Subsea Operation Expenditures (Opex)
An offshore well’s life includes five stages: planning, drilling, completion, production, and abandonment. The production stage is the most important stage because when oil and gas are being produced, revenues are being generated. Normally a well’s production life is about 5 to 20 years. During these years, both the planned operations and maintenance (O&M) expenditures and the unplanned O&M expenditures are needed to calculate life cycle costs. OPEX includes the operating costs to perform “planned” recompletions. OPEX for these planned recompletions is the intervention rig spread cost multiplied by the estimated recompletion time for each recompletion. The number and timing of planned recompletions are uniquely dependent on the site-specific reservoir characteristics and the operator’s field development plan. Each of the identified intervention procedures is broken into steps. The duration of each step is estimated from the historical data. The nondiscounted OPEX associated with a recompletion is estimated as: OPEX =(Intervention duration) x (Rig spread cost) The percentage of each cost component of the total OPEX varies from company to company and location to location. Cost distributions among OPEX components for shallow-water development are similar to those for deepwater developments, except that the cost of product transportation is significantly lower.
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