Understanding Production Performance & Rock Behavior By Using Different Diversion Techniques in Carbonate Matrix Acidizing Process

Abstract

In stimulated carbonate formations, one damage mechanism is the loss of near wellbore rock compressive strength upon matrix acidizing. Improper designed acidizing jobs may excessively soften the rock and negatively impact the mechanical response of near wellbore rock during production. In this work, an integrated geomechanical workflow is presented and applied to optimize acid placement and fluid diversion treatment in a Middle East carbonate reservoir.

The model consists of petrophysical characterization of the formation, coupled wellbore flow model, rock dissolution model, rock physical model, wellbore stress analysis and lastly production prediction. The model first simulates stimulation fluid movement within wellbore and couples it with transient flow in reservoir. The primary analysis determines the distribution of reactive fluid along the well and predicts porosity evolution across the reservoir domain upon stimulation. Then, the developed geomechanical engine simulates the mechanical behavior (compressional or shear failure) of stimulated rock under different stress conditions during production stage.

This paper introduces an integrated geomechanical workflow to stimulate matrix acidizing and describe dynamic reservoir compaction and its influence on production performance, which varies significantly with the stress condition, formation types and design strategy. In the presented case study, various diversion techniques are analyzed, and overall production are compared to assess the stimulation efficiency by considering the effect of rock failure. The comparative analysis identifies an optimized diversion technique and design, which can minimize near wellbore rock failure and sustain production for a longer term.

This model enables a reliable prediction of acidic fluid distribution and identification of key controlling parameters to maximize conductive reservoir volume and mitigate premature wormhole collapse. Depending on the diversion technique and reservoir conditions, the workflow can provide a proactive solution to improve matrix acidizing design to enhance overall recovery. The presented case study can aid to build a customized and optimized strategy for matrix acidizing for middle east carbonate formations.