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FOREWORD

These recommended practices were prepared by the API Subcommittee on Fracturing Fluid Rheology. These practices and procedures were compiled on the basis of several years of comparative testing, debate, discussion, and continued cross-linked fracturing fluid research in the industry concerning the factors that affect cross-linked fracture fluid behavior.

The recommended practices contained in this document are specifically for mixing and testing cross-linked water-based fracturing fluids. Recommended practices are given for two situations:

a. Laboratory Testing: We have specified procedures for comparative testing and for cross-linked fracturing fluid research and development where the work is conducted in a research laboratory. Data developed for use in hydraulic fracture propagation simulators should be measured using the recommended procedures for laboratory testing.

b. Field Testing: We have also developed procedures for testing cross-linked water-based fracture fluids in the field. These procedures were developed to allow personnel to perform quality control of the base polymer solutions and determination of cross-linked gel properties in field applications to verify the quality of treatment fluids before and during actual fracture treatments. The procedures have been developed only for quality control purposes.

This recommended practice is based on the knowledge and experience of petroleum refiners, valve manufacturers, and others, and its objective is to describe practices that will result in a purchaser's receipt of valves which consistently meet API valve specifications.

Any modifications, deletions, and amplifications necessary for individual users should be made by supplementing this recommended practice rather than by rewriting it.

API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict.

Suggested revisions are invited and should be submitted to the director of the Exploration and Production Department, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.