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Transport and detachment of colloidal particles with irregular shapes occur in geology, environmental, and water-resource engineering. We investigated the effect of shape and aspect ratio on the detachment of non-spherical microparticles attached to a plane substrate, in Couette linear shear flow, under favourable conditions. The detachment conditions were determined by the mechanical equilibrium of drag, lift, gravity and adhesion forces acting on the particle. Drag and lift were evaluated using Computational Fluid Dynamics (CFD), introducing the shape-dependent corrections into traditional formulae for spherical particles. The adhesive particle–surface force is determined by the Surface Element Integration (SEI) method, which also corrects the classical DLVO expression. The forces exerted on spheroids and cylinders can significantly differ from spheres and their detachment exhibit non-monotonic dependencies with aspect ratio. Direct visualisation experiments were performed by piecewise-constant change of flow velocity and the observed detachment were in good agreement with the mechanical-equilibrium based predictions.

Particle capture in porous media and the consequent permeability reduction occur in oilfields during water injection or produced water re-injection, migration of mobilized reservoir fines, and invasion of drilling and completion fluids into formations. Reliable modelling-based prediction of particle propagation in natural reservoirs is an essential step in the planning and design of waterflooding. The mathematical model for suspension-colloidal transport in natural reservoirs contains two empirical functions of retained particle concentration. The filtration function expresses the particle capture rate. The formation-damage function determines the permeability decline due to particle capture and retention. Previous works developed an inverse-problem solution to recover both functions from breakthrough concentration and the pressure drop. The present paper develops a new method that determines the filtration and formation-damage functions from pressure measurements only. The method uses pressure data at an intermediate point of the porous column (core), which supplements pressure measurements at the core inlet and outlet. The proposed method furnishes two retained-concentration functions for filtration and formation-damage. The method is validated by comparison with laboratory experiments. A high fit with the pressure data at three core points was observed. Moreover, the fitted model predicts the pressure measured at other core points with high precision.

Particle detachment during colloidal-suspension transport in porous media occurs in chemical and environmental engineering. Breach of the attached particles mechanical equilibrium conditions yields their mobilisation by rolling, sliding, or lifting. We introduced a novel phase diagram indicating the detachment regime for given transport conditions. The phase diagram structure follows from the mechanical equilibrium conditions. Seven series of laboratory tests in visualisation cell with various parameters have been conducted. Placing the observed detachment parameters on phase diagrams shows that rolling is the dominant detachment regime. A gradual detachment of particles was explained by a probabilistic distribution of the particle and surface parameters, and a novel method for the probabilistic distribution determination is developed. For the laboratory tests performed, correlating the critical velocity for particle mobilisation with asperity size allowed obtaining the asperity distribution on the substrate. The obtained distributions were in agreement with reported values of surface roughness on glass coverslips.

Permeability decline during waterflooding by varying water composition, in particular with low salinity or high pH water, has been observed in numerous laboratory studies. This has been explained by the lifting, migration and subsequent plugging of pores by fine particles. Recently, mathematical models have been presented to investigate the concept of using this permeability decline for mobility control during a waterflood. Now, these models need to be tested against observations during a core flood test. This paper presents a systematic laboratory study to investigate the underlying physics mechanisms for improved oil recovery as a consequence of injecting low-salinity water. Three sister plugs of Berea sandstone were used in the experiments. The first plug was subjected to single-phase waterflood for permeability measurements with varying salinities from 4 (high-salinity) to 0 (low-salinity) g/L NaCl. Core permeability decreased from 495 to 60 md, confirming the effect of changing water composition on permeability. The second plug saturated with high-salinity water was subjected first to primary oil flood (using Soltrol) to the connate water saturation and then to a benchmark waterflood using the same water. The oil recovery was noted and the core was restored to the connate water by a secondary oil flood. Finally, low-salinity waterflood was carried out and oil recovery was recorded. Experimental observations were interpreted using a numerical model. In order to check the reproducibility of the observations, the same experimental procedure was applied on the third plug. Results confirmed the reproducibility of the observations. Significant decrease in water relative permeability by approximately 50% and some decrease in residual oil saturation by about 5% were observed during the low-salinity waterflood in comparison with the high-salinity waterflood. Treatment of the low-salinity coreflood data by a numerical model reveals the decrease in water relative permeability with increasing water saturation at high water saturations. This observation is explained by the expansion of rock surface exposed to low-salinity water during the increase of water saturation. The laboratory data matched by the numerical model shows a high surface exponent value (nA=30), which is explained by a sharp surface area rise at high water saturations. The abnormal behavior of water relative permeability in response to low-salinity waterflood has resulted from matching water permeability increase at low water saturations and decrease at high saturations.

