This paper reports on a comprehensive study of the CO 2 -EOR (Enhanced oil recovery) process, a detailed literature review and a numerical modelling study. According to past studies, CO 2 injection can recover additional oil from reservoirs by reservoir pressure increment, oil swelling, the reduction of oil viscosity and density and the vaporization of oil hydrocarbons. Therefore, CO 2 -EOR can be used to enhance the two major oil recovery mechanisms in the field: miscible and immiscible oil recovery, which can be further increased by increasing the amount of CO 2 injected, applying innovative flood design and well placement, improving the mobility ratio, extending miscibility, and controlling reservoir depth and temperature. A 3-D numerical model was developed using the CO 2 -Prophet simulator to examine the effective factors in the CO 2 -EOR process. According to that, in pure CO 2 injection, oil production generally exhibits increasing trends with increasing CO 2 injection rate and volume (in HCPV (Hydrocarbon pore volume)) and reservoir temperature. In the WAG (Water alternating gas) process, oil production generally increases with increasing CO 2 and water injection rates, the total amount of flood injected in HCPV and the distance between the injection wells, and reduces with WAG flood ratio and initial reservoir pressure. Compared to other factors, the water injection rate creates the minimum influence on oil production, and the CO 2 injection rate, flood volume and distance between the flood wells have almost equally important influence on oil production.

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Global energy and material consumption are expected to rise in exponential proportions during the next few decades, generating huge demands for deep earth energy (oil/gas) recovery and mineral processing. Under such circumstances, the continuation of existing methods in rock fragmentation in such applications is questionable due to the proven adverse environmental impacts associated with them. In this regard; the possibility of using more environmentally friendly options as Soundless Chemical Demolition Agents (SCDAs) play a vital role in replacing harmful conventional rock fragmentation techniques for gas; oil and mineral recovery. This study reviews up to date research on soundless cracking demolition agent (SCDA) application on rock fracturing including its limitations and strengths, possible applications in the petroleum industry and the possibility of using existing rock fragmentation models for SCDA-based rock fragmentation; also known as fracking. Though the expansive properties of SCDAs are currently used in some demolition works, the poor usage guidelines available reflect the insufficient research carried out on its material's behavior. SCDA is a cementitious powdery substance with quicklime (CaO) as its primary ingredient that expands upon contact with water; which results in a huge expansive pressure if this CaO hydration reaction occurs in a confined condition. So, the mechanism can be used for rock fragmentation by injecting the SCDA into boreholes of a rock mass; where the resulting expansive pressure is sufficient to create an effective fracture network in the confined rock mass around the borehole. This expansive pressure development, however, dependent on many factors, where formation water content creates a negative influence on this due to required greater degree of hydration under greater water contents and temperature creates a positive influence by accelerating the reaction. Having a precise understanding of the fracture propagation mechanisms when using SCDA is important due to the formation of complex fracture networks in rocks. Several models can be found in the literature based on the tangential and radial stresses acting on a rock mass surrounding an SCDA charged borehole. Those fracture models with quasi-static fracturing mechanism that occurs in Mode I type tensile failure show compatibility with SCDA fracturing mechanisms. The effect of borehole diameter, spacing and the arrangement on expansive pressure generation and corresponding fracture network generation is important in the SCDA fracturing process and effective handling of them would pave the way to creating an optimum fracture network in a targeted rock formation. SCDA has many potential applications in unconventional gas and oil recovery and in-situ mining in mineral processing. However, effective utilization of SCDA in such application needs much extensive research on the performance of SCDA with respect to its potential applications, particularly when considering unique issues arising in using SCDA in different ...

analogs of natural rocks have been used in laboratory tests concerning geomechanical and transport properties. Rock analogs manufactured by 3D printing can be used to manufacture batch of the samples with specified heterogeneity compared to natural rocks. Rock analogs were manufactured with silica sand (SS) and gypsum powder (GP) using binder jetting (BJ) as well as with coated silica beads (CSB) using selective laser curing (SLC). The uniaxial and triaxial compressive tests were conducted to investigate the strength and deformation characteristics of 3DP rocks that were quantitatively compared with natural rocks. CSB and SS specimens experienced tensile failure, while the GP specimen has shown shear failure and shear-expansion behavior. The microstructural characteristics (e.g. grain shape, pore type, and bonding form) of the SS specimen were similar to a natural sandstone (Berea sandstone reported in the literature) with a relatively loose texture. In addition, 3DP rocks were more permeable than Berea sandstone (permeability of SS, CSB, and Berea sandstone was 12580.5mD, 9840.5mD, and 3950mD, respectively). The effect of microscopic mechanical behavior on macroscopic strength and failure characteristics was investigated using scanning electronic microscopy (SEM). CSB and SS specimens could be suitable to simulate the transport behavior of the highly permeable sedimentary rocks. The GP specimen could be used to study the large deformation characteristics and creep failure mode of highly stressed soft rocks. Despite the early stage of 3DP rock analog studies, the potential applications could be expanded by controlling the physical properties (e.g. wettability and surface roughness).