Abstract

A new technical standard is developed to measure rheology of completion fracturing fluids. This method details step-by-step procedure for making fluids and rheology measurements. Completion fluids are defined for the purpose of this technical standard as viscosified treating fluids used during the completion or workover of a petroleum or natural gas producing well. The objective of this technical standard is to provide a standard procedure for measuring the viscous properties of single-phase, non-particulate-laden completion fluids. These fluids are viscosified brines, gravel pack carrier fluids, and fracturing fluids. These fluids can be either crosslinked or non-crosslinked (aqueous, hydrocarbon, or acid based). An optional shear history simulation procedure is provided for fluids that are potentially shear-sensitive. This procedure is designed to simulate the shearing effects experienced by a fluid in surface apparatus and during the time it is being conveyed down the wellbore.

Introduction

Completion fluids are defined for the purpose of this document as viscosified treating fluids used during the completion or workover of a petroleum or natural gas producing well. The objective of this document, which is based on the ISO 13503–1 is to provide a standard procedure for measuring the viscous properties of single-phase, non-particulate-laden completion fluids[1]. These fluids are viscosified brines, gravel pack carrier fluids, and fracturing fluids. These fluids can be either crosslinked or non-crosslinked (aqueous, hydrocarbon, or acid based).

An optional shear history simulation procedure is provided for fluids that are potentially shear-sensitive. This procedure is designed to simulate the shearing effects experienced by a fluid in surface apparatus and during the time it is being conveyed down the wellbore. Shear history simulation is most often used during the development of new fracturing fluids to characterize their sensitivity to shear.

This document presents a standard procedure for measuring the viscosity of completion fluids.

Fluid Preparation
No Shear History

Certain aspects of sample preparation and handling may affect the viscosity or rheological properties of a fluid. During all procedures, steps shall be taken to minimize entraining air into the fluid. Following preparation, all fluids, except those intended to be used as fracturing fluids, shall be filtered through a 2 µm filter. Minimize the entrainment of air during the filtration process.

The procedure used to prepare the fluid sample shall be documented as follows:

  1. Description and/or composition of the base fluid. Preparation of the fluid shall be described, starting with the fluid source, such as deionized water, tap water, seawater (location), or type of oil;

  2. Identification of mixing apparatus, container volume, and total volume of fluid prepared;

  3. Identification of each fluid component and amount added;

  4. The order and method of addition of each component;

  5. Mixing speeds with time at each speed;

  6. Ageing or holding time prior to measurements, if required;

  7. Temperature (required only for fracturing fluids);

  8. pH (for aqueous fluids, where applicable);

  9. All other aspects of the fluid preparation which are known to affect the outcome of the viscosity measurement should be reported.

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