Low‐salinity surfactant (LSS) flooding is a combined enhanced oil recovery (EOR) technique that increases oil recovery (OR) by altering the rock surface wettability and reducing oil–water interfacial tension (IFT). In this study, optimum concentrations of several types of salt in distilled water were obtained on the basis of IFT experiments for the preparation of low‐salinity water (LSW). Then, a new oil‐based natural surfactant (Gemini surfactant, GS) was combined with LSW to investigate their effects on IFT, wettability, and OR. Experimental results showed that LSW is capable of reducing IFT and contact angle, but the synergy of GS and the active ions Mg2+, Ca2+, and SO42− in LSW was more effective on IFT reduction and wettability alteration. The combination of 1000 ppm MgSO4 and 3000 ppm GS led to a decrease in contact angle from 134.82° to 36.98° (oil‐wet to water‐wet). Based on core flooding tests, LSW injection can increase OR up to 71.46% (for LSW with 1000 ppm MgSO4), while the combination of GS and LSW, as LSS flooding, can improve OR up to 84.23% (for LSS with 1000 ppm MgSO4 and 3000 ppm GS). Therefore GS has great potential to be used as a surfactant for EOR.
Transport of particle suspensions in oil reservoirs is an essential phenomenon in many oil industry processes. Solid and liquid particles dispersed in the drilling fluid (mud) are trapped by the rock (porous medium) and permeability decline takes place during drilling fluid invasion into reservoir resulting in formation damage. The formation damage due to mud filtration is explained by erosion of external filter cake. Nevertheless, the stabilization is observed in core floods, which evidences internal erosion. A new mathematical model for detachment of particles is based on mechanical equilibrium of a particle positioned on the internal cake or matrix surface in the pore space. In the current work the analytical solution obtained for mud filtration with one particle capture mechanism with damage stabilization. The particle torque equilibrium is determined by the dimensionless ratio between the drag and normal forces acting on the particle. The maximum retention function of the dimensionless ratio closes system of governing equations for colloid transport through porous medium.
Oil production is affected by the reservoir pressure, where the higher the reservoir pressure, the higher the production rate. In most cases, water is also produced with oil, which can cause several negative issues. In oil wells, after a short period of oil production, early water production will cause serious decrease in oil production. Actually water coning is an event in which water and oil surfaces will move simultaneously to the well perforation. This event, if occurs in a well, will affect the well production and will increase the costs. Consequently, the production life of the well will be shortened. This paper presents the results of simulation study of an under saturated oil reservoir with no primary gas cap present in the reservoir with oil API gravity of 35. The feasibility of water coning remedy through drilling new horizontal and vertical wells was investigated using ECLIPSE software. The simulation results showed that water production rate is increased with increasing the oil production rate from the reservoir. In addition, water coning was signifi cantly reduced with drilling new horizontal and vertical wells. However, horizontal wells found to be more effective than the vertical wells. The oil production rate increased with horizontal wells while water production rate decreased signifi cantly.
Oil production from reservoirs usually occurs by natural fl ow of the fl uid out of the formation. This oil recovery is called primary recovery, where the production is solely controlled by the natural energy of the formation. However, after some times of production reservoir pressure declines, which causes a decline in oil production rate. Thus, regaining the reservoir pressure to enhance oil production is of great importance. Gas lift as one of the best methods of oil recovery when reservoir pressure declines has been implemented for decades. The reservoir pressure of one of the oil fi elds in Iran has been dropped to a level where no natural fl uid fl ow occurs form the reservoir. Gas lift has been proposed to compensate the natural pressure of the reservoir and ease the petroleum production from the reservoir. PIPESIM software was used to study the effectiveness of the gas lift system. Different parameters including tubing diameter, injected gas rates, and injection depth and their effect on infl ow performance relationship (IPR) were investigated. The simulation results showed that natural energy of the reservoir is not suffi cient for producing oil. Thus, gas lift as of the best methods of increasing the production rate in this fi eld could be implemented successfully.
In the modeling of thermal recovery processes of heavy oil, it is important to know the oil primary relative permeability in the reservoir; moreover we have to be aware of effects of the temperature on oil relative permeability as well.
In this study, a sand pack of quartz (SiO2) has been used to simulate and make a porous medium. Quartz is naturally water wet. During experiments there was no change in the pore volume of the media at different temperatures because of the low expansion coefficient of quartz. The fluid used in experiments is engine oil 50.
Glass pipes with length of 91cm and diameter of 2.6cm have been used in the experiments. At first, columns have been filled with sand, which sand grains had different diameters, then carbon dioxide was injected to the columns to deplete the air in the pores , then the porous media have been saturated with water to calculate the porosity using the scale model. In addition according to Darcys law in steady state, the absolute permeability was calculated.
In the next step, oil was injected to columns until the water saturation reached connate water saturation and finally, water injection was begun to get residual oil saturation (Sor). Experiments results showed that increase of temperature increases the oil relative permeability, note that wetability was constant. Increasing the temperature decreases the oil viscosity then this reduction causes the fluid to move easier and its velocity increases as well.
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