Chemical-Based Tertiary Oil Recovery from Mature Reservoirs


image of parameters that control oil recovery

SwRI scientists identify parameters that predominantly control oil recovery in numerical simulation of alkali-surfactant-polymer (ASP) chemical combination flooding. Used in the context of integrated assessments, such results can provide key support to decision making on whether a tertiary oil recovery technique is viable for a specific reservoir.



For more information, contact:
Sitakanta Mohanty
(210) 522-5185


Sponsor:  Southwest Research Institute® (SwRI®) Internal Research and Development Program
Principal Investigator:  Osvaldo Pensado, Ph.D.

Program Brief

Statement of Problem: Tertiary oil recovery (TOR) technologies (e.g., thermal, microbial, chemical) are used to extract oil after secondary recovery (e.g., water flooding) has reached its economic limit. The currently sustained higher price of crude oil has presented an economic incentive for implementing inherently more expensive TOR technologies. TOR technologies, however, are fraught with significant technical challenges and many uncertainties that affect cost-effective implementation. Further research and development are needed to overcome challenges to significantly improving the recovery of the remaining oil in place and reducing uncertainties so investment decisions can be made with greater confidence.

Approach and Accomplishments: SwRI scientists used numerical modeling to develop insights into the interplay of governing chemical TOR (i.e., CTOR) processes in sandstone and carbonate rocks. The study evaluated several chemical injection modes to potentially maximize oil displacement and ultimate oil recovery using a mechanistic multiphase, multi-component, multi-dimensional computer model. Using simulated core floods and surrogate data, oil displacement patterns and ultimate recovery from the alkali-surfactant-polymer (ASP) CTOR method were investigated. A probabilistic framework was used to propagate uncertainty and to conduct sensitivity and uncertainty importance analyses. Several factors were identified that control additional oil recovery and their relative importance to recovery was ranked. These factors include injection slug size and concentration, pre-flushing, salinity level, and effective polymer porosity, among others. The probabilistic framework efficiently allows a large number of model parameters to be sampled to quickly screen parameters that would dominate ultimate oil recovery. The modeling framework permits the analyst to focus on the most important uncertainties affecting the displacement process. Analysts can then readily determine where additional laboratory experiments, field data collection, and more detailed modeling studies should be focused to reduce uncertainties and, as a result, achieve optimal and economical flooding design with greater confidence in the oil recovery estimates and related profitability analyses.

Client Benefits: The integrated, probabilistic TOR modeling approach enables SwRI scientists and engineers to assist industry in developing complex TOR projects in an integrated fashion when combined with SwRI’s in-house expertise in:

  • Characterization of complex reservoirs
  • Chemical and geochemical modeling
  • Development of multiphase constitutive relationships
  • Laboratory resources


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August 07, 2014