Abbas Zeinijahromi

Particle Detachment Under Velocity Alternation During Suspension Transport in Porous Media

Flow of suspensions in porous media with particle capture and detachment under alternate flow rates is discussed. The mathematical model contains the maximum retention concentration function of flow velocity that governs the particle release and is used instead of equation for particle detachment kinetics from the classical filtration model. An analytical model for suspension injection with alternate rates was derived, and a coreflood by suspension with alternate rates was carried out. The modelling and laboratory data are in a good agreement, which validates the modified particle detachment model with the maximum retention function.

Mathematical Model for Fines-Migration-Assisted Waterflooding With Induced Formation Damage

Permeability decline during corefloods with varying water composition, especially with low-salinity water, has been widely reported in the literature. This effect can provide a relatively simple method for mobility control during waterflooding. In this work, new basic equations for waterflooding with salinity variations causing the detachment of fine particles, their migration, and their straining are derived. The maximum concentration of attached fine particles as a function of water salinity and saturation is used to model the fines detachment. In large-scale approximation, the equivalence between the model for two-phase flow with fines migration and the adsorption-free polymer-flood model is established, which allows applying a commercial polymer flood simulator for modeling the waterflood with induced fines migration. The modeling showed that the permeability decline in the water-swept zone, caused by the alteration of the injected water composition and induced fines migration, may be able to improve waterflood performance by delaying water breakthrough, increasing sweep efficiency, and reducing the water cut, thus providing a relatively simple method for mobility control during waterflooding.

Size exclusion deep bed filtration: Experimental and modelling uncertainties

A detailed uncertainty analysis associated with carboxyl-modified latex particle capture in glass bead-formed porous media enabled verification of the two theoretical stochastic models for prediction of particle retention due to size exclusion. At the beginning of this analysis it is established that size exclusion is a dominant particle capture mechanism in the present study: calculated significant repulsive Derjaguin-Landau-Verwey-Overbeek potential between latex particles and glass beads is an indication of their mutual repulsion, thus, fulfilling the necessary condition for size exclusion. Applying linear uncertainty propagation method in the form of truncated Taylors series expansion, combined standard uncertainties (CSUs) in normalised suspended particle concentrations are calculated using CSUs in experimentally determined parameters such as: an inlet volumetric flowrate of suspension, particle number in suspensions, particle concentrations in inlet and outlet streams, particle and pore throat size distributions. Weathering of glass beads in high alkaline solutions does not appreciably change particle size distribution, and, therefore, is not considered as an additional contributor to the weighted mean particle radius and corresponded weighted mean standard deviation. Weighted mean particle radius and LogNormal mean pore throat radius are characterised by the highest CSUs among all experimental parameters translating to high CSU in the jamming ratio factor (dimensionless particle size). Normalised suspended particle concentrations calculated via two theoretical models are characterised by higher CSUs than those for experimental data. The model accounting the fraction of inaccessible flow as a function of latex particle radius excellently predicts normalised suspended particle concentrations for the whole range of jamming ratios. The presented uncertainty analysis can be also used for comparison of intra- and inter-laboratory particle size exclusion data.

Skin Due to Fines Mobilization, Migration, and Straining During Steady-State Oil Production

Abstract Permeability decline during core floods with high rates has been widely reported in the literature. It has often been explained by the lifting, migration, and subsequent plugging of pores by fine particles, which has been observed in numerous core flood tests. The phenomena have been connected to well productivity impairment during fines production that also has been widely observed in oilfields. The authors derive a formula for skin factor based on the modified particle detachment model with maximum retention function. The mobilized fines capture by the rock is assumed to be instant at the large reservoir scale, so skin factor drops at the beginning of production and remains constant. The fines migration induced skin is shown to increase with increase of rate and initial attached fines concentration.

Analysis of Low Salinity Waterflooding in Bastrykskoye Field

Low salinity waterflooding is presently one of the most promising enhanced oil recovery (EOR) methods. Wettability alteration and residual oil decrease are the most important EOR mechanisms of low salinity waterflooding. However, the mobility control EOR due to fines migration, induced by low salinity water, and the consequent flux diversion is also an important feature of the smart waterflooding. We analyze the limited available field data from 10 years of low salinity water injection in Bastrykskoye field. The mathematical model for fines-assisted waterflooding is used for history matching resulting in good agreement between the field and modeling data. The model is used to compare recovery factor for two scenarios of low salinity water injection and formation (normal) water injection. Low incremental recovery and low decrease in the amount of produced water during the development of Bastrykskoye field is explained by the production of significant amount of the reservoir water before the commencement of low salinity water injection.

