Coupled Adsorption/Precipitation Of Scale Inhibitors: Experimental Results And Modelling

Abstract

In this paper, results are presented on the general mechanisms by which scale inhibitors (SIs) are retained within porous media. There is a generally accepted view that the main two mechanisms of SI retention are "adsorption" and "precipitation" and these are described by different but related modelling approaches in the literature. These approaches have been used quite successfully to model field squeeze treatments. To analyse in a detailed and unambiguous manner where a given retention mechanism (e.g. pure adsorption) or mechanisms (e.g. coupled adsorption and precipitation) are operating requires that we carry out careful laboratory experiments under "field relevant" conditions.In this work, we study adsorption vs. adsorption/ precipitation by performing a series of experiments where we know that the system exhibits either (a) adsorption only or (b) coupled adsorption/precipitation. Experimentally it is straightforward to determine which regime the system is in, as explained below. We present the theory describing the coupled adsorption/precipitation process. In addition, an extensive series of experimental adsorption/precipitation measurements are presented for various mineral separates including sand, chlorite, siderite, muscovite, kaolinite, feldspar and montmorillonite. The coupled adsorption/ precipitation model is in very good agreement with experiment.

Chemical Inhibitor Adsorption and Desorption Characteristics of Common Gravel Pack Sands Under Static and Dynamic Conditions

“…Langmuir adsorption isotherms are the most widely used models for obtaining adsorption and desorption models for a range of adsorbate-adsorbent systems (Kahrwad et al, 2008;Patroni Zavala et al, 2008). The static and dynamic tests' results are therefore presented in form of adsorption and desorption rate profiles and fitted Freundlich and Langmuir models.…”

“…The most common preventative approach to scale and corrosion mitigation uses chemical inhibitors squeeze treatment. Chemical inhibitor squeeze treatment involves dissolution of a chemical inhibitor in a carrier fluid and ‗forceful' injection of the fluid stock into the producing formation rock through the production well in a staged process that includes pre-flush, main treatment, over-flush and well shut-in (Kerver, 1965;Kahrwad, 2008). The injected inhibitor adsorbs on the surface of the formation rock during the injection with substantial adsorption taking place during shut-in.…”

“…The injected inhibitor adsorbs on the surface of the formation rock during the injection with substantial adsorption taking place during shut-in. The adsorbed inhibitor then desorbs into the produced formation water streams as the well is opened and put back on production, inhibiting scale formation by delaying mineral crystal nucleation and retarding crystal growth (Van Rosmalen, 1983;Kahrwad, 2008). This process is made possible by the attachment of the inhibitor molecules to active growth and nucleation sites of scale crystals (Patroni Zavala et al, 2008) Evaluation and qualification of chemical inhibitors prior to field application is a common practice in the oil and gas industry.…”

Effect of Produced Sand Particles and Fines on Scale Inhibitor: A Review

“…These studies have focused only on the evaluation behavior, performance, and interaction of scale inhibitor chemicals in relation to scales mitigation efficiency within porous media. Squeeze treatment designed for steady injection of inhibitor is also published [22].…”

Effect of Produced Sand Particles and Fines on Scale Inhibitor: A Review

“…While a squeeze treatment is designed to provide a steady release of inhibitor, which has been retained in the formation (Kahrwad et al, 2009), the precise retention mechanism and performance of the inhibitors in sand producing reservoir is a subject of concern that requires concerted research.…”