Abstract
The Flow Quality Indicator (FQI) is an innovative but simple approach to permeability prediction, developed in response to modeling and production accounting issues. The FQI theory is that, in its simplest form in a unit reservoir, three parameters, in combination, determine the flow quality - porosity, volume of impermeable member, Vimp, and the remaining grain volume or "permeable member", Vpm. FQI postulates that Vpm must expand or contract with variations in Vimp and porosity. This variation is demonstrated to be unique property of any reservoir.
By relating FQI to measured core permeability or an independent measure of reservoir quality, the resultant empirical relationship has been established as a simple predictor of permeability in the absence of core data.
Two empirical model types - quadratic and linear – have been developed from core data in Baram Delta and Sabah (Malaysia). Results from either type do not show significant differences but the quadratic model has been found more suitable for highly laminated thin bed clastic environments below log resolution. The linear model has a more general application in most clastic depositional settings where formation beds are close to log resolution or larger.
The FQI concept has implicit universality, as demonstrated by several successful tests in the Baram Delta (Malaysia), Brunei and the Niger Delta (Nigeria). Coefficients of the function may be fine-tuned using an FQI modeling tool. However, it has been shown that only limited fine-tuning is required for most environments.
The FQI approach offers significant advantages compared with alternative models for permeability prediction (such as the Flow Zone Indicator, FZI), namely: (1) the input variables (Vsh, Φ) can be readily determined from conventional logs; (2) permeability estimation is quick and comprehensive; and (3) the method is applicable over a wide variety of clastic geological environments.
