Non-Guar Synthetic Hydraulic Fracturing Gels – Successful Concept of Choice

Abstract

Fluids capable of transporting proppant with the least formation and fractures contamination are one of the most relevant areas of the technological development of hydraulic fracturing treatment. In the world in recent years, there has been a tendency to switch from cross-linked guar-based fracturing fluids to synthetic ones. Highly viscous friction reducers find wider application in the new concept of modern industry development. Unlike traditional guar-borate-based fluids, these fluids have a number of advantages - they provide higher residual fracture conductivity, are less sensitive to the mineral composition and temperature of the water source, contain fewer chemical elements in the working formulation and, as a rule, are less demanding of equipping a hydraulic fracturing fleet. Also, in addition to the above features, note the possibility of making changes to an engineering solution immediately in the work process, ensured by the simplicity of fluid making-up and high hydration rate. Despite the obvious advantages in using synthetic fluid systems over standard guar-based systems, until now they have not been widely used in conventional reservoirs. This is supported by poor knowledge of the practical application associated with proppant transport and the absence of selection criteria based on the system rheological properties which significantly affect the hydraulic fracturing success rate. The paper describes a set of rheological studies, including building viscosity and elasticity profiles, as well as an assessment of the fluid system thermal stability. The viscosity behavior was also studied in a wide range of shear rates. The effects of elastic moduli were studied by conducting vibrational-shear tests in a spectrum of various frequencies. Quantitative and qualitative comparative measurements were carried out to study the settling rate of proppant, as well as its viscoelastic properties in a flow. The result of the study is generalized analytical findings on synthetic fluid systems confirmed by practical application in real conditions of conventional reservoirs in West Siberia. This paper will help to understand the key factors affecting the choice of fracturing fluid formulations based on high-viscosity friction reducers and, in the future, may become the basis for creating a methodology for testing synthetic gels.