Allocation, Attribution & Measurement

The allocation process models inputs and outputs on a mass component basis to provide a physical allocation of products (gas and liquid) to each field.

Due to the impracticability of each field exactly matching its hydrocarbon production to wet gas and / or stabilised crude oil quantities, a system of operational substitution applies. The difference between gas and stabilised crude oil quantities delivered and quantities produced (allocated) is termed substitution. The Tie-in party concerned must supply such metering and analysis data so that that party’s field can be allocated its share of gas and liquid products as accurately as possible. If a third party’s quantities can only be determined via subsea completion data, then appropriate procedures will require to be discussed with the Operator.

During periods of restriction, production from Alwyn Area fields (i.e., Total equity production) will have priority and priority for any third party fields will be based on a last-in, first-out principle.

The TOTAL flow measurement standard is applied to all inputs and outputs. Orifice plate systems are generally specified, but ultrasonic (or other) meters will be considered where it can be demonstrated that an equivalent performance can be achieved.

Additional quality measurements required may include composition from on-line gas chromatograph, water measurement and H2S measurement.