Modeling of Low Salinity Waterflooding Process in Laboratory Experiments

Optimization of injection water composition during low salinity water flooding in carbonate rocks: A numerical simulation study

The oil recovery from fractured reservoirs is usually low and the early water breakthrough is one result of the fractured reservoir. Two enhanced oil recovery (EOR) methods, low salinity water flooding (LSWF) and micro-gel, have recently drawn great interest from the oil industry. We integrated both methods into one process. The objective of this study was to test how the combining method could reduce production rates from the fractured layer and improve the production rate from the non-fractured layer through laboratory experiments. The parallel non-crossflow models, which were made of sandstone cores and two core holders, were built. The gel strength, water salinity, gel particle size, and sandstone permeability effects on oil recovery, production rate, and gel penetrations were studied. Sodium chloride (NaCl) was used for brine flooding and preparing swollen PPG. Two brine concentrations (1.0, and 0.01 wt. % NaCl) were used for the experiments. A light mineral oil was used. A flow rate of 0.5 ml/min. was used to inject the brine into the parallel non-crossflow models before and after the gel was placed into the fracture. The gel was injected into Outlet 1 to fill out the fracture at a flow rate of 2.0 ml/min until the gel injection pressure reached 500 psi. The optimum water salinity for the application of the coupled method was determined through laboratory experiments to be 0.01 wt. % NaCl because this gave the highest gel penetration into the partially fractured layer. However, the best water shut-off was obtained when the water salinity was 1.0 wt. % NaCl. The incremental oil recovery was almost the same in both 1.0 and 0.01 wt. % NaCl water salinity. When the gel particle size decreased, the water shut-off from the partially- closed fracture layer and the incremental oil recovery from the matrix were increased. This application had no significant effect when the core permeability was low because there was not much of an effect on the production rate ratio after gel treatment. From the laboratory experiments, we concluded that the PPG application might be more successful it is swelled in a low brine concentration.

Summary This paper examines the impact of heterogeneity on Low Salinity Water flooding (LSWF) for a realistic field scale models. We examine various scenarios of permeability variations to cover a wide range of heterogeneity possibilities. Since heterogeneity is known to induce fingering and crossflow effects at the fine scale during conventional water flooding. We analyse these effects where the LSWF process is related to a change in wettability, to determine what should be captured, in terms of solute dispersion, in typical coarse scale simulation models.

Optimizing sepsis care through heuristics methods in process mining: A trajectory analysis

Mechanistic modeling of low salinity water flooding

Improving oil recovery by low salinity waterflooding (LSWF) has gained a lot of attention in the last two decades. The effect of LSWF was demonstrated by coreflooding experiments in several core samples from sandstone and carbonate reservoirs around the world. Also, this effect has been shown at the field scale by some field trails. While the exact mechanisms that cause increased recovery due to LSWF are not fully understood, most agree that changes in wettability and interfacial tension are the reasons that LSWF perform better than high salinity waterflooding (HSWF). Therefore, LSWF can be modeled by changing the property that determines the effect of wettability in fluid flow equations, which is the relative permeability. In this paper, coreflooding results from a carbonate reservoir are used to find the relation between the relative permeability curves for HSWF and LSWF. A numerical simulation model of the coreflooding experiment showed that the relative permeability for the LSWF in carbonate reservoirs can be estimated by changing only one parameter in the Corey-type relative permeability equation of the HSWF: residual oil saturation. An application of this result was performed on a full-field simulation model to evaluate the effect of LSWF using simulation and economics. The field model was built for a carbonate reservoir in the Madison formation of Wyoming. The simulation results showed an increase in the recovery factor of more than 5% by using LSWF instead of HSWF. Furthermore, an economic analysis was performed to determine if the additional oil would justify the expense of making low salinity water. With proper assumptions of the construction and operating costs of a water desalination plant, a development plan with LSWF showed a higher net present value than a development with HSWF. This research provides a practical approach to evaluate the effect of LSWF on certain fields using simulation. It provides a screening tool to evaluate quickly the oil gain from the LSWF before spending money on core samples testing for further research.