Well Productivity Decline due to Fines Migration and Production: (Analytical model for the regime of strained particles accumulation)

Well index decline has been widely observed for oil, gas and artesian wells producing the reservoir fines. It has often been explained by the lifting, migration and subsequent plugging of pores by fine particles, which have been observed in numerous core flood tests. In this work, the basic equations for the detachment of fine particles, their migration and size exclusion, causing the rock permeability decline, have been derived. The analytical model, developed for the regime of steady state production with gradual accumulation of strained particles, show the linear skin factor growth vs time and vs the amount of produced reservoir fines. Introduction Well productivity decline under fines production is well known phenomenon in low consolidated and high clay contents reservoirs, and also in heavy oil and high rate gas fields (Mungan, N. 1965, Bernard, 1967, Lever and Dawe, 1984, Tiab and Donaldson, 1996, Civan, 2007). It is explained by detachment of the attached particles and clay fines by the drag and lifting forces, exerting the fine particles from the moving fluid; the mobilised fines strain thin pores causing the permeability decline. The reliable prediction of productivity index decline is based on the mathematical modelling. Kinetics of particle capture by the rock from the flowing suspension is described by the filtration equation (Herzig et al., 1970)

Coreflood planning criteria for relative permeability computation by Welge-JBN method

Relative permeability computation is extensively applied in petroleum engineering through the Welge-JBN’s method in unsteady-state corefloods. The purpose of this work is to determine admissible coreflood parameters that could limit the application of the Welge-JBN method. These parameters are presented through theoretical and operational criteria. The theoretical criteria include capillary number and capillary–viscous ratio. The operational criteria consist of measurement precision for pressure, volume sampling for either of phases, water cut measurement precision, and number of samples taken during one pore volume injected. The minimum core length and fluid displacement velocity for specific rock and fluid properties could be determined through these criteria. A laboratory coreflood example was performed using the proposed parameters.

Injectivity formation damage due to fines migration

Formation damage by fines migration during low-salinity water injection can greatly affect field-scale waterflooding projects. In this paper, we present the basic governing equations for single-phase flow with detachment, migration and straining of natural reservoir fines. We perform laboratory corefloods with low-salinity water injections and monitor the breakthrough particle concentration and pressure drop across the core. The analytical model for linear flow matches the laboratory data with high accuracy. The analytical model for radial flow predicts well behaviour from laboratory-tuned coefficients. The calculations show that fines migration during low-salinity water injection causes significant injectivity decline. For typical values of fines-migration model coefficients, injectivity index declines 2–8 times during 10−3 pore volumes injected and the radius of the damaged zone does not exceed a few metres. We present two field cases on waterflooding and low-salinity water injection. The radial model presents good agreement with well injectivity field data.

Low-salinity waterflooding in non-polar oil

Enhanced oil recovery by low-salinity waterflooding is considered to have positive results only when polar components exist in oil. This study shows that low-salinity brine can result in incremental recovery for non-polar oil through fines-assisted waterflooding. Despite the traditional view of fines migration that it should be avoided because of its detrimental effect on reservoir permeability, this work shows that permeability decline is a main mechanism in the low-salinity effect on non-polar oil. Laboratory coreflood tests were performed on a clay-rich Berea outcrop core and a clean sand core to investigate the effect of clay migration when the core is saturated with non-polar oil. The results show that fines migration reduces residual saturation by 18%. In addition, a decrease in the water volume production was observed due to the decrease in water relative permeability.

Evaluation of enhanced oil recovery fromclay-rich sandstone formations

ABSTRACT In the last few years, there has been a growing interest in smart water (SW) flooding as economically and environmentally friendly method to Enhanced Oil Recovery (EOR) in sandstone and carbonated reservoirs. Formation damage especially fines migration and clay swelling by lowering salinity and changing the ionic environment, causes the significant decrease in permeability of the sandstone reservoirs. In this study, an experimental study has been undertaken to illuminate the effect of formation damage during smart water injection as the function of clay types. The state of the art procedure has been established in direction of sandpack construction containing favorable clay content. Injection of smart water was performed in sandpacks with different clay types (montmorillonite and kaolinite). The results show that the presence of montmorillonite augments formation damage and enhances oil recovery. Analyzing Interfacial Tension (IFT) experimental data showed that interaction of oil/SW had no great influence on increasing oil recovery. The results have been achieved based on extensive experiments including Differential Pressure (DP) measurements, Zeta potential, and Recovery Factor (RF). Two mechanisms were proposed to interpret permeability reduction and amount of oil produced values which are clay swelling, and detachment/re-attachment for montmorillonite and kaolinite, respectively.