Crush resistance is one of the defining properties of any frac proppant. Under closure stress inside a fracture, the proppant must keep its conductivity by not generating excess fines. For Vaca Muerta horizontals, where TVDs commonly range from 2,500 m to 3,500 m, the stress loads on proppant pack are material. Silica sand is the standard for this depth range when used in appropriate stress classes.
Per API Recommended Practice 19C, crush resistance is quantified by applying progressively higher confining stress to a sand sample in a crush cell and measuring the percentage of fines generated. The result maps to a stress class (e.g. 4K, 6K, 8K psi). Each stress class has a maximum fines percentage threshold.
Typical Vaca Muerta hydraulic fracturing stages see closure stresses in the 5,000–8,000 psi range depending on TVD, landing zone and frac design. Silica sand proppants are routinely deployed across this envelope, often blended or supported by higher-strength proppant in the most stressed intervals.
| Stress class | API 19C max fines | Vaca Muerta applicability |
|---|---|---|
| 4K (4,000 psi) | Per API table | Shallow intervals |
| 6K (6,000 psi) | Per API table | Mid-depth unconventional |
| 8K (8,000 psi) | Per API table | Deeper liquids-rich and gas |
Exact fines thresholds per API RP 19C Tables. The In-Basin Sand crush class is validated through the SGS Minerals (Chile) attrition report and available under NDA.
A proppant pack that generates excess fines under closure stress loses conductivity and reduces long-term well productivity. The choice of crush class is one of the most impactful specs in a frac design, linked directly to decline rates and ultimate recovery. Matching the stress class to the depth of the landing zone is standard industry practice.
The Malargüe silica used by In-Basin Sand has been characterised under the SGS Minerals (Chile) attrition and granulometry test program. The report covers crush response, particle size distribution and turbidity. It is available in the data room under NDA.
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