# Fracturing Fluids and Their Application in the Republic of Croatia
## 5 Fracturing Fluids--Composition and Additives
### Classification of Fracturing Fluids
#### 5.1.7 Emulsion-Based Fracturing Fluids  
Emulsion-based fracturing fluids include water-oil emulsions, CO\({}_{2}\)-methanol and other types of emulsions (see Table 9). An emulsion is a mixture of two or more liquids that are normally immiscible. Many emulsion-based fluids use emulsions of oil and water and could therefore be classified under oil-based fluids. Emulsion-based fluids reduce or eliminate the use of water. A high-quality emulsion of CO\({}_{2}\) in aqueous alcohol-based gel was used in the western Canadian sedimentary basin as a fracturing fluid in 1981. Since then, the use of such fluids has been very successful, particularly in low-pressure, tight gas applications. The fluids have the same advantages as conventional high-quality CO\({}_{2}\) foams, with the added advantage of minimizing the amount of water introduced into the well [58]. [PERSON] et al. (2010) described a new fracturing fluid obtained with the combination of a single phase microemulsion and a gellable polymer system (SPME-Gel). A microemulsion is defined as a dispersion consisting of oil, surfactant, and aqueous phase, which is a single optically isotropic liquid solution with a droplet diameter usually within the range of 10-100 nm. This formulation was prepared by adding a microemulsion into a gellable polymer system at various concentrations obtaining the characteristics of high viscosity, low fluid loss and low friction. It was also shown that the broken SPME-Gel systems have low residues remaining in the formation, low surface tension, low pressure to initiate cleanup and a high core permeability maintenance, thus offering promising characteristics [59]. A few examples of newly developed synthetic fluids are presented in Table 11, modified according to [23; 24; 25; 60; 61; 62; 63]. \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Fluid Name** & **Fluid Composition** & **Additive Description** & **Purpose of Testing** & **Performed Tests** & **Results** \\ \hline SM-VF & 0.8\% wt supramolecular polymer (SMPT), 0.5\% wt (VESC) (VESC) (VESC) (VESC) & SMPT is synthesized by monomers such as acrylamide, sodium acrylate and ample monomer. Used VES is beating zwitterionic. & Developing very efficient crosslinks in acrylamide, sodium acrylate and ample monomer. Used & The measurement of rheological properties, normal suspension natural assemblies & Fluid is stable at 150 \({}^{\circ}\)C, has better suspension ability than guar-based dust, extremely efficient crosslinking, good cleanup and low formation damage. & Fluid is stable at 150 \({}^{\circ}\)C, has better suspension ability than guar-based dust, extremely efficient crosslinking, good cleanup and low formation damage. & After fracturing, the production of hydrogen suspension natural assemblies & Hydrocarbons is formed with traditional damage. & Hydrocarbons are formed with traditional damage. & Hydrocarbons are formed with traditional damage. & 73 m\({}^{\circ}\)/d oil and \\ Synthetic polymer fluid for ultra-high temperatures & Synthetic polymer as a seedling agent, zirconium as the crosslink, oxidizing breakage and “green” temperature stabilize. & Developing an ultra-high temperature temperature hydraulic fracturing fluid system. & The hydration of gellable agent, measurement of rheological properties, normal suspension natural assemblies & Fluid demonstrates stabilized to 230 \({}^{\circ}\)C, has acceptable fluid loss, and shows controlled breaking with low formation damage. & Hydrocarbons are formed with traditional damage. & Hydrocarbons are formed with traditional damage. & Hydrocarbons are formed with traditional damage. & Hydrocarbons are formed with traditional damage. \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Newly developed synthetic fracturing fluids. In addition to data presented in Table 11, some of the newly developed fracturing fluids are described in more detail.