In the oil industry, it is necessary to reconcile fiscally measured
hydrocarbon production with estimated production from associated wells. This
process is known as "allocation" and is important for a number of reasons,
including accounting for field production to owners/governments, field
surveillance, and volumetric input to reservoir simulators.
Traditionally, allocation is performed on a monthly basis, reconciling the
"less-accurate" sum of the well tests adjusted by well uptimes with the
"more-accurate" fiscal measurements. This process is subject to a number of
inherent inaccuracies, including less-than-perfect well tests, lack of
knowledge of precisely when the wells were interrupted, unknown well-flow
changes, and uncertainty as to how to allocate effectively the difference
between fiscal and well-test measurements.
Ineffective allocation can lead to financial consequences caused by
inaccuracies in volumes allocated between various owners and tax regimes.
Inaccuracies can also feed through to reservoir simulators, which may be used
in corresponding decision-making processes (e.g., where to drill the next
well). These inaccuracies are generally compounded with time because allocation
is performed month after month throughout the field life cycle.
Associated with hydrocarbon accounting are key performance indicators (KPIs)
(e.g., well daily production and deferment rates).
The purpose of this paper is to describe Shell's experiences in improving
allocation accuracy and automatic KPI reporting through more-effective use of
available production data and by using a continuous, rather than a
discontinuous, hydrocarbon accounting process.
© 2011. Society of Petroleum Engineers
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- Original manuscript received:
12 April 2010
- Meeting paper published:
21 September 2011
- Revised manuscript received:
18 May 2011
- Manuscript approved:
28 July 2011
- Version of record:
14 November 2011