A Method to Predict the Injectivity Decline Rate in Water Injection Wells: Chihuido de la Sierra Negra Oilfield. A Case to Study

Abstract

Chihuido de la Sierra Negra oilfield is the most important one in Argentina. It is located in Neuquen province .It produces 24,000 oil m3/day from 683 producing wells, and it has been working with secondary recovery since 1994. At present 76,000 m3 of water are injected daily into 545 injection wells.A method based on the results gotten from core lineal flooding tests is used to predict the injectivity decline rate produced by solids suspended in produced water.The flood tests were carried out by injecting waters containing different concentrations of suspended solids in order to feature the particle deposition mechanism at middle porosity. Unlike previous studies, this method uses Scanning Electron Microscopy (SEM), which leads to the appraisal of the depth and extent of the core invasion to characterize the kind of filter cake formed.. The impairment mechanism observed is compared to prediction based on the relation between the particle diameter median and the pore throat diameter median.The experimental parameters obtained from core filtration data are used in mathematic expressions of published models to build the half-life time curve from different concentrations of suspended solids.The results obtained allowed us to estimate how the water can be treated, and/or state the filtration degree required so as to get the minimum treatment cost that can keep injection in progress and thus assuring the highest production.This approach also avoids frequent oversizing practices in the design of surface facilities.

A New Comprehensive Approach for Predicting Injectivity Decline during Waterflooding

“…The heterogeneity (layer structure) and the compressibility of the filter cake are neglected. The consideration of these factors requires a more sophisticated model for the external cake (Cavallaro and Baigorria, 2000). It is beyond the scope of the current work.…”

“…Prediction and simulation of the processes are of great importance for the water management and the well stimulation strategies Bedrikovetsky et al, 2009;Cavallaro and Baigorria, 2000;Pang and Sharma, 1997). There is a considerable and ongoing effort aimed at understanding the complicated mechanisms causing the formation damage and the measures to minimize it.…”