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This study describes the effects of wormlike micelles formed by the commercial surfactants tallowalkylamidopropyl dimethylamine oxide (Aromox APA‐TW) and oleyl methyl bis(2‐hydroxyethyl) ammonium chloride (Ethoquad O/12) as drag reducers. Ethoquad O/12 is immune to degradation by heat and microorganisms. Conversely, Aromox APA‐TW is biodegradable in the environment, and its susceptibility to heat‐induced degradation was previously assessed. This work considers the effects of temperature, salt, and time on the drag‐reduction capacity (in different Reynolds number) of wormlike micelles of these two surfactants. Wormlike micelles formed by Aromox APA‐TW are able to reduce drag at higher temperatures compared to wormlike micelles formed by Ethoquad O/12. However, Aromox APA‐TW can degrade after being heated to 80 °C and also after storage of the wormlike micelle solutions. Ethoquad O/12 does not undergo degradation after being heated or stored. These surfactants have the potential to be used as additives in industrial operations, as the wormlike micelles formed are able to reduce drag in systems with long pumping distances or recirculation, even in solutions with high salt concentrations (brine) and high temperatures.

The hydraulic fracturing of oil wells is, supposedly, the first technique used to upgrade the oil and gas production. The main idea of this technique is to inject a fluid containing any kind of proppant into the well at a high flow rate and high pressure. One kind of fluid quite used as fracturing material is a cross-linked water-based guar gum gel. It seems that the rheological character of this kind of gel has not yet received the attention it deserves. This material is highly non-Newtonian and must be carefully analysed for further improvement in the fracturing process. We carried out different rheometric tests, which are presented in terms of the shear stress versus shear rate. The material seems to behave like a visco-elastic fluid, reasonably well described by the Jeffrey model. In addition, it is worth noting that the gel is very slippery, even on a rough surface. For this reason, we paid great attention to the maximum stress (a critical stress), above which the gel slips. We strongly believe that this stress has great practical importance for flow assurance and could be used to estimate the total pressure drop in the fracturing process.

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