Introducing New API/ISO Procedures for Proppant Testing

Abstract

Abstract In 2001, the International Organization for Standardization (ISO) and American Petroleum Institute (API) formed a new committee to write procedures for measuring the properties of proppants used in hydraulic fracturing. API Recommended Practices (RP) for testing of proppants are generally "reviewed and revised, reaffirmed, or withdrawn at least every five years" in accordance to API instructions. The last Recommended Practice was published in December 1995. The committee was charged with re-writing API RP 56, 58, and 60 relating to sand as a proppant, gravel packing, and high strength proppants, respectively. This new document, ISO 13503-2 "Measurement of Properties of Proppants Used in Hydraulic Fracturing and Gravel-Packing Operations" is a standard. Any company may follow these procedures and state on their published data that they followed ISO procedures to generate the specifications of their product. Several changes have been made to the Recommended Practices, and the goal of this paper will be to highlight these changes, and to discuss the potential impact on the proppant industry. In 2003 a second committee was formed to write procedures on measuring long term conductivity of a proppant pack. The industry was using for years a procedure based on API RP 61 "Recommended Practices for Evaluating Short Term Proppant Pack Conductivity" 1989, which is an obsolete document. Roughly a dozen facilities worldwide are running long term conductivity tests, all slightly different. Recent advances in technology have been incorporated in this standard to increase the accuracy of the results, and to standardize the equipment and testing procedures. The new standard is ISO 13503-5 "Procedures for Measuring the Long-Term Conductivity of Proppants". These two new procedures will enable users to evaluate and to compare proppant characteristics under the specifically described test conditions for use in hydraulic fracturing operations. They are not designed to provide absolute values of proppant conductivity under downhole reservoir conditions. Test data has shown that time, elevated temperatures, fracturing fluid residues, cyclic stress loading, embedment, formation fines, and other factors will further reduce proppant pack conductivity.