A new method for injectivity impairment characterization from well and coreflood data

Abstract

The injector impairment due to suspended particles during waterflood project happens in two stages: firstly particles penetrate into a reservoir and are captured by the rock (deep bed filtration); at the second stage, after the reservoir inlet is plugged by particles, the particles build up a filter cake. Prediction of injectivity decline is based on mathematical modelling of deep bed filtration and filter cake formation. The model parameters are determined from either laboratory tests or field data. The model parameters for deep bed filtration - the filtration and formation damage coefficients - can be determined from laboratory pressure measurements using so-called 3-point pressure method. The method for determination of the critical porosity fraction, which is necessary for calculation of the time of transition from deep bed filtration to filter cake buildup, is not available in the literature. In the current paper, the 3-point pressure method was used for determination of the critical porosity fraction. The data from 18 laboratory tests were treated, and the correlation between the formation damage coefficient and the critical porosity fraction was obtained. This correlation allows determining of the deep bed filtration and filter cake buildup parameters from either routine coreflood test or well injectivity history.