New Rheological and Porosity Equations for Steady-state Compaction

Diagenetic theory, as it is often stated, is formally incomplete in the sense that it contains more dependent variables than the number of equations in the theory. Heretofore, this situation has been resolved ordinarily by introducing an empirical equation for porosity, , or equivalently the solid volume fraction, s 1 , as a function of depth. In contrast, the theory of compaction, that is combined momentum and stress balances, leads to a differential equation that governs the behavior of s, thus completing standard diagenetic theory. Based on recently acquired in situ data, we advance that the steady state change in solid volume fraction, d s, during compaction is well described by a function of the change in effective stress on the solids, d ; specifically,