Technical Paper: Analysis and Flow Modeling of Single Well MicroPilot to Evaluate the Performance of Chemical EOR Agents

Society: SPE
Paper Number: 136767
Presentation Date: 2010
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Many Enhanced Oil Recovery (EOR) applications involve injection of fluids into oil reservoirs to displace and recover as much of the remaining oil as possible. Typical maturation of (chemical) EOR involves phase and compatibility testing in the laboratory, displacement experiments in cores before single or multi-well pilot trials in the field, leading eventually to full field implementation. Recently, a new technique referred to as MicroPilot has been introduced as an intermediate step to take laboratory results into the field, providing valuable data for pilot design and implementation.

The MicroPilot is a log-inject-log method executed under in-situ conditions downhole in a matter of hours. A suite of wireline openhole logs are utilized to determine the initial saturations. The test then continues with a formation tester string which can drill into open hole, cleanup and inject an EOR agent into the formation. Following injection, the suite of open hole logs are run again to evaluate the effectiveness of the flood by measuring the change in oil saturation and the dimensions of the flood. The world’s first successful test has been run in a medium heavy-oil field in the Sultanate of Oman with Alkaline Surfactant Polymer (ASP) solution as the EOR agent. Post-injection formation image logs clearly show the swept zone and an oil bank.

In this paper we take the analysis of the test a step further and present dynamic simulation modeling results using the acquired data as benchmark parameters for the history match. Grid verification using single-phase pressure transient analysis is discussed. Each phase of the test is modeled and history-matched to the acquired data. The electrical borehole image log response is matched together with the vertical saturation profile seen on the post injection NMR log. During the history match, formation parameters are fine tuned and some parameters describing the EOR displacement process in the simulator are studied in more detail. The history matching effort not only provided a consistency check for the field observed data but can also help determine a few key modeling parameters prior to possible field pilot planning.

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