall approve the rig move procedures prior to the beginning of the move.
2. Offshore Rig moves are carried out under the control of the Rig Contractor’s Rig-Mover or Tow Master.
3. The COMPANY Marine Representative shall approve the offshore rig move procedures.
4. Moves onto or close to production facilities or installations fall into the category of Combine Installation Safety Case and will require that the provisions of WOR 06 – Simultaneous Operations are followed.
5. All equipment that is to be used for a rig move onto or off COMPANY location shall have been inspected, certification checked and deemed fit for purpose.
This includes but is not limited to:
a. vessels (anchor handlers),
b. cranes,
c. trucks,
d. towing equipment
e. lifting equipment.
3. PREPARATIONS
3.1 Offshore
1. Prior to any offshore rig move the following actions shall have been taken.
2. In the case of a newly contracted rig a marine audit is required. This is optional for rigs that are already under contract and whose layout, equipment and capabilities are fully understood.
3. For moves onto existing installations, or that may pass close to existing installations, a site visit will be carried out to identify any obstacles, difficulties or preparation work required. This shall be attended by the Barge Master, Rig Superintendent and/or GDF SUEZ DEP Site Supervisor, and Marine rep (normally the rig mover).
4. For self offshore units, self elevating or Semi-sub, a site survey shall be carried out including soil characteristics.
5. This has to be done prior to the rig move when the well location is determined.
6. A Rig Move Procedure shall be prepared and agreed by all parties. Risk assessment shall be carried out to identify hazards to wells and pipelines.
7. All wells and pipelines that could potentially be damaged by any rig move operations are to be isolated and depressurised.
8. A pre-move meeting shall be held on the rig.
9. For floating well operations a mooring analysis, a worst-case wellhead bending stress analysis, and riser analysis are required.
3.2 Offshore Rig Move Procedure
1. The Rig Move Procedure includes the following as a minimum requirement:
a. Moving programme,
b. Contingency plan,
c. Responsibilities,
d. Weather forecasting,
e. Sea bed survey and location approval,
f. Positioning and surveying methods,
g. Rig position and heading on new location,
h. Anchor pattern and tension tests,
i. Pennant and chaser combinations,
j. Communications responsibilities,
k. Specification and selection of anchor handlers, tugs and other support vessels.
3.3 Onshore
1. Prior to any onshore rig move the following actions are required.
2. In the case of a newly contracted rig an audit is required. This is optional for rigs that are already under contract and whose layout, equipment and capabilities are fully understood.
3. A site visit will be carried out to identify any obstacles, difficulties or preparation work that requires to be carried out.
4. The Rig Contractor shall identify any obstacles or hazards along the route of the move such as the bearing load of bridges, adverse road conditions, power lines, etc.
5. Where necessary civil engineering expertise will be employed to ensure that load bearing per axle is within bridge design capacity.
6. The Rig Contractor shall provide a copy of the rig move plan for COMPANY Well Operations Manager approval.
7. COMPANY representative shall prior to commencement of the rig move inspect all equipment to be used including cranes, trucks, lifting equipment, chains, etc.
3.4 Onshore Moving Plan
1. The onshore moving plan shall include:
a. A list of all loads showing dimensions and weights.
b. Characteristics of cranes to be used.
2. This shall include a load chart showing maximum load versus distance from crane. Characteristics of lorries and trucks to be used. They shall be of adequate capacity be in good mechanical condition.
a. Details of the itinerary to be taken.
b. Identification of any hazards or difficulties such as bridges or culverts, steep gradients, tight corners, low power lines.
3. The plan should address any work required such as strengthening culverts, moving power lines, etc.
a. List of any approvals required for the move.
b. A plan and schedule detailing how the move is to be carried out.
4. RIG MOVE PROCEDURE DETAILS
4.1 Personnel Responsibilities
1. The responsibilities of the onboard personnel should be clearly defined, especially when the rig contract changes Operator during the rig move.
2. The responsibility of:
a. The Well Operations Supervisors on board (Previous Operator and COMPANY)
b. the Contractor Tow Master for offshore rig moves
c. The rig Manager for onshore moves and rig OIM for offshore moves
d. The previous operator Marine Rep for offshore rig moves
e. The COMPANY Marine Rep for offshore rig moves
f. The Vessel Masters (Anchor Handlers – Tug Boats) for offshore rig moves
g. The Rig Positioning Supervisor
h. The Insurance or Warranty Surveyor.
