Physical modelling of sub-salt gliding due to fluid overpressure in underlying sedimentary strata

Abstract

International audienceThe Gulf of Mexico and the offshore Campos and Santos basins of Brazil provide good examples of sub-salt detachments, by shearing in the presence of overpressure. We have developed new physical models of such situations, including layers of ductile silicone putty, which simulated an evaporite, and fluid overpressure in porous brittle layers. We studied two configurations, in which the maximal overpressure was either beneath a single ductile layer of silicone (simulating salt), or between two such layers of silicone (simulating an evaporite sequence). The results of our analogue modelling showed that detachment faults appeared and persisted at the bases of the ductile layers, even though some ductile deformation occurred simultaneously within these layers. For models where maximal overpressure was between two ductile layers, detachment occurred mainly at the base of the upper silicone layer. On comparing our models with structures in the Gulf of Mexico or offshore Brazil, we find strong similarities, which lead us to suspect that detachment is indeed possible at the base of an evaporite sequence in nature. This conclusion has strong implications, not only for the understanding of petroleum systems, but also for better management of petroleum productionin sedimentary basins

Dynamic Prediction Model for a Lifecycle Process of Multi-Layer Oil Reservoir in porous media

“…In order to enhance the production of a single well, MLCP has become one of the most essential technologies in the exploitation of multilayer reservoirs. However, the depositional environment may have a tremendous impact on the petrophysical characteristics of the formational rocks, notably permeability [1][2][3]. The MLCP seepage mechanism is complex since the physical properties of each layer vary substantially due to the high heterogeneity [4][5][6].…”

Present-day overpressure in southern Tunisia: Characterization, possible causes and implications for drilling operations

“…Overpressure has been commonly detected around the world. This abnormal pore pressure is needed in oilfields exploration and production (Fertl et al, 1994;Xie et al, 2001;Akrout et al, 2016;Radwan and Sen, 2020;Agbasi et al, 2021).…”

“…It can be noted that all serious historical accidents are related to overpressurised fluids, and the latest example was the Gulf of Mexico blowout recorded in April 2010. Overpressure has been described in many sedimentary basins worldwide (Hunt, 1990;Bigelow, 1994a,b;Bjørlykke, 1994Bjørlykke, , 1998Bjørlykke, , 1998Swarbrick and Osborne, 1998;Mourgues and Cobbold, 2003;Van Ruth et al, 2003;Akrout et al, 2012Akrout et al, , 2016Akrout et al, , 2016Sen et al, 2019). Several former works have studied these abnormal pore pressure mechanisms (Smith, 1971;Fertl, 1976;Magara, 1978;Osborne and Swarbrick, 1997).…”