A differential wide field electromagnetic method and its application in alkaline-surfactant-polymer(ASP) flooding monitoring

To improve effectiveness of ASP flooding, it is necessary to establish a reliable parameter design and tracking adjustment method to monitor the process of oil displacement. A differential wide field electromagnetic method was proposed and applied to the ASP displacement monitoring test in a block of the Daqing Oilfield. In the process of ASP flooding, the electromagnetic field was measured many times. The data acquired before the ASP flooding were set as the background field, and the resistivity model was obtained by inversion. Then, the resistivity data were calibrated by logging data and the resistivity model was established. Finally, the range and front of ASP flooding were deduced with the residual gradient from the spatial domain first-order difference of the resistivity model. Production data of well groups in this block have proved that this method can work out the range and front of ASP flooding accurately, providing support for optimization of ASP flooding parameters.

Treatment of ASP produced water with hydrophilic fibre ball filtration

The conventional treatment process cannot meet the need for treatment of produced water from alka- line/surfactant/polymer flooding（ ASP produced water） in Daqing oilfield. In this study, a new type of hydro- philic fibre ball medium was developed through surface modification method. The hydrophilic property of the surface modified fibre ball was tested with ASP produced liquid at laboratory. The results showed that this fibre hall had higher oll degreasing efficiency, The surface components were also observed by Scanning Electron Microscope and X-ray Photoelectron Spectroscopy, the result showed that the hydrophilic fibre＇ s surface was covered by sulfonic group. Using hydrophilic fibre ball as filter medium, a new type of filter was designed to treat ASP produced water in pilot-scale experiments. The obtained results indicated that this type of filter had high capability and efficiency for the treatment of ASP produced water. This filter should have a better application prospect in oilfield produced water treatment.

Residual oil evolution based on displacement characteristic curve

The purpose of this study was to determine the displacement and dynamic distribution characteristics of the remaining oil in the two development stages of water flooding and subsequent alkaline surfactant polymer(ASP) flooding. The well pattern types in the water and ASP flooding stages are a longdistance determinant well pattern and short-distance five-point well pattern, respectively. The type A displacement characteristic curve can be obtained using the production data, and the slope of the straight-line section of the curve can reflect the displacement strength of the oil displacement agent. A numerical simulation was carried out based on the geological model. The results revealed that the injected water advances steadily with a large-distance determinant water-flooding well pattern. The single-well water production rate increases monotonically during water flooding. There is a significant positive correlation between the cumulative water-oil ratio and the formation parameter. Differential seepage between the oil and water phases is the main factor causing residual oil formation after water flooding, while the residual oil is still relatively concentrated. The effect of the chemical oildisplacement agent on improving the oil-water two-phase seepage flow has distinct stages during ASP flooding. The remaining oil production is extremely sporadic after ASP flooding.

Modeling of kinetic characteristics of alkaline-surfactant-polymer-strengthened foams decay under ultrasonic standing wave

Foaming issues are encountered at the stages in crude oil production, transportation, processing, especially in chemical flooding enhanced oil recovery(EOR) oilfields. These accumulated foams would cause a lot of trouble for downstream operation. The destruction of foams under ultrasonic has been increasingly paying attention in the background of green oilfield development. This study focuses on the decay kinetic characteristics of alkaline-surfactant-polymer-strengthened foams under the ultrasonic standing wave.The performance of the diverse foams was characterized. A decay kinetic model incorporating the energy correlation was developed and validated. The factors that affect the decay kinetic characteristics were discussed. The results indicated that the collapse rate and the collapse volume fraction decreased when the foam size decreased, the gas-liquid ratio decreased and the surface tension increased. Ultrasonic standing wave parameters have a significant impact on the decay behavior of the foam. Both the ultrasonic frequency and ultrasonic amplitude were increased by 50%, the collapse volume fraction of foams increased by about 1.25 times in the identical irradiation time. The relative deviation between the measured results and the model prediction was less than 10%. The potential collapse mechanism was also explained using the principle of energy correlation of foam surface. This study is not only beneficial to provide a robust and rigorous way to defoam of produced liquid in the alkaline/surfactant/polymer(ASP)flooding EOR process but also meaningful to well understand the decay process of oil-based foams.

A review of fluid displacement mechanisms in surfactant-based chemical enhanced oil recovery processes:Analyses of key influencing factors

Surfactant-based oil recovery processes are employed to lower the interfacial tension in immiscible displacement processes,change the wettability of rock to a more water-wet system and emulsify the oil to displace it in subsurface porous media.Furthermore,these phenomena can reduce the capillary pressure and enhance spontaneous imbibition.The key factors affecting such immiscible displacement process are temperature,salinity and p H of the fluids,surfactant concentration and adsorption.Therefore,before any surfactant flooding process is applied,extensive studies of fluid-fluid and rock-fluid interactions are needed.The use of other chemicals along with surfactants in chemical enhanced oil recovery(c EOR)processes have been widely considered to exploit the synergy of individual chemicals and complement the weakness arises from each of them during immiscible displacement of fluids in porous media.Therefore,such combinations of chemicals lead to alkaline-surfactant(AS),surfactantpolymer(SP),alkaline-surfactant-polymer(ASP),and nanoparticle-surfactant(NS)flooding processes,among others.In this review study,we categorised the role and displacement mechanisms of surfactants and discussed the key factors to be considered for analysing the fluid displacement in porous media.

Effect of heterogeneity and injection rates on the recovery of oil from conventional sand packs:A simulation approach

The study of flow through porous media has been of cardinal gravity in oil and gas applications like enhanced oil recovery(EOR),acidizing,fracturing,etc.One of the most anticipated apprehensions is that the core flooding and simulation have become prevalent to understand the flow through porous media.This study aims at simulating and analyzing the effect of alkaline surfactant flooding through heterogeneous permeability conditions in the lab-scale methods.The conventional methods of core flood deal with the effective permeability of the system without considering the effect of heterogeneity within the core.The heterogeneous studies are conducted by simulating a finely meshed 2-D axisymmetric model of the sand pack.The novel Karanj oil surfactant extracted from Pongamia Pinnata,and partially hydrolyzed polyacryl amide polymer are considered for the physicochemical properties of displacing fluid used in the simulations.Different heterogeneity combinations and displacing fluid injection flow rates are introduced for a single absolute permeability system.Results indicate a trend of oil recovery upright with increasing vertical permeability.A lower areal sweep efficiency and early breakthrough are observed in models with high horizontal permeabilities.Further,the effect of heterogeneity on oil recovery is reduced with the increase in injection flow rates of displacing fluid.The present work utilizes computational fluid dynamics to model multiphase flow through a heterogeneous permeability media and its effect on oil recovery.