Summary Sulfate scaling in offshore waterflood projects, in which sulfate from the injected seawater (SW) reacts with metals from the formation water (FW), forming salt deposit that reduces permeability and well productivity, is a well known phenomenon. Its reliable prediction is based on mathematical models with well-known parameters. Previous research presents methods for laboratory determination of model coefficients using breakthrough concentration during coreflooding. The concentration measurements are complex and cumbersome, while the pressure measurements are simple and require standard laboratory equipment. In the present work, a new laboratory method is developed for determination of the model coefficients from pressure measurements. Several laboratory corefloods have been performed. The tests show that the proposed method is more precise for artificial cores than for the natural reservoir cores. Further development of the method is required to determine parameters of formation damage caused by sulfate scaling for reservoir core samples.

During reactive flows in porous media with precipitation of a solid chemical reaction product, the permeability reduction occurs. The mathematical model for reactive flow in porous media formulated contains two empirical parameters – the kinetics rate coefficient, determining the reaction rate along with reagent's concentrations, and the formation damage coefficient, reflecting the permeability reduction due to the solid precipitation. These parameters are determined from the laboratory coreflood tests with commingled injection of reacting fluids. A routine laboratory method determines the kinetics rate coefficient from expensive and cumbersome reagent concentration at the core effluent; then, the formation damage coefficient is calculated from inexpensive and simple pressure drop measurements. In the current paper, a laboratory method for determining both coefficients from pressure measurements only is developed. The method utilises pressure measurements at the core inlet, effluent and some intermediate core port during commingled quasi steady state flow of incompatible fluids. The data treatment is based on the analytical model for one-dimensional commingled flow of reacting fluids. The formulae for determining the model coefficients from pressure measurements are derived. The intervals for inverse solution existence, uniqueness and stability are established. Good agreement between the model constants as determined by the routine and three-point-pressure methods validates the proposed method.

Using the law of propagation of uncertainties we show how equipment- and measurement-related uncertainties contribute to the overall combined standard uncertainties (CSU) in filter permeability and in modelling the results for polystyrene latex microspheres filtration through a borosilicate glass filter at various injection velocities. Standard uncertainties in dynamic viscosity and volumetric flowrate of microspheres suspension have the greatest influence on the overall CSU in filter permeability which excellently agrees with results obtained from Monte Carlo simulations. Two model parameters "maximum critical retention concentration" and "minimum injection velocity" and their uncertainties were calculated by fitting two quadratic mathematical models to the experimental data using a weighted least squares approximation. Uncertainty in the internal cake porosity has the highest impact on modelling uncertainties in critical retention concentration. The model with the internal cake porosity reproduces experimental "critical retention concentration vs velocity"-data better than the second model which contains the total electrostatic force whose value and uncertainty have not been reliably calculated due to the lack of experimental dielectric data.

Sulphate scaling with consequent deposit formation and wellbore damage is a well-known phenomenon that occurs during waterflooding, when mixing of incompatible injection and formation waters may result in sulphate salt precipitation and flow restriction. The reliable productivity decline prediction is based on mathematical modelling with well-known model coefficients. The sulphate scaling system contains two governing parameters: the kinetics coefficient characterising the velocity of chemical reaction and the formation damage coefficient showing how the permeability decreases due to salt precipitation.Previous works have derived analytical-model-based method for determination of both coefficients from breakthrough concentration and pressure drop during laboratory coreflood on quasi steady state commingled flow of injected and formation waters, and also from just pressure drop measurements during two corefloods with two different ratios "formation water : seawater".This paper extends the previous works, by sequence of two commingled injections of incompatible waters into the same core with two different ratios "formation water : seawater". Two different slopes of skin factor increase during two injections allow calculating the kinetics and formation damage coefficients in order to predict scaled-up well behaviour.

Mixing of sea- and production waters during waterflooding of offshore oil reservoirs results in reaction of barium and sulphate ions causing precipitation of barium sulphate with consequent rock permeability decrease and well productivity decline. The reliable productivity decline prediction is based on mathematical modelling with well-known model coefficients. The sulphate scaling system contains two governing parameters: the kinetics coefficient characterising the velocity of chemical reaction and the formation damage coefficient showing how the permeability decreases due to salt precipitation.Previous works have derived analytical-model-based method for determination of both coefficients from breakthrough concentration and pressure drop during laboratory coreflood on quasi steady state commingled flow of injected and formation waters. The current study extends the method and derives formulae for calculation of two scale damage coefficients from just pressure drop measurements during two corefloods with two different ratios "formation water: seawater".Data from series of three corefloods on commingled injection with three different "formation water: seawater" ratios, were treated. Equality of scaling damage parameters as obtained from three different floods in similar artificial cores validates the method proposed.