Page 343 - Reservoir Formation Damage

Chapter 13

Inorganic Scaling

and Gepchemical
Formation Damage

Summary

Various processes leading to inorganic scaling and formation damage
are discussed. Special attention is given to formation damage caused
by the adverse reactions encountered during acid stimulation, brine
incompatibility in seawater injection for water flooding, precipitation
caused by CO 2 and light hydrocarbon gases near wellbore, and sulfur
deposition. The alterations of thermodynamic and chemical balances
in favor of precipitation, precipitate aggregation, crystal growth, and
inorganic scale formation are discussed and mathematically formulated.
The rate processes governing the cation exchange, adsorption/desorption, and
dissolution/precipitation reactions are formulated. The criteria for precipitate
forming conditions are derived. Typical applications to above mentioned
inorganic precipitation and scale formation processes are presented.

Introduction
Inorganic scaling is a process of deposition of scales from aqueous
solutions of minerals, referred to as brines, when they become super-
saturated as a result of the alteration of the state of their thermodynamic
and chemical equilibria (Amaefule et al., 1988). Inorganic scaling can
occur in the well tubings and near well bore formations of the production
and injection wells.
Amaefule et al. (1988) explain that conditions leading to supersaturation
can be created by various mechanisms at different stages of reservoir
exploitation. Scaling is caused essentially by mixing incompatible fluids
during well development operations, such as drilling, completion, work-
over, such as acidizing. Scaling is caused by a decrease of pressure and

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