The effectiveness of clay stabilizers in the prevention of formation damage has typically been evaluated by simple filtration tests or simple slurry settling tests. Unfortunately, not only do these tests lack sophistication, they are often performed with off-the-shelf mineral standards like silica and bentonite because actual reservoir rock is not available. Furthermore, brine has been observed to mitigate formation damage as well as any clay control chemistry in these tests. Based on these results, is the use of a stabilizer even necessary?
Instead of relying on simple tests using bentonite, actual reservoir rock should be tested with more advanced methods such as the following:
- Roller Oven Stability: demonstrates core stability and fines migration.
- Nano-Indentation: measures change in rock mechanics on the shale surface which shows the potential for rock to soften when exposed to untreated water.
- Proppant Embedment: measures change in fracture face surface properties and loss of frac width as proppant is embedded.
Conventional clay control chemistries are no longer relevant with shales, produced brine waters are being used with increasing frequency, and new chemistries that prevent damage are now available. The more test types (such as those above) that can be run, the more confidence you will have in your clay control additive selection and the advantages it can provide to shale reservoir rock!