Abstract

A review of oil recovery mechanisms is provided along with a guide for determination of dimensionless EOR scaling parameters, with emphasis on capillary number and bond number. Recent publications have presented improved correlation between core properties (as dimensionless numbers), and laboratory determined recovery factors for recovery process variation. These methods are demonstrated using groupings of fields completed in Muddy or Minnelusa Formations.

Strengths and weaknesses of the screening methods are discussed for various processes and enhanced waterflooding. The contrast of displacement and replacement processing is stressed, and sensitivity simulation shows the impact of formation thickness and oil mobility on recovery efficiency. Quantification uncertainties related to transition zone oil volume and mobility and the effective vertical height are stressed as areas for detailed discussion between field geologists and simulation engineers to minimize inconsistency in nomenclature or misapplication of input.

In presenting this review, the objective is really to illustrate the four steps required for “Reversing the Decline”: Step 1) Recognize that expectations are based on technical assessments using an accepted model; Step 2) Field results that contrast with expectations bring the model into question; Step 3) An improved model may support greater expectations; and Step 4) Projects well-supported by greater expectations will generate rate that will reverse declines. A new model requires a balanced review of the basic geology and flow character represented in the model.