Table 2 Functions of additives used in fracking fluids (based on[4],[9])
Additive | Function |
|---|---|
Proppants | Keeping the fractures created open under the pressure of the surrounding rock and allows gas/fluid to flow to the well bore |
Scale inhibitors | Preventing deposits of poorly soluble precipitates, such as carbonates and sulphates |
Biocides | Preventing bacterial growth, biofilm formation and formation of hydrogen sulphide by sulphate-reducing bacteria |
Iron control | Preventing iron-oxide precipitation |
Gelling agents | Improving proppant transport |
High-temperature stabilizer (temperature stabilizer) | Preventing gel decomposition at high temperatures within the target horizon |
Breakers | Reducing the viscosity of gel-containing fracking fluids for depositing proppants |
Corrosion inhibitors | Protecting against equipment corrosion |
Solvents | Improving the solubility of additives |
pH regulators and buffers (pH control) | Controlling the pH of tracking fluids |
Crosslinkers | Increasing viscosity at higher temperatures, to improve proppant transport |
Friction reducers | Reducing friction within frac king fluids |
Acids | Pretreating perforated sections of the well, and cleaning them of cement and drilling mud; dissolving acid-soluble minerals |
Foams | Supporting proppant transport |
H2S scavengers | Removing toxic hydrogen sulphide to protect equipment against corrosion |
Surfactants | Reducing surface tension of fluids |
Clay stabilizers | Reducing swelling and migration of clay minerals |