As energy operations face the challenge of reservoirs at ever-increasing depths, modelling the response of reservoir rocks at high pressure and high temperature (HPHT) conditions is a crucial step for successfully unlocking new resources. At these conditions, rocks can experience thermal and pressure sensitivity, as well as admit internal phase changes at the pore-solid interfaces that determine their macroscopic response to external loading. It is therefore expected that constitutive laws of Geomechanics should be enriched to accommodate such effects. In this work, a multi-physics constitutive theory for sedimentary rocks is proposed within the general framework of viscoplasticity. The viscosity of the material is assumed to be a function of the temperature, pore-pressure and energy required to alter the inter-granular interfaces. This energy is expressed through the chemical potentials of the phases involved during processes like chemical dissolution/precipitation of the interfaces or mechanical debonding. The resulting flow law and corresponding stress equilibrium are coupled to the energy and mass conservation laws, constituting a closed system of equations, which is solved using the Finite Element simulator REDBACK. A series of numerical tests for performance and calibration is then successfully performed against different types of reservoir rocks, confining pressures and temperatures (from room temperature to over 800K). We show that the mechanical response of sedimentary porous rocks at strains usually achieved in laboratory testing can be explained by accounting for the interface processes taking place at the cementitious material bonding the grains, a process that can also determine the brittle-to-ductile transition of sedimentary rocks.

随着能源运营面对不断增加的深度的储层的挑战，对高压和高温（HPHT）条件下的储层岩石响应进行建模是成功释放新资源的关键步骤。在这些条件下，岩石可能会经历热和压力敏感性，并且会在孔-固界面处承认内部相变，从而决定其对外部载荷的宏观响应。因此，预期应丰富地质力学的本构定律以适应这种影响。在这项工作中，在粘塑性的一般框架内提出了沉积岩的多物理学本构理论。假定该材料的粘度是温度，孔隙压力和改变颗粒间界面所需能量的函数。该能量通过诸如化学溶解/界面沉淀或机械剥离等过程中所涉及各相的化学势表示。所产生的流动定律和相应的应力平衡与能量守恒定律和质量守恒定律耦合，从而构成一个封闭的方程组，可以使用有限元模拟器REDBACK对其进行求解。然后针对不同类型的储层岩石，限制压力和温度（从室温到超过800K）成功进行了一系列性能和校准的数值测试。我们表明，沉积多孔岩石在通常在实验室测试中获得的应变下的机械响应可以通过考虑粘结颗粒的胶结材料处发生的界面过程来解释，