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Wettability is an essential component of reservoir characterization and plays a crucial role in understanding the dominant mechanisms in enhancing recovery from oil reservoirs. Wettability affects oil recovery by changing (drainage and imbibition) capillary pressure and relative permeability curves. This paper aims to investigate the role of wettability in matrix-fracture fluid transfer and oil recovery in naturally fractured reservoirs. Two experimental micromodels and one geological outcrop model were selected for this study. Three relative permeability and capillary pressure curves were assigned to study the role of matrix wettability. Linear relative permeability curves were given to the fractures. A complex system modelling platform (CSMP++) has been used to simulate water and polymer flooding in different wettability conditions. Comparing the micromodel data, CSMP++ and Eclipse validated and verified CSMP++. Based on the results, the effect of wettability alteration during water flooding is stronger than in polymer flooding. In addition, higher matrix-to-fracture permeability ratio makes wettability alteration more effective. The results of this study revealed that although an increase in flow rate decreases oil recovery in water-wet medium, it is independent of flow rate in the oil-wet system. Visualized data indicated that displacement mechanisms are different in oil-wet, mixed-wet and water-wet media. Earlier fracture breakthrough, later matrix breakthrough and generation and swelling of displacing phase at locations with high horizontal permeability contrast are the most important features of enhanced oil recovery in naturally fractured oil-wet rocks.

The main problem during field scale implantation of low salinity water injection (LSWI) is the decline in injectivity versus time. Moreover, the actual mechanisms that result in incremental oil recovery are not completely known. In previous studies, the geomechanical effects have not been considered, and pore volume changed while bulk volume is still constant which in turn can bring uncertainty to the simulation results. In this paper, both geochemical and geomechanical models have been coupled with the flow model. For coupling geomechanical model, three equations have been solved simultaneously in each time step. Then, the geochemical model has been coupled by adding the necessary aqueous and mineral reactions and ion concentration of both formation and injection waters. Increasing the Ca2+ concentration in the injected brine cause a reduction in the ultimate oil recovery. Also, increasing SO42− concentration in the injected brine up to about 70 ppm, resulted in increased oil recovery, while increasing the concentration caused a reduction in oil recovery. Injection above formation parting pressure (FPP) is beneficial but, there is a high uncertainty during injection above the FPP that can affect ultimate oil recovery and net present value. The results of this study show that geomechanical and rock parameters have intensive effects on the simulation results and rough estimating them in the simulation process can result in major errors and uncertainties. Further, it is very important to precisely include the dominant mechanisms of low salinity or smart water process during simulation studies.

CO2 transport from capture sources to storage sites is one of the leading parts of the carbon capture, and storage (CCS) infrastructure that needs to be optimized in order to reduce the capital, operating and maintenance (O&M) costs. This paper conducts a systematic overview of CO2 transport and identifies the knowledge gaps with a view for application to optimal CCS Hub design. The findings show that much research has been focused on the engineering and economic consequences in pure CO2 streams while in most real field studies the captured CO2 is accompanied with trace impurities that can affect the "intelligent" cost model's confidence to estimate CO2 pipeline costs. The impacts of different topographical conditions in current models on the economic pressure drop and inlet pressure is another challenge that has received little attention in the literature. Most cost-effective pipeline systems described in the literature, are based on the simple point-to-point design while the capture of CO2 from multiple sources and transport to multiple distributed CCS injection wells is an issue for the industrial-scale rollout of CCS. The lack of sufficient studies on the flow variations within CO2 networks is the last discussion in this research review. Further, there have been several cost models reported in the literature, and most of them are based on the costs of the natural gas pipeline infrastructure. However, the higher operating pressure of CO2 and the various impurities in CO2 streams from capture plant may require construction material specifications that will affect cost models. A systematic understanding of how CO2 pipelines contribute to CCS chain economics is still lacking. While many optimization challenges have been solved for natural gas pipeline networks, there are different thermodynamic behaviors for CO2 that require further optimization. The potential minor impurities that could occur in CO2 pipelines such as water (H2O), nitrogen (N2), oxygen (O2), hydrogen sulfide (H2S) and methane (CH4) can add complexity compared to the transport of natural gas.

Carbon dioxide miscible flooding is known as a very efficient and challenging enhanced oil recovery (EOR) method. Besides the high oil recovery efficiency, the asphaltene precipitation and deposition is believed to be triggered by a perturbation of the thermodynamic equilibrium present in the reservoir. Asphaltene deposition results in wettability alteration and plugging in the reservoir as well as affecting the production facilities. The complicated mechanism of phase separation in asphaltene-containing systems makes it crucial to study the effects of different parameters on the aggregation of asphaltene particles. In this study, a novel high-pressure visual cell equipped with a high-resolution microscope along with the image processing software was prepared to investigate the growth of asphaltene particles on a sample reservoir rock. The quantity of asphaltene deposition was determined at several pressure depletion steps and different temperatures with and without CO2 injection. This would help to evaluate the kinetics of asphaltene flocculation resulting from CO2 injection or pressure drop due to natural depletion. The results reveal that the amount of asphaltene deposition increases with increasing the concentration of the injected CO2. The results of this study demonstrated that the molecular structure of asphaltene could have a noticeable effect on the asphaltene deposition.