this article describes the main issues to address when setting up a material suport base for drilling operations

1 Location

Offshore operations

• Good access for supply vessels at all states of the tide, i.e. ideally 5m of water at low tide.
• Sufficient wharf space for at least one, but preferably two, supply vessels (75-100 m per vessel) alongside, and sufficient yard space.
• A surface good enough to allow vehicles to manoeuvre in the expected weather conditions. A section near the edge of the wharf should have sufficient bearing capacity for barytes, bentonite and cement silos, and associated equipment.
• Accessibility by helicopter, even if it is not used as the main helicopter base. Note that this implies the provision of a helipad.
• Road access for material arriving by airfreight and/or commercial shipping routes, and/or for personnel. (Alternatively material can be trans-shipped to barges rather than being trucked in, and personnel can fly in.)
• If there is sufficient water depth for ocean going freighters that is an advantage, so that the possibility exists of delivering casing, cement and mud chemicals direct to the base without trans-shipment.
• If there is mains electricity that is an advantage, otherwise a generator must be provided.
• Similarly it is an advantage to have living and office accommodation of adequate quantity and quality which can be rented in the vicinity. Otherwise Porta-cabins have to be provided, including supplying fresh water and possibly chemical toilets.

If possible it is better to avoid major ports which are prone to problems arising from:

• An obligation to use members of a dock-workers union, who are often not willing to be flexible on working hours etc.
• The bureaucracy involved in clearing vessels in and out, combined with possibly restricted working hours of the port office.
• Requirements for pilots
• Restricted access for non-port-workers.
• Objections by other users to the dust produced when bulking cement, etc.

If several sites are suitable priority should be given to a base with good facilities which gives the shorter sailing time to the drilling unit.

Land operations

Normally the rig, casing and consumables will be entering the operating area by sea, and will be trucked to the drilling location, with the casing, chemicals and equipment being consolidated in a materials base. The materials base can be either on the coast at the port of entry (or beach), or at the drilling location itself, or anywhere in between.

Factors to take into account when making the choice of location are:

• The cost of trucking material which may never be required to the base.
• The time required for re-supplying the rig from the base, taking into account expected weather and road conditions.
• Having the materials base at or near the drilling location will probably require additional, independent, accommodation and airstrip or helipad.

In a helirig operation the critical factors are the carrying capacity of the helicopter and the cost of flying time. The helicopter base will be located at the closest point to the drilling location which can be reached by heavy transport and will normally be combined with the materials base.

2 Storage space requirements

Binned Items

Approximately 200 metres of storage are required per thousand binned items. This corresponds to an area of shelving of about 90 square metres. Where drawer racks are used for small items, the required shelving space may be reduced by a third.

The total warehouse floor area required for binned items is approximately 28 square metres per thousand items. This figure comprises 12 m2 for racks, 13 m2 for aisles and 3 m2 for bulky items too large to be accommodated on shelves.

The estimates are based on:

• Single tier racks of 45 cm deep shelving, bolted back to back in pairs.
• An average of 900 square cm per item (45 X 20 cm.) and eight "working" shelves per rack.
• Transverse aisles 90 cm wide between racks, and a single longitudinal main aisle 180 cm wide.
• An allowance of 25-30% of the floor space actually occupied by racks for bulky items which will not fit on shelves.

Floor space for bulk material

Space will be required for bulk items like cement, barytes, bentonite, lime, salt, LCM, caustic Soda and oil. Approximately 1000 m2 will be required.

Ground space for tubular

• In determining space requirements for tubulars, the following points are being considered: height of stack, diameter and range of pipe, total footage, size of pipe racks and working space.
• In accordance with API recommendations the stacking height should not exceed 10 ft including the pipe rack. For calculation assume 50 cm for height of the rack above the ground and a separation of 5 cm between the layers.
• For small quantities, particularly of small diameter pipe, it is impracticable to build a stack to the maximum height.
• Allowance must also be made for miscellaneous items such as drill collars.
• The length of each pipe rack should be sufficient to accommodate Range 3 (11-13 m) tubulars and the width should be between 6 and 12 m.
• A lane not less than 6 m wide should be allowed on either side of the racks for transport and handling, with a space of approximately 1.5 m between racks.

3 Movables and yard space

Space requirements for the balance of material normally held in Movables, or in a Yard cannot be determined in advance on an "area per unit" basis, due to the variety of material involved. However, in considering the total storage area required, this material must be taken into account. One possible approach is:

Movables and bulk material

The warehouse floor area for those Movables and Bulk items which require covered storage (e.g. fishing tools, rock bits, etc.) can be taken as approximately equal to the area required for binned items.

In the early stages of a venture when investment in buildings is kept to a minimum, all this material may have to be stored in the main warehouse. Since, from section 2, floor space per thousand stock items is estimated as approximately 28 square metres a total of about 56 square metres per thousand items would, therefore, be required when Movables and Bulk items are included. Allowance should be made also for the larger receiving area which might be needed.

Yard space (excluding tubulars)

Minimum requirements for general yard material (excluding tubulars) may be considered as equal to the combined area required for warehouses and pipe racks.

4 Total area required for a new venture materials complex

For a one string drilling programme, an area of 12,000 m2 is adequate for both warehouse and yard stocks. This should be considered the minimum requirement, and circumstances will determine whether a much larger area is required in order to take care of future expansion