Summary
This paper illustrates how practical application of surveillance and
monitoring principles is a key to understanding reservoir performance and
identifying opportunities that will improve ultimate oil recovery.
Implementation of various principles recommended by industry experts is
presented using examples from fields currently in production.
Practices in processing valuable information and analyzing data from
different perspectives are presented in a methodical way on the following
bases: field, block, pattern, and wells. A novel diagnostic plot is presented
to assess well performance and identify problem wells for the field.
Results from the application of these practices in a pilot area are shared,
indicating that the nominal decline rate improved from 33 to 18% per year
without any infill drilling. The change in the decline rate is attributed
primarily to effective waterflood management with a methodical approach,
employing an integrated multifunctional team.
Although the suggested techniques can be applied to any oil field undergoing
a waterflood, they are of great value to mature waterfloods that involve
significant production history. In these cases, prioritization is a key aspect
to maintain focus on the opportunities that will add the most value during the
final period of the depletion cycle. Case studies illustrating the best
surveillance practices are discussed.
Introduction
Surveillance and monitoring techniques were first discussed in SPE
literature in the early 1960s (Kunkel and Bagley 1965). Since then, several
highly recognized authors have published related materials (Thakur 1991; Thakur
and Satter 1998; Talash 1988; Gulick and McCain 1998; Baker 1997, 1998; SPE
Reprint 2003). Industry experts recommend the following valuable
principles:
- The key ingredients of any surveillance program are planning and accurate
data collection.
- To understand reservoir flows and reduce nonuniqueness in interpretations,
it is crucial to implement a multilevel surveillance effort.
- A single technique in isolation is not generally indicative because
different parameters can cause similar plot signatures.
- Controlled waterflooding through the use of pattern balancing requires time
and technical efforts —engineering and geological—during the life of the
project.
- Valuable insights into the performance of the waterflood can be gained from
individual-well plots such as Hall plots.
- Surveillance techniques should always be a precursor to in-depth studies,
including numerical simulation.
A process to consistently evaluate the performance of a reservoir—from field
to block to pattern to well level—is discussed with the help of real-life
examples. Type plots and maps are used to identify opportunities and promote
team discussions to effectively manage a reservoir undergoing waterflood.
Production history and basic reservoir characterization serve as primary input
variables for the recommended analysis.
© 2007. Society of Petroleum Engineers
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History
- Original manuscript received:
6 July 2006
- Meeting paper published:
24 September 2006
- Revised manuscript received:
20 May 2007
- Manuscript approved:
16 June 2007
- Version of record:
20 October 2007
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