Direct measurement of the unjacketed pore modulus of porous solids. (28th November 2018)

• Record Type: Journal Article
• Authors: Tarokh, Ali; Detournay, Emmanuel; Labuz, Joseph
• Is Part Of: Proceedings. Volume 474:Number 2219(2018)
• Publication Date: 2018-11-28
• Subjects: poroelasticity -- unjacketed pore modulus -- ideal porous solid -- effective pressure dependency -- non-connected pore space; Physical sciences -- Periodicals; Engineering -- Periodicals; Mathematics -- Periodicals; 500
• DOI: 10.1098/rspa.2018.0602
• Languages: English
• ISSNs: 1364-5021

Abstract

Abstract : Pressure decline caused by the extraction of oil from deep sedimentary layers depends on the pore modulus Kpp, a poroelastic parameter that characterizes the effect of pressure change on pore volume under constant mean stress. Measurement of Kpp is difficult, however, as it requires calibration to account for fluid compressibility and compliance of the testing system. Nevertheless, knowing the easily measurable drained pore modulus Kp and adopting an assumption on the unjacketed pore modulus K s ″, it is possible to determine Kpp because these pore moduli are related. Previous work on indirectly estimating K s ″ claimed that K s ″ is strongly dependent on Terzaghi effective pressure P′ and therefore not a constant; also, K s ″ might be different from Ks, the solid bulk modulus of the major mineral constituent. We overcome the limitations of the indirect approach by directly measuring K s ″. The experiments reveal that K s ″ is indeed a constant and that for an ideal porous rock, the assumption ofK s ′ ′ = K s holds. Furthermore, a constant K s ″ implies that Kp and Kpp are functions of Terzaghi effective pressure only. These results provide a framework to accurately determine the Skempton coefficient B .