Application of a New Class of Surfactants in Stimulation Treatments

Abstract

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractDifferent acid systems have been used to stimulate production and injection wells for more than a century. Several chemicals are added to the acid to enhance the efficiency of the acidizing treatments, including various types of surfactants.Surfactants play a key role in many well treatments because of their unique properties. Surfactants are used to reduce surface tension, change wettability, mobilize residual oil, and disperse corrosion inhibitors. They are also used as anti-sludge agents, emulsifiers in acid-oil emulsions, and demulsifiers. This wide spectrum of applications is due to the ability of surfactants to adsorb on various surfaces and associate in the bulk of solutions and form micellar structures. The properties of surfactants depend on the size of the head, tail length, and configuration of the tail, surface charges, ionic strength and temperature.Recent advances in surfactant technology have introduced a new class of surfactants with special characteristics useful in oilfield applications. This new class of surfactant has the ability to form viscoelastic systems, which can be used to increase viscosity of the treating fluids, without causing formation damage. These surfactants have been used in Saudi Arabian fields to enhance diversion during matrix acid stimulation, reduce leak-off during acid fracturing and to minimize losses (well control) during workover. The system proved successful to provide fracture extensions in acid fracturing applications of low temperature seawater injectors and high temperature gas wells. These surfactant systems are non-damaging and do not require sized solids to control losses, which eliminates the need for remedial acid treatments.

Effect of Salts, Alkali, and Temperature on the Properties of Sodium Oleate Hydrogel

“…The molecular weight of surfactant molecules is usually less than 1000, and they consist of a hydrophilic head and a long hydrophobic tail . The physical nature of the surfactant depends on its tail length, branching of the tail, number of double bonds, and cis/trans configuration . The surfactant molecules are like monomers, and the volume ratio of the surfactant tail group to the headgroup is defined as the micelle packing ratio.…”

pH-Responsive Anionic Wormlike Micelle Based on Sodium Oleate Induced by NaCl

“…This highly entangled structure results in solution phase change, and thus contributes to form a solution with great viscoelasticity. Hitherto, the fascinating properties of the WLMs render them extremely useful in many aspects of industrial applications including oil production, 5,6 drag reduction agent, 7,8 and drug delivery. 9,10 Recently, reversible WLMs have attracted considerable interest due to their remarkable superiorities whose viscoelasticity can be readily controlled via common stimuli, such as pH, 11−13 CO 2 , 14,15 light, 16,17 and temperature.…”

Development of a Stimuli‐Responsive Gemini Zwitterionic Viscoelastic Surfactant for Self‐Diverting Acid

“…In the very beginning, cationic quaternary ammonium surfactants were employed to be the thickeners of self‐diverting acids and clean fracturing fluids, but adsorption of cationic surfactants to negatively charged reservoir minerals may result in an adverse influence on the permeability. Furthermore, cationic surfactants have poor salt and heat tolerance because of the stronger chemical interactions by the positively charged head group (Nasr‐El‐Din et al, ; Zhao and LÜ, ). Thus, most of the viscoelastic surfactants applied in the acidizing matrix were zwitterionic surfactants that simultaneously contain positive and negative charge.…”