[First Hit]

Datapages, Inc.Print this page

Role of Secondary Previous HitPorosityNext Hit and Permeability in Predrill Prediction of Total Previous HitPorosityNext Hit and Permeability in Sandstones

BLOCH, S., ARCO Oil and Gas Company, Plano, TX

The subjective nature of some petrographic criteria used to define and quantify secondary Previous HitporosityNext Hit and the inadequacy of the mechanisms invoked to explain its generation make it difficult to construct realistic retrospective models of secondary Previous HitporosityNext Hit generation. Without such models, secondary Previous HitporosityNext Hit prediction, separate from total Previous HitporosityNext Hit prediction, is reduced to the realm of speculation. Fortunately, data from a number of Previous HitsandstoneNext Hit reservoirs and targets suggest that empirical predictions of total Previous HitporosityNext Hit are possible even if secondary

enhanced Previous HitporosityNext Hit is volumetrically important. This is particularly true of sandstones in which secondary Previous HitporosityNext Hit is formed predominantly by dissolution of framework grains. Empirical predictions are based on the correlation between Previous HitporosityNext Hit and permeability (dependent variables) and a limited number of parameters (independent variables) obtained from calibration data sets or estimated from appropriate geological models.

It appears that accurate empirical predictions of Previous HitreservoirNext Hit quality in many sandstones affected by leaching are possible because the extent of secondary Previous HitporosityNext Hit and permeability generation is to a large extent a function of primary Previous HitporosityNext Hit and permeability. If secondary Previous HitporosityNext Hit and permeability are related to primary Previous HitporosityNext Hit and permeability, which are controlled by predictable geologic parameters (independent variables), then those parameters may implicitly account for the abundance of secondary Previous HitporosityNext Hit and permeability.

Whereas the empirical approach appears to be successful in Previous HitpredictingNext Hit Previous HitreservoirNext Hit quality in sandstones affected by leaching of framework grains, its predictive accuracy in sandstones whose Previous HitreservoirNext Hit quality is controlled by dissolution of authigenic cements remains to be determined. However, in many reservoirs the effect of dissolution of authigenic cements on Previous HitreservoirTop quality may have been greatly overestimated.

 

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)