Porosity loss, fluid flow, and mass transfer in limestone reservoirs: Application to the Upper Jurassic Smackover Formation, Mississippi (Discussion & Reply)

Abstract

Heydari (2000) presents a series of calculations and interpretations based on 24 modal analyses covering a limestone interval 36 m (117 ft) thick. This is an impressive application of quantitative petrography to determine the detailed mechanisms of carbonate diagenesis. Although I reviewed this article in manuscript, I did not have the opportunity to comment on the use of a model for convective circulation of formation water, which was added after my review was completed and which now stands as the main conclusion arrived at by this study. This discussion contends that (1) the convective circulation model used to explain apparent differences in material loss and gain between different parts of the reservoir is implausible and unnecessary; (2) the calculations of porosity loss by compaction and cementation are unnecessarily inexact; and (3) the main significance of this very interesting study is entirely different from what is stated in the article. The convective circulation model is implausible because to operate it requires unrealistically high permeability throughout the grainstone layer. This can be illustrated by considering an example calculated by Bjorlykke et al. (1988, p. 348) for a bed …