Coupled Geomechanical Model and 3D Dynamic Flow Simulation for the Potential CO2 Injection into Deep Aquifer Siluro-Devonian Carbonate Formations, Delaware Basin

Abstract

One of the main foundations for increasing trust in geological carbon dioxide (CO2) sequestration is a geomechanical application. A complex geological process for long-term CO2 storage in deep aquifer carbonate formation would irreversibly change the assumed stable state of the sedimentary basin that evolved over millions of years. The proposed project is expected to sequester 13 MMSCFD of CO2 and H2S into Devonian and Silurian formations deeper than 16,000 feet below Lea County in New Mexico's Delaware Basin, a sub-basin of the Permian. The intensive integration of geomechanical parameters and 3D flow simulation can provide insights into storage mechanisms, migration patterns and effects on caprock integrity over 30-year injection and 100 years of shut-in. This research illustrates the comprehensive development of a 3D structural framework on interpreted surfaces and spatial variability of porosity and permeability. The dynamic flow is subsequently furnished with the boundary parameters of relative permeability, geochemical fluid components, temperature, pressure, and injection rate to simulate gas accumulation and diffusion trends. Furthermore, the findings of geomechanical rock properties and strengths are incorporated into the dynamic model to evaluate further the impact of CO2 flow on Woodford caprock stability across injection and shut-in times. Through 3D dynamic simulation, it is estimated that gas storage could reach 7.04 million metric tons with a maximum daily injection rate over the course of 30 years. The gas plume would migrate around 834 acres in the planned sequestration zone, or a radius of 0.64 miles from the injection well. The coupled geomechanical model and CO2 flow assist in exploring the caprock failure on Mohr-Coulomb circle analysis, shear, and tensile safety factors in both spatial and time dimensions of dynamic flow simulation. Despite the thermal effects, stress changes, and geochemical interactions that occur over the injection period, the caprock retains its elastic modulus and is assessed to be far from failures. The study involves solving equations of motion and stress-strain relationships to determine how the caprock will respond to changes in pressure and fluid flow. The exceptional durability of Woodford Shale seal rock will promote the success of the CO2 storage in aquifer Siluro-Devonian carbonate rocks underneath New Mexico and pave the solid way for further long-term CO2 injection wells across the Delaware Basin in the coming decades.