Matrix acidizing is one of the few well interventions where a few hours of engineering decides whether the next decade of production lives up to forecast. This guide collects the workflow KEMISIM engineers use across sandstone and carbonate wells in the Middle East, Asia and Africa — from candidate screening through post-job evaluation.
1. Candidate selection: skin, not age
The most reliable predictor of acidizing uplift is not well age or cumulative production — it is the magnitude and mechanism of skin. Pressure-transient data, PI decline analysis and offset analogues triangulate whether the damage is near-wellbore (treatable) or completion- and reservoir-driven (not treatable).
- Confirm skin from build-up or step-rate, not nodal alone.
- Diagnose damage mechanism: fines, scale, organic, drilling-mud.
- Check producibility envelope — high water cut wells need different design.
2. Sandstone vs carbonate: different physics, different fluids
Sandstone acidizing is mineral chemistry: HF reacts with aluminosilicates and silica, HCl with carbonate cement and iron compounds. The risk is secondary precipitation and fines mobilization. See the deep-dive on sandstone acidizing fluid selection for HF/HCl ratio decisions by mineral assemblage.
Carbonate acidizing is transport-limited: HCl dissolves the matrix into wormholes whose efficiency depends strongly on injection rate, fluid viscosity, temperature and heterogeneity. The wormhole propagation article explains the optimal-rate curve in practice.
3. Diversion is half the job
On any interval more than ~30 ft, coverage decides the outcome. Chemical diverters, viscoelastic surfactants, foam and mechanical isolation each have a place. See acid diversion strategies for long, layered and deviated wells for the decision framework.
4. Pumping schedule: physics, then operations
A defensible pumping schedule is built from reactive-transport simulation under realistic well constraints — surface pressure limits, rate envelopes, and the diversion sequence. Diagnostic stops let the crew confirm in real time that the design is tracking.
5. Post-job evaluation closes the loop
Real pressure response and post-job skin tell you whether the model was right. Matching that response refines every future treatment on the field — and is the cheapest engineering you'll ever do.
Tooling
KEMISIM's matrix acidizing software implements this workflow end-to-end with reactive transport, wormhole propagation, multi-stage diversion design and a post-job skin tracker.