Abstract
The American Petroleum Institute (API) crush tests for proppants found in recommended practices (e.g. RP 56, 58, & 60) are typically used to compare the crush resistance of recognized API proppant sizes at a predetermined stress under dry and ambient conditions (API, 1995). This procedure has remained the same through several API committees since the early 1980s without change. More recently, the International Organization for Standardization, ISO 13503-2, reviewed the procedure and made only slight changes, most notably in the time for which the stress is to be applied (ISO, 2006). The "new" procedure from ISO gives no indication of how the stress changes the overall mesh distribution. It also sheds no light on how key factors such as moisture, temperature, time, or cyclic loading change performance characteristics. This work addresses these issues.
The down-hole environment where the proppants are placed is wet, hot, and pressurized. Incorporating these variables into a modified API test procedure for crush resistance better represents actual down-hole conditions to which a proppant is subjected. This information is critical in establishing required propped fracture conductivity, and thus, proppant selection.
In this study a standard API crush cell was modified for pressurized fluid flow at temperature and used to quantify the effects of the parameters described as compared to standard API crush tests. Tests were performed on the following proppants: light weight ceramic (LWC), intermediate density ceramic (IDC), and high strength bauxite (HSB).
Modified testing exposes critical proppant failures under conditions that more closely simulate those experienced downhole; these failures are not be revealed by current standard API/ISO test procedures. The modified procedure results in an improved method for better understanding downhole proppant pack performance.
