Mobilization of Fine Particles during Flooding of Sandstones and Possible Relations to Enhanced Oil Recovery

Abstract

The mounting evidence that waterflooding of clay-containing sandstone reservoirs using floodwater with reduced salinity can enhance oil recovery, but with unpredictably large variation in responses, demands improved understanding of the underlying mechanisms. Mobilization of clays and other fines is one candidate mechanism. Flow experiments in Berea sandstone plugs were designed such that the change in their fines distribution from before to after the oil and water injections could be imaged in exactly the same pores using scanning electron microscopy. This technique also allowed imaging of the wettability distribution on pore surfaces and was coupled to spectroscopic analysis of the adsorbed asphaltene amounts. One-phase flows switching from highto low-salinity water led to only a low level of fines mobilization, compared to two-phase experiments in which high-or low-salinity water displaced crude oil from mixed-wet prepared plugs. The images reveal that loosely bound, partially oil-wet fines lining sandstone grains are stripped by the adhering oil during its recovery and redeposited on grains further downstream. Reduced salinity increases the fraction of fines thus mobilized by weakening their bonds to grains and strengthening their bonds to oil. Evidence suggests that these more oil-wet fines stabilize the water-in-oil curved menisci, which can aid in maintaining the connectivity of the oil phase and thus enhance oil recovery.

Characterization of reactive flow-induced evolution of carbonate rocks using digital core analysis- part 1: Assessment of pore-scale mineral dissolution and deposition

“…Similar findings related to mobilization of fine particles observed from the µ-CT and SEM images have been reported by others (Noiriel et al, 2005;Lebedeva et al, 2009;Kumar et al, 2010;Fogden et al, 2011). More M A N U S C R I P T ACCEPTED MANUSCRIPT 23 interestingly, Garing et al (2015) and Mangane et al (2013) clearly showed areas within the samples where pores were filled by solid particles after the experiments.…”

Quantifying the Transport of Superparamagnetic Nanoparticles in Porous Media Using an Acrylic Flow Cell and Integrated Magnetic Susceptibility Sensor Technique

“…The ability to monitor fines migration simultaneously during a fluid flow experiment would complement the recent interesting work by Fogden et al (2011) and Kumar et al (2011) on the mobilization of fine particles during fluid flooding. They compared scanning electron microscopy (SEM) images of cut faces of core plugs before and after flooding experiments to demonstrate mobilization of fine particles within identical small areas.…”

Induced migration of fines during waterflooding in communicating layer-cake reservoirs

“…probably needs further refinement in the future work (see experimental evidence from Fogden et al (2011)). With this modification, the expression of the erosion number in Eq.…”

“…Injection of low salinity water into a saturated core of high salinity has been observed to give rise to significant reduction of permeability owing to the migration and the recapture of clay fines (Fauré et al, 1997;Fogden et al, 2011;Lever and Dawe, 1987;Mohan et al, 1993;Ryan and Gschwend, 1994;Sharma and Yortsos, 1987). There exists a critical salt concentration (CSC) below which the clay particles start to release.…”