Hybrid carbonated low salinity waterflood (CLSWF) introduces synergetic effects of oil viscosity reduction and wettability modification. The technology injecting CO2-saturated low salinity water is a hybrid design of low salinity waterflood (LSWF) and carbonated waterflood (CWF). Coupled with geochemical reaction and equation of state (EOS) modeling, this study proposes compositional simulation of the CLSWF process. In a comparison to LSWF to quantify the synergetic effects, CLSWF introduces enhanced wettability modification effect due to geochemical reactions of ion-exchange and mineral dissolution. The low pH and salinity conditions during CLSWF dissolve significant calcite mineral to increase Ca2+ molality. It results in more cation-exchange and enhances wettability modification following LSWF mechanism. CO2 is transported from CO2-saturated low salinity water to oil during CLSWF. This interphase transport of CO2 reduces oil viscosity improving mobility ratio. As a result, additional oil production with 6% and improved injectivity are observed in CLSWF. In addition, CLSWF introduces CO2 storage effect. Despite of the interphase transport of CO2, significant CO2 is remained in water and captured in reservoir. Therefore, the novel CLSWF is shown to be a promising technology securing both enhanced oil production and CO2 storage.

The authors propose the use of process models for DSS design. The kind of process models suggested are task structures and decision structures with simple graphical syntax and semantics. The process models form the basis for a coherent DSS design methodology, based upon the bounded rationality paradigm. The history of DSS and DSS design is discussed to form a theoretical position. The resulting methodology has been tested and evaluated in a laboratory experiment. The results of this evaluation will be used for continuous improvement of the methodology. >

Availability of sustainable transportation fuels in future hinges on the use of lignocellulosic resources for production of biofuels. The process of biomass pyrolysis can be used to convert solid biomass resources into liquid fuels. In this study, laboratory experiments and process simulations were combined to gain insight into the technical performance of catalytic and thermal pyrolysis processes. Waste pinewood was used as a feedstock for the processes. The pyrolysis took place at 500 °C and employs three different catalysts, in the case of the catalytic processes. A process model was developed with Aspen Plus and a wide range of representative components of bio-oil were used to model the properties of the bio-oil blend. The results of the process model calculations show that catalytic pyrolysis process produces bio-oil of superior quality. Different technical process scenarios were explored based on the properties of the bio-oil after separation of water-soluble components, with the intention of producing a blendable or stand-alone product. It was found that—depending on the bio-oil requirements—sufficient hydrogen can be made available from the aqueous fraction to further treat the organic fraction to the desired extent. The resulting organic fractions are suitable candidates for blending with conventional fuels. The analysis results are used to provide guidance for catalyst development.

The impact of abnormal hours of work on various modes of information processing: a process model on human costs of performance

Many laboratory experiments and field tests have shown improved oil recovery by decrease in injected brine salinity. Spontaneous imbibition experiments provide additional insights into the mechanisms that control low salinity waterflood performance. Most

Effect of different low salinity flooding schemes and the addition of alkali on the performance of low-salinity waterflooding during the recovery of heavy oil from unconsolidated sandstone

Desulfurization technics has been popularly applied to reduce the harmfulness of sulfur dioxide. The reaction characteristics of flue gas desulfurization by magnesia were studied using a lab-scale bubbling apparatus. The effects of concentration of the reagent, flux of the flue gas, concentration of sulfur dioxide, temperature of the absorbent, and bubbling depth on the desulfurization efficiency was investigated with the parameters close to the practice. The experimental results indicate that the desulfurization efficiency is greatly influenced by flue gas flux, sulfur dioxide concentration and bubbling depth. The desulfurization reaction is controlled by the mass transfer of sulfur dioxide from the gas to the reagent solution.

The potential of low salinity water flooding (LSWF) to improve oil recovery in sandstone cores has been well documented. The objective of this paper is further development and examination of a one-dimensional mathematical model for the study of water flooding laboratory experiments. The model describes how dissolution/precipitation of various carbonate minerals and multiple ion-exchange (MIE) will have an impact on the water-oil flow function. The model is formulated such that the total release of divalent cations from the rock surface will give rise to a change of the relative permeability such that more oil is mobilized. The combined effect of MIE and dissolution/precipitation was modelled to determine how this will affect pH and the total release of divalent cations The effects of solubility of carbonate minerals on the ion exchange process during the LSWF have been studied. Dynamic experiments were carried out using brines with different compositions and reservoir rocks. The ion concentrations and pH in effluent samples were determined. In experiments, pH was found to increase during the interaction between low-salinity brine and reservoir rocks. The ion composition of the low salinity brine was also found to change due to interaction with the reservoir rocks. The model developed successfully matched the experimental results. The simulation results show that dissolution of carbonate minerals can occur and this will then alter the composition of the injected low-salinity brine, the concentration of divalent ions on the rock surface and hence the potential of low salinity to improve recovery. It is important during the evaluations of the potential for LSWF to take into account that dissolution of minerals can change the composition of the injected low salinity brine. The potential should be evaluated using the composition that the brine will have in the main part of the reservoir.

Flow dynamics and salt transport in a coastal aquifer driven by a stratified saltwater body: Lab experiment and numerical modeling