Hexion Specialty Chemicals has developed a new, advanced technology for waterfracs called Prime Plus fracturing proppant.
Prime Plus is a field proven, partially cured resin coated proppant available in a 40/70 mesh size. Designed for use in the waterfrac basins of North America, these proppants are recommended for waterfrac treatments with closure stresses between 6,000 psi to 10,000 psi and bottom hole static temperatures up to 450 degrees Fahrenheit.
Prime Plus provides improved “real-world” fracture flow capacity compared to conventional waterfrac proppants, significantly less fines generation compared to other waterfrac proppants, and partially cured Stress Bond technology which eliminates proppant flowback and wellbore consolidation concerns.
This advanced proppant provides high fracture flow capacity due to its resin coated technology. Prime Plus reduces proppant crushing and fines migration in several distinct ways. The resin coating provides additional strength to individual grains, generates uniform stress distribution throughout the pack, and mitigates fines migration by encapsulating loose fines within the resin coating. Unlike other waterfrac proppants, Prime Plus is partially cured, offering flowback control through Hexion’s Stress Bond (SB) technology, which allows the proppants to bond in the fracture under closure stress.
Prime Plus has been successfully used by an East Texas operator that fracture-treated two similar offsetting Lower Cotton Valley wells; one with Prime Plus 40/70 and one with a tempered resin coated 40/70 proppant. Initial production on the well using Prime Plus proppant was 143% higher and 90-day production was more than 300% higher. The production results showed that the Prime Plus proppant maintained higher fracture flow capacity and provided increased production compared to other proppants.
Hexion has also developed two test procedures to more accurately simulate downhole conditions: the Wet, Hot, Crush Test and the Cyclic Stress Test. These tests more accurately demonstrate how waterfrac proppants perform under “real-world” conditions.
Downhole conditions in typical waterfracs subject proppants to elevated temperatures in a wet environment. The standard API RP-56 crush conditions test procedure is run with completely dry samples at ambient temperature, which is very different when compared to the actual conditions downhole. The API procedure was originally designed for uncoated fracturing sands, not resin coated proppants that require both temperature and stress to bond in the fracture.
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 degrees Fahrenheit for 24 hours under 1,000 psi closure stress. During crushing, the sample is also continuously held at a constant 200 degrees Fahrenheit and the sample is exposed to 2% KCI fluid. After crushing at temperature, the amount of fines generated is measured once the tested material has been dried in a convectional oven.
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.
With Hexion’s Cyclic Stress Test, the sample is exposed to 2% KCl fluid at 200 degrees for 24 hours under 1,000 psi closure stress prior to testing. The sample is then run from 3,000 psi to 8,000 psi for a total of three cycles. During crushing, the temperature is held at 200 degrees and the sample is exposed to a 2% KCl solution. After crushing at temperature, the amount of fines generated is measured once the tested material has been dried in a convectional oven.
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