Caprock Integrity Assessment in Fluid Injection for Enhanced Oil Recovery (EOR) Based On Geomechanics and Rock Physics Modeling Case Study Related to The Impact of Chemical Alteration, Temperature, Water Content, Pore Pressure

Abstract

Enhanced oil recovery (EOR) also called tertiary recovery, is the process of increasing the amount of recovered oil from an oil reservoir, usually by injecting a substance into an existing oil well to increase pressure and reduce the viscosity of the oil. EOR can extract 30% to 60% or more of a reservoir's oil compared to 20% to 40% using primary and secondary recovery. Some methods of EOR use fluid injection, i.e., Gas injection, Steam injection, Chemical injection, and CO2 injection.

The strength of caprock rocks plays an important role when the fluid injection is carried out for EOR. Knowledge of the caprock strength’s limits greatly determines the success of fluid injection EOR which based on both factors of increasing hydrocarbon production and also safety factors. The fluid injection will result in subsurface stress changes caused by increasing subsurface temperature pressure and may decrease the strength of the rock. In this paper, we show the physical and geomechanical modeling based on rock physics for modeling the caprock rock strength when the injection of fluid for EOR is done in the  reservoir. The geomechanical data of rock strength many parameters such as stress state, MohrCoulomb criteria, static friction coefficient, permeability, and also rock mechanics data various temperature. The rock mechanics data, geomechanical data in various pressures, fluid saturations and temperatures are essential in caprock integrity for steam injection EOR.

The output of the integrity assessment is essential for designing the safe fluid injection of EOR parameters, especially for avoiding the risk of fluid leaking upwards to the surface which very risky for the environment.