Ion Exchange Between Hydrogen and Homoionic Brines Related to Permeability Reduction

Abstract

Formation damage due to clay migration may be observed when the injected brine replaces the connate water during operations such as waterflooding, chemical flooding including alkaline, surfactant and polymer processes. This work deals with the effects of physico-chemical changes induced by brine replacement on the permeability behavior of consolidated argillaceous sandstones. The experimental investigation is made up of:-core flow experiments in clayey sandstones. Effluent pH and ionic concentration are measured at the outlet of the porous medium and permeability variations are simultaneously monitored when the injected salinity is abruptly decreased.-batch coagulation tests giving both critical salt concentration and pH in a salinity-pH diagram. Brines are prepared with sodium and potassium salts. A physico-chemical flow model is also developped based on cationic exchange with the proton when the salinity decreases. The model allows: -the interpretation of the experimental observations (pH and concentration)-the knowledge of the transition compositions -the effect of the major parameters like the clay content through the cation exchange capacity. The model gives pH and salinity profiles. The comparison of these values with the salinity-pH diagram critical ones leads to the prediction of the effect of the fluid composition on the damage process.

Evidence, mechanisms and improved understanding of controlled salinity waterflooding part 1: Sandstones

“…RezaeiDoust et al (2011) reported modest increases in oil recovery when injecting higher salinity NaCl brine into a core containing crude oil and CaCl2 brine, and argued that this reflected the differing affinities of Na + and Ca 2+ cations toward clay mineral surfaces, consistent with the model predictions. Ion exchange leading to pH increase has been observed and modelled in other studies relating to formation damage, although these studies considered only monovalent ions in single phase flow (e.g Vaidya and Fogler, 1990;Souto and Bazin, 1993…”

Effect of Brine Composition and Alkaline Fluid on the Permeability Damage of Limestone Reservoirs

“…Jones 1 reported the capabilities of small proportions of divalent cations, such as calcium and magnesium, for controlling clay blocking. Souto et al 4 dealed with the effects physico-chemical changes induced by brine replacement on the permeability behaviour of consolidated argillaceous sandstones. Clays having sufficient adsorbed calcium and magnesium resisted dispersion by water and consequent blocking of permeability.…”

“…In Figure 6, from the concentration profiles of NaOH at the effluent, 40 000 ppm brine + 0.6 % NaOH concentration curve shows that the front of the solution was stable. Figures 12 and 13 show the changes in permeability reduction with injected volume of NaOH and NaSiO 4 . The distilled water + 0.4 % NaOH alkaline solution gave less oil recovery while the others gave incremental oil recovery when compared with the base flood.…”

Modeling Chemical EOR Processes: Some Illustrations from Lab to Reservoir Scale

“…Alkali, polymer and surfactant species adsorptions are Langmuir-like [17,18]. More sophisticated is the case of the surfactant, where the Langmuir plateau is a product function of the water salinity (say chloride and sodium ions concentrations) and pH (say hydroxide ions concentration), in order to take into account the alkali effect on limiting the surfactant adsorption:…”