Soap-Oil Systems For Formation Fracturing

Abstract

Abstract One of the important characteristics of a fluid is its viscosity, since this is closely associated with its sand-carrying ability. From the standpoint of economy it is sometimes more advantageous to thicken a non-viscous petroleum fluid, than to use a more expensive, naturally viscous oil. This paper discusses the use of certain alkali metal, oil-soluble soaps in. non-polar solvents, such as kerosene, diesel fuel, and crude oil. By in situ neutralization of long chain aliphatic organic acids, in a hydrocarbon media, a sodium-soap dispersion is obtained. Such soaps produce micelles, the aggregation of which results in low fluid loss and low sand-falling rates. Also, the fluid exhibits thixotropic properties, providing additional sand support without a corresponding increase in the true or Newtonian viscosity. This paper describes the characteristics of the micellular aggregations, their formation and properties. The relationship between the apparent and true viscosities of such dispersions is shown. The effect of brine on these soap-oil systems is also discussed. Introduction Oil-dispersible alkali metal soaps have been familiar industrial compounds for several years; they have found many uses in various fields. Because of their unique colloidal nature in nonaqueous solvents, their use has been recently extended to formation fracturing for primary recovery of well fluids. This paper will discuss some of the aspects and properties of certain alkali metal oil-soluble soaps in non-polar solvents such as kerosene, diesel fuel, and crude oil. Many improvements have been made in materials and techniques of application, since the introduction of hydraulic fracturing as a method of stimulating production from oil and gas wells. A variety of fluids have been employed to open fractures and carry propping agents, among which are gels, emulsions, and refined oils. Developments made during the last few years have included modifications of these fluids in order to overcome and eliminate certain difficulties that were encountered in field applications. The most recent general development in fracturing fluids has been a soap-oil dispersion that combines the best features of other fracturing fluids and overcomes many of their disadvantages. The familiar phenomenon of mice the formation of soaps in aqueous solutions also occurs in nonaqueous media. This was demonstrated by Reuggerberg and other workers in this field. By in situ neutralization of long chain aliphatic organic acids in hydrocarbons, a sodium soap dispersion can be obtained that is a satisfactory fluid for fracturing.