Summary
Identifying compartmentalization and understanding reservoir structure are
of critical importance to reservoir development. Traditional methods of
identifying reservoir compartmentalization, such as drillstem tests and
extended well tests, often become impractical in deepwater settings, with costs
approaching the costs of new wells and emissions becoming increasingly
undesirable. Thus, compartments often have to be identified by some other
means.
Individual formation-pressure measurements, downhole fluid analysis (DFA),
and geochemistry are known to provide important information about reservoir
architecture. When these powerful methods are combined systematically and
applied to data sets, the resulting synergy delivers a much more accurate and
robust picture of the reservoir. In this paper, we review a number of case
studies in which we have successfully combined continuous fluid/facies mapping,
pressure-gradient measurements, DFA, and geochemistry for a
reservoir-continuity assessment in a diverse range of geological settings,
including a wide range of field sizes, structural environments, reservoir
lithologies, and oil types. Particular emphasis is placed on comparing the
strengths and limitations of the different techniques in revealing reservoir
architecture, especially vertical-permeability barriers. We present a number of
unambiguous cases, for which multiple data streams might be viewed as being
somewhat redundant. More-ambiguous cases, in which the multiple data streams
are required to make a robust assessment of key reservoir properties, are also
presented.
Using Fluids To Understand Reservoir Architecture
Identifying compartmentalization and the presence of fluid-flow barriers,
and unraveling reservoir architecture are critically important to reservoir
management. Misinterpreting flow compartmentalization can result in large
errors in production parameters, such as drainage volume, flow rates, well
placement, sizing of facilities and completions equipment, and production
prediction. Traditionally, drillstem testing or extended well tests are the
preferred methods to test for compartmentalization in exploratory wells.
However, in a deepwater well or similar setting, these techniques are
inordinately expensive and are also environmentally unfriendly. Moreover,
interpretation of well-test responses in turbidite and multichannel reservoirs
can be complicated by the complex reservoir architecture (Haddad and Cribbs
2002). Thus, before the final investment decision on capital-intensive
deepwater developments, compartments often have to be identified by some other
means. During exploration and early appraisal phases, various techniques, such
as geochemical fingerprinting (Edman et al. 2001; Westrich et al. 1999), can be
integrated with geologic data to better assess reservoir continuity and/or
compartmentalization before field development commences. From these data and
geologic models, reservoir simulations can be performed to best understand oil
recovery, and subsequent reservoir management can be put into place to best
capture reservoir complexities and nuances associated with almost every
deepwater field [e.g., papers on deepwater Gulf of Mexico fields: Typhoon (Ring
et al. 2004); Tahiti (Carreras et al. 2006); and Boris (Coludrovich et al.
2004)].
© 2008. Society of Petroleum Engineers
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History
- Original manuscript received:
16 October 2006
- Meeting paper published:
24 September 2006
- Revised manuscript received:
26 August 2007
- Manuscript approved:
9 September 2007
- Version of record:
25 February 2008
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