4.2 Location Details
1. Previous Location
a. Block
b. Location
c. Latitude/Longitude
d. Rig Heading on new location
e. Bathymetry
f. Spud can penetration
g. Seabed composition
h. Shallow gas study
2. New Location
a. Block
b. Location
c. Latitude/Longitude
d. Rig Heading on new location
e. Bathymetry
f. Anticipated spud can penetration
g. Seabed composition
h. Positioning tolerance
i. Shallow gas study
4.3 Rig Move Support
1. Towing Vessels details including description of towing gears specifying that they have to be in full working order, bollard pull capacity, etc.
4.4 Navigation Equipment
1. Description and justification of the navigation and positioning equipment to be installed on the MODU and on the Anchor Handlers.
4.5 WEATHER CONDITIONS
1. Weather window necessary to move off location, to transit between locations and for jack down operations when applicable.
2. This should includes details such as minimum time, wind speed, Maximum sea, Maximum swell.
4.6 LEAVING THE PREVIOUS LOCATION
1. Description of the operation, number of vessel required, headings, communication, etc.
4.7 TRANSIT
1. Description of route, transit time, sheltered place in case of unexpected problem, stand-by location.
2. A list of different legal notifications that have to be transmitted during the transit (Refer to local regulation).
3. The Group Well Operations Manager or his representative must be informed of a rig departure and it’s ETA.
4.8 ARRIVAL AT WELL LOCATION
1. When applicable permission of the platform OIM, ensure location access is clear.
2. Anchor pattern when applicable.
3. Final approach and final position.
4. Final position acceptance shall be the responsibility of the COMPANY Senior Well Operations Supervisor.
4.9 CONTINGENCY PLAN
1. Description of the applicable contingency plans during the different phases of the rig move e.g. Previous Operator contingency plan is in effect during the period where this Operator has the rig under contract, GDF SUEZ’s one will be in effect thereafter.
5. RIG JACKING
Jacking operations are the responsibility of the Drilling Contractor, however we shall ensure that correct jacking procedures and related contingency plans are in place prior to start of this important operation.
5.1 SPUD CANS
1. COMPANY representative must ensure that the spud cans are fit for purpose e.g. Skirted spud can are likely to be damaged on hard seabed. This has to be discussed with the Drilling Contractor.
5.2 PUNCH THROUGH
1. Punch through is when the seabed suddenly breaks under the load of the rig. This can happen during Preloading operations and could cause severe damage to the unit. A fit-for-purpose offshore coring programme is required to satisfy the Rig Contractor’s own insurance requirements.
5.3 SCOUR
1. This phenomenon is the alteration of the seabed due to the presence of the rig legs and spud cans. It is generated by the current or the waves in shallow water. Sediments from the seabed will be removed from around and below the spud cans having the effect of increasing the water depth over an extended period of time.
2. A good knowledge of the local sea condition will prevent such problems occurring. In severe conditions a matt supported jack-up may be considered optimal.
5.4 AIR GAP
1. The air gap is the distance between the sea level at LAT condition (Lowest Astronomical Tide) and the bottom of the hull. It must be big enough to prevent the hull being in contact with the waves in heavy storm conditions.
2. It can be calculated as follows: 100 years maximum wave crest elevation above still water + 100 years high water spring tide + 100 years seiche effect + 100 years surge effect + safety (to be determined according to the area)
3. This has to be discussed and agreed with the Drilling Contractor as they usually have their own definition and calculation method for their rig air gap.
a. A seiche is a standing wave in an enclosed or partially enclosed body of water. Seiches and seiche-related phenomena have been observed on bays and seas. The key requirement for formation of a seiche is that the body of water be at least partially bounded, allowing natural phenomena to form a standing wave.
b. Storm surge is caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea level.
6. LOCATION SURVEY
1. Location co-ordinates must be given to the surveyor in Geographical (Latitude/Longitude) and Grid (Northing/Easting) with respective references. It is very important to ensure that everybody is using the same references.
2. Bathymetry report from surveyor should show:
a. Maximum water depth within the survey area (MSL and LAT)
b. Minimum water depth within the survey area (MSL and LAT)
c. Water depth at the well location (MSL and LAT)
d. Water depth at the stand-by location (MSL and LAT)
e. Difference between MSL (Mean Sea Level) and LAT (Lowest Astronomical Tide)
f. Tide curves
g. Seabed inclination and orientation of the dip
h. Presence of previous spud can prints
i. Seabed sediments composition – Soil sampling - Coring
j. Seabed obstructions including buried objects
k. Existing installation such as pipe lines or wellheads…
l. Anchoring conditions (hardness of the seabed…)
m. Geotechnical site investigation which should contain:
n. Soil description
o. Soil parameters for spud can penetration analysis under preload conditions
p. Risk of scour
q. Risk of Punch through
r. Geophysical report:
o Stratigraphy
o Seabed features – Presence of boulder
o Presence of sandy channels where shallow gas could be suspected.