Vertical effective stress as a control on quartz cementation in sandstones

Abstract

Temperature-controlled precipitation kinetics has become the overwhelmingly dominant hypothesis for the control of quartz cementation in sandstones. Here, we integrate quantitative petrographic data, high spatial resolution oxygen isotope analyses of quartz cement, basin modelling and a kinetic model for quartz precipitation to suggest that the supply of silica from stress-sensitive intergranular pressure dissolution at grain contacts is in fact a key control on quartz cementation in sandstones. We present data from highly overpressured sandstones in which, despite the current burial temperature of 190 °C, quartz cement occurs in low amounts (4.6 ± 1.2% of bulk volume). In situ oxygen isotope data across quartz overgrowths suggest that cementation occurred over 100 Ma and a temperature range of 80-150 °C, during which time high fluid overpressures resulted in consistently low vertical effective stress. We argue that the very low amounts of quartz cement can only be explained by the low vertical effective stress which occurred throughout the burial history and which restricted silica supply as a result of a low rate of intergranular pressure dissolution at grain contacts.

Overpressure and its positive effect in deep sandstone reservoir quality of Bozhong Depression, offshore Bohai Bay Basin, China

“…Ramm et al (1994) predicted the porosity in Norwegian Continental Shelf and summarised the positive correlation between fluid pressure and porosity. This positive correlation between porosity and overpressure has been proved in the researches of the central North Sea (Kugler et al, 1990;Haszeldene et al, 1999;Lander and Walderhaug, 1999;Osborne et al, 1999;Yardley et al, 2000;Lubanzadio et al, 2002;Wilkinson et al, 2006;Goulty et al, 2012;Nguyen et al, 2013;Grant et al, 2014;Sathar and Jones, 2016;Stricker et al, 2016b;Oye et al, 2018;O'neil et al, 2018).…”

A Diagenesis Model for Geomechanical Simulations: Formulation and Implications for Pore Pressure and Development of Geological Structures

“…Quartz cementation is the primary chemical process route by which porosity is lost in sandstones (Taylor et al, ; Worden & Morad, ). Silica for quartz cement can come from several sources but is most commonly sourced internally within sands, from intergranular pressure dissolution at styolites or at individual grain contacts (Oye et al, ; Walderhaug, ). The rate‐controlling step for quartz cementation of sandstones is most commonly assumed to be the precipitation of silica (Ajdukiewicz & Lander, ; Walderhaug, , ), although others have suggested that effective stress plays an important role (Osborne & Swarbrick, ; Oye et al, ).…”

“…Silica for quartz cement can come from several sources but is most commonly sourced internally within sands, from intergranular pressure dissolution at styolites or at individual grain contacts (Oye et al, ; Walderhaug, ). The rate‐controlling step for quartz cementation of sandstones is most commonly assumed to be the precipitation of silica (Ajdukiewicz & Lander, ; Walderhaug, , ), although others have suggested that effective stress plays an important role (Osborne & Swarbrick, ; Oye et al, ). In this scenario, the kinetic barriers which inhibit quartz precipitation are overcome, on geological timescales, at temperatures around 70 to 80 °C (McBride, ; Walderhaug, ; Worden & Morad, ), above which rates of precipitation increase exponentially with temperature (e.g., Walderhaug, ).…”

Chemically Active Elements of Reservoir Quartz Cement Trace Hydrocarbon Migration in the Mahu Sag, Junggar Basin, NW China

“…Studies have shown that strata through which fluids have migrated experience strong physical and chemical interactions between fluids and rocks, which then lead to changes in the composition, morphology, and other aspects of the rocks and minerals [34][35][36]. As such, these interactions can leave a record of the processes, direction, and strength of fluid migration [37][38][39][40]. When hydrocarbon-bearing fluids migrate in strata, organic inclusions can form in authigenic minerals in reservoirs.…”