V. C. Santanna

Rheological properties of a new surfactant-based fracturing gel

Surfactant-based fracturing gels are considered as clean gels due to the absence of insoluble residues in their composition. This kind of fluid has been developed to minimize or eliminate damages to fractures. Therefore, new studies about gel rheological properties become more and more important, namely viscosity, the most important property of fracturing gels. This research was accomplished with the purpose of evaluating a new anionic surfactant-based gel. Steady and oscillatory shear experiments were carried out in order to evaluate the inner structure of the developed gel with variable composition, within the gel region in a pseudoternary diagram. It could be observed that small variations in gel composition resulted in changes in micellar structure.

Application of Surfactants for Obtaining Hydraulic Fracturing Gel

Abstract Insoluble residues left in fractures by fracturing fluids have been the object of study by many authors, since these residues cause damage in reservoirs. The objective of this research was the development of a novel surfactant-based fracturing gel with the purpose of minimizing or eliminating the damage in the fracture. A comparison between the properties of a surfactant-based gel and a crosslinked hydroxypropylguar (HPG) fluid was made. Through rheological tests, fluid loss and setting rate, one can conclude that the obtained gel presents compatible characteristics when compared with the HPG gel.

Hydraulic Gel Fracturing

Fracturing gel is a critical component of the hydraulic fracturing treatment. Its main functions are to open the fracture and to transport a propping agent along the length of the fracture. The most common fracturing gels use natural polymers, such as guar, crosslinked by borate to form viscoelastic gels. Due to serious limitations of many polymeric gels, a new generation of fracturing gels based upon viscoelastic surfactants has been developed. This work describes the commonly used fracturing gels.

The Influence of Surfactant Solution Injection in Oil Recovery by Spontaneous Imbibition

Imbibition is the spontaneous displacement of fluids through porous media that occurs until capillary equilibrium is reached. Factors such as wettability and high interfacial tensions may negatively affect the process, requiring additional work to enhance oil recovery. This work aims to explain some aspects of the dynamics of oil recovery by spontaneous imbibition using different fluids. Static imbibition and contact angle experiments were performed using sandstones of the Botucatu Formation (Brazil). The plug samples were exposed to immersion in brine and in surfactant solutions, and the progression of oil recovery was monitored with time. The results showed that the capillary imbibition rate and the oil recovery factor were higher when an ionic surfactant was used. The inverse Bond number and the shape of the recovery profile showed different trends of the capillary imbibition dynamics. Higher oil recovery factors for ionic surfactant were also an effect of the contact angles observed.

The Use of Microemusion Systems in Oil Industry

Microemulsions are thermodynamically stable, isotropic, and macroscopically homogeneous dispersions of two immiscible fluids, generally oil and water, stabilized with surfactant molecules, either alone or mixed with a cosurfactant, as shown in Figure 1 (Robb, 1981). Cosurfactant is a nonionic molecule (e.g. a short-chain of alcohols or amine) that has the function of stabilizing a microemulsified system by decreasing the repulsion forces between the hydrophilic parts of the surfactant.