The effects of the underlying and overlying mud rocks on the reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids pressure during CO2Carbon dioxide injectionThe process of using pressure to force fluids down wells based on rock and fluid compressibilities have been studied using a commercial numerical simulator called CMG-GEM by Chang et al., 2011. The geological characteristics of a typical oil field near a salt diapir in the Gulf Coast basinA geological region with sedimentary strata dipping towards a common axis or centre in the Southern United States are used in this theoretical study. The authors proposed that compressible mudrock layers surrounding a target formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it would increase the compressibility of the whole storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere system, thus resulting in a lower pressure increase than would otherwise be. Consequently, the riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event of failure/reactivation of pre-existing weak or discontinuous structures would be reduced. Moreover, vertical pressure diffusion into the compressible mudrock is shown to result in slower lateral pressure propagation.