NUMERICAL SIMULATION OF THERMAL CONSOLIDATION IN A CLAYEY ROCK FORMATION TOWARDS WELL PLUG AND ABANDONMENT

Abstract

At the end of a well’s lifespan, proper plug and abandonment (P&A) procedures are essential to prevent fluid leakage through the establishment of effective sealing barriers. Under certain conditions, salt and clay-rich formations, such as shales, can close around the casing and form a geological barrier. To enhance shale barrier formation, activation techniques including pressure reduction, heating, and chemical stimulation may be applied. In addition to rock creep, clayey rocks may deform through thermal consolidation, in which heating induces deformation of the rock matrix and pore fluids. This study assesses, by means of numerical simulations, the thermal consolidation induced by a heat source inside a well to be abandoned. Emphasis is placed on the impact of the permeability (from 10⁻¹⁷ to 10⁻²¹ m²) on the displacements and pore pressures generated around the well. The simulations show that lower permeability leads to higher pore pressure increases and longer times to reach the peak value.