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Well costs are often underestimated, because of subtle items such as transportation. For example, trucking charges for cementing a casing string may exceed U.S. $3,000, which includes round-trip charges for two pump units and a bulk truck. Careful evaluation of these charges will provide a better estimate of well costs for the authority for expenditures (AFE).
Transportation can include charges for:
- Land-based trucks.
Long-distance crew charges via commercial or chartered airplanes may be a significant cost. Accurate estimates of transportation costs require:
- A detailed well plan.
- Knowledge of the distance to the rig from local stock points.
- Rig characteristics, such as standard equipment and crew size.
Trucking charges are computed from estimates of the number of trips, the round-trip mileage, and the per-mile cost. Current trucking costs are approximately U.S. $3.50/mile. A rule of thumb for round-trip mileage is to establish a base of 100 miles from the local stock point to the rig (round trip, 200 miles). Table 1 gives some guidelines for estimating the number of round trips to be considered on a well.
Marine charges are incurred for offshore operations and marshes. The costs include boats and any dock facilities. Current charges for boats operating in the Gulf of Mexico are summarized in Table 2.
Air charges occur for offshore operations and marshes. The costs include boats on a day-rate basis and begin at rig move-in. A small helicopter (3 to 4 passenger capacity) is required for day-to-day operations. A large helicopter is used for weekly crew damages (Table 3).