SUMMARY
The development planning of offshore oilfields, such as in the British North Sea sector, involves a variety of platform production/injection constraints. The operation of the platforms is governed by reservoir engeering, operational and production policy considerations. This paper describes the production/injection control system as incorporated into a volatile oil reservoir simulator for use as a field management tool.
Production and injection operations are controlled at three levels in an offshore oilfield:
At the individual well level in which rates, well inflow performance, pressure constraints and well bore hydraulics play a role.
At the platform level in which well rates have to be controlled within available capacities (oil/gas/water production, gas/water injection).
At the field level in which total fluid production from the field is governed by pipeline/tanker capacity, allowing shortfall to be taken up by platforms operating with spare capacity.
To meet gas sales contracts and/or flaring constraints use is made of gas wells operating in a dual injection and production role ("gas-control wells").
Such gas-control wells enable surplus gas production to be reinjected or alternatively gas to be produced to meet a gas sales contract.
The paper further describes the possibilities of the well management package to implement a policy of voidage replacement or pressure maintenance in distinct reservoir partitions (zones). Pressure maintenance is defined as maintaining the hydrocarbon pore volume averaged pressure at datum. Such strategies interact with the total available injection capacity of the platforms and/or the distribution of capacity usage over the platforms.
