Injectivity Decline Under Multiple Particle Capture Mechanisms

Abstract

Severe injectivity decline during seawater injection and produced water re-injection is a serious problem in offshore waterflood projects. The permeability impairment occurs due to capture of particles from injected water by the rock. The reliable modelling-based prediction of injectivity decline is important for the injected-water-treatment design, for injected water management (injection of sea- or produced water, their combinations, water filtering), etc. The classical deep bed filtration model accounts for a single physics mechanism of the particle capture. During laboratory or field data interpretation using this model, it is usually assumed that several simultaneously occuring capture mechanisms are represented in the model by a single overall mechanism. The filtration coefficient as obtained by fitting the model to the laboratory or field data represents the total kinetics of the particle capture. Nevertheless, the kinetics of different capture mechanisms can differ one from another by several orders of magnitude. It highly affects the particle propagation in natural reservoirs and the formation damage. A multiple retention deep bed filtration model describes several simultaneous capture mechanisms. In the present study, a model for deep bed filtration taking into account multiple particle retention mechanisms is discussed. It is proven that the multi capture model can be reduced to a single-capture-mechanism deep bed filtration model. The method for determination of the capture kinetics for all individual capture processes from the breakthrough curve is discussed. As an example, the complete characterisation of filtration with monolayer and multilayer deposition of iron oxide colloids is performed using particle breakthrough curves from coreflooding.