Sharif Digital Repository

Changes in thermodynamic properties such as pressure, temperature, and composition may result in asphaltene precipitation and deposition in porous media. In addition, asphaltene deposition can cause wettability alteration, permeability reduction, and ultimately a decrease in the productivity of a reservoir. Natural depletion is one of the most common processes of asphaltene deposition in which pressure changes destabilize the dissolved asphaltene in the oil and settle them onto the rock surface. In this work, natural depletion experiments in consolidated core samples were performed under simulated reservoir conditions to obtain reliable data and analyze the asphaltene deposition mechanisms.... 

Scale formation is one of the major problems in oilfields. Removal of scales is a difficult process due to their relative hardness and low solubility. Therefore it is valuable to find a method which can remove damages caused by scales. Ultrasonic radiation is known have the sufficient energy to remove the scales. Our purpose is to investigate the role of ultrasound on permeability increments due to scale removal. Some experiments were carried out to find these effects and observed that ultrasound has increased volumetric mass transfer, concentration and solubility limits. We also worked on a model presented by Tahmasebi et. al[2010] and applied changes on it to make it able to predict... 

The wellbore represents one of the most crucial components in the hydrocarbon and geothermal reservoir system, as it is the sole conduit to the reservoir for fluid production or injection. Therefore, predicting and controlling of the permeability variations close to the wellbore has been one of the most challenging issues in geothermal and petroleum reservoir systems. A new method is presented to model fracture permeability changes during drilling in fractured rocks. The approach includes finite element method (FEM) for fully coupled thermo-poroelastic analysis of stress distribution around borehole and displacement discontinuity method (DDM) to model fracture deformation. Four models of... 

A gas sensor was developed to measure the concentration of binary gas mixtures. This sensor works based on the permeability change of different gas mixtures across the polymeric membranes. Although high values of permeability and selectivity are needed for an ideal separation, the performance of this sensor mainly depends on the permeability factor. Polysulfone and silicone rubber were applied as the membrane base and coat, respectively. Moreover, in contrast to existing polymeric sensors that use hollow fibers, the present sensor is made of flat membranes. This new design is cheaper, smaller, and easier to use in comparison to the hollow fiber polymeric sensors. In order to test the sensor... 

Production of sand is a common issue in oil and gas fields causing various production problems. However, as a result of sand production, rock permeability can also be increased at near-wellbore areas, which is considered to be an advantage of solid particles production. Therefore, this study aims to investigate sand production behavior and permeability changes during sand production experimentally. To do so, a specific core flooding system capable of applying different radial and axial stresses has been designed which is equipped with a special fluid distributer at the outlet to prevent any sand particle blockage during fluid production. As part of this study, eleven unconsolidated synthetic... 

Enhanced Oil Recovery (EOR) methods have been widely used around the world to improve oil production from petroleum reservoirs. Recently, the injection of the low salinity/smart water has gained popularity among the EOR methods. Different mechanisms are believed to exist during low salinity/smart water injection, including dissolution, precipitation, and ion exchange at the rock surface. In this study, a coupled geochemical-transport model is presented for the detailed analysis and investigation of the interactions between brine, sandstone and carbonate rocks. The proposed model presents the coupling of a geochemical software (PHREEQC) and a species transport model. This coupled method makes... 

Constructing an accurate geological model of the reservoir is a preliminary to make any reliable prediction of a reservoir's performance. Afterward, one needs to simulate the flow to predict the reservoir's dynamic behaviour. This process usually is associated with high computational costs. Therefore, alternative methods such as the percolation approach for rapid estimation of reservoir efficiency are quite desirable. This study tries to address the Well Testing (WT) interpretation of heterogeneous reservoirs, constructed from two extreme permeabilities, 0 and K. In particular, we simulated a drawdown test on typical site percolation mediums, occupied to fraction "p"at a constant rate Q/h,... 

Porosity and permeability alteration due to the thermo-poro-elastic stress field disturbance from the cold fluid injection is a deciding factor for longer, more economic, and safer heat extraction from an enhanced geothermal system (EGS). In the Soultz-sous-Forêts geothermal system, faulted zones are the main flow paths, and the resulting porosity–permeability development over time due to stress reorientation is more sensitive in comparison with the regions without faulted zones. Available operational and field data are combined through a validated numerical simulation model to examine the mechanical impact on the pressure and temperature evolution. Results shows that near the injection...