Hexion
Winter 2008
 
fracline
 
More Realistic Test Procedures

To more accurately simulate downhole conditions, Hexion™ developed test procedures called the Wet, Hot Crush Test and Cyclic Stress Test. These tests demonstrate how different waterfrac proppants perform under “real-world” conditions.

Crush Cell and Prime Plus Pack Sample

Wet, Hot Crush Test

The standard API RP-56 crush test procedure is run with completely dry samples at ambient temperature, which is very different compared to the conditions met downhole. The API procedure was originally designed for uncoated fracturing sands, not resin coated proppants which require both temperature and stress to bond in the fracture.

Downhole conditions in typical waterfracs subject proppants to elevated temperatures in a wet environment.

In an effort to more closely simulate these conditions Hexion developed the Wet, Hot Crush test. Prior to testing, the sample is exposed to 2% KCl fluid at 200° F for 24 hours under 1,000 psi closure stress. During crushing, the sample is also continuously held at a constant 200° F and the sample is exposed to 2% KCI fluid.

After crushing at temperature, the amount of fines generated are measured after tested material has been dried in a convectional oven.

Cyclic Stress Test

Hexion also developed a Cyclic Stress Test to simulate “real-world” conditions caused by changes in closure stress. Throughout the life of the well, a proppant pack is subjected to numerous stress cycles caused by well interventions and shut-ins. These stress changes can cause the proppant pack to shift, fatigue, and generate increased fines compared to a constant closure stress.

Hexion’s Cyclic Stress Test is run from 3,000 psi to 8,000 psi for a total of three cycles. During crushing, the temperature is held at 200° F and the sample is exposed to 2% KCl solution. Prior to testing, the sample is exposed to 2% KCl fluid at 200° F for 24 hours under 1,000 psi closure stress.

After crushing at temperature, the amount of fines generated are measured after tested material has been dried in a convectional oven.

 
 
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