Formation damage due to colloidally induced fines migration

Abstract

The in-situ release of fine particles in a porous medium resulting from changes in the colloidal character of fines induced by changes in the electrolytic condition of the permeating fluid and its effects on processes related to enhanced oil recovery (EOR) are examined. Experimental results show that high pH and low salinity cause fines to be released which, in turn, causes a drastic decline in the permeability of the medium. These results and other key experiments establish the interplay between salinity changes, cation exchange, and pH during a water shock, and elucidate the vital role of the ion-exchange process in formation damage. A physico-chemical model based on the fundamental principles of ion exchange and colloidal chemistry shows qualitative agreement with experimental observations. The results of this study will find use in various areas such as: bacteria migration in soils, failure of earthen embankments, and contaminant transport during ground water flow.

Migrations of Fines in Porous Media

“…Predictions of CSC based on the approach developed by (Khilar and Fogler, 1984) and (Mohan, 1996b) give excellent qualitative and reasonable quantitative agreements with measurements (Khilar et aI., 1990;Vaidya and Fogler, 1990;Khilar and Fogler, 1984;Kia et aI., 1987a;Kia et aI., 1987b;Mohan, 1996b). From the Table 3.1.2, we observe for Berea sandstone, the CSC ofNaCl, CsCI and CaCh are 0.07 M, 0.006 M and less than 0.0001 M respectively.…”

A Model System to Study the Precipitation and Migration of Colloidal Particles in Porous Media

“…The conditions for release and subsequent migration of fines relates to the interaction forces between the particles and the matrix of the pore space. For clays in sandstone at intermediate pH values, for instance, migration occurs for low electrolyte concentration, when electrostatic repulsive forces between the negatively charged particles and the negatively charged quartziferous surface predominate over the van der Waals attraction and the particles become free to be carried by the fluid (25). Similar conclusions have been inferred from results obtained for other systems (26).…”

Navajo Sandstone–brine–CO2 interaction: implications for geological carbon sequestration

“…Dissolution steps are visible along the c-axis of the cleavages and dissolution channels along the b-axis of the cleavages; h SEM microphotograph shows the surface morphology of a K-feldspar particle after reaction; i enlarged view of an area outlined by the black box in h, showing an etch pit and Fogler 1990). This phenomenon is called ''water sensitivity'' and the resulting decrease in hydraulic conductivity is called ''formation damage'' (Baudracco 1990;Khilar and Fogler 1984;Khilar et al 1983;Kia et al 1987;Mohan et al 1999;Ochi and Vernoux 1998;Vaidya and Fogler 1990). During geological carbon sequestration, the injection of CO 2 may cause abrupt changes in solution chemistry (pH decrease and carbonation), possibly resulting in the detachment of clay coatings.…”

“…may modify the balance between the forces at the particle-grain interface and result in particle detachment (Cerda 1987;Khilar and Fogler 1998;Kretzschmar et al 1999;Vaidya Intensive dissolution features (e.g., etch pits on K-feldspar); clay minerals (e.g., flaky illite/ smectite); illitization of smectite; no carbonate minerals observed The overall analytical error for dissolved species is ±5% a In situ pH is calculated from distribution of aqueous species calculations at the temperature and pressure of the experiment using constraints imposed by major element concentrations and pH values measured at 25°C The overall analytical error for concentration measurements is ±5% Fig. 5 a SEM microphotograph shows secondary minerals on a quartz surface after Experiment #2.…”