Emulsion fracturing

Blauer, R.E., Phillips, A.M., and Craig, D.P. "Rheological and Physical Differences Between Foam and Emulsion Fracturing Fluids," SPE paper 18214, 1988 SPE Annual Technical Conference and Exhibition, Houston, October 2 5. 

Nasr-el-din, H.A., Surfactant Use in Acid Stimulation in Surfactants, Fundamentals and Applications in the Petroleum Industry, Schramm, L.L. (Ed.), Cambridge University Press, Cambridge, UK, 2000, pp. 329-364. Sinclair, A.R. Terry, W.M. Kiel, O.M. Polymer Emulsion Fracturing in Proc., Annual Technical Conference of SPE Society of Petroleum Engineers Richardson, TX, 1973, paper SPE 4675. 

Sinclair, A.R., Terry, W.M., and Kiel, O.M. (1973) Polymer emulsion fracturing. Proceeding of the Annual Technical Conference of SPE, Society of Petroleum Engineers Richardson, TX, paper SPE 4675. 

Emulsion drilUng fluids emulsion fracturing, stimulation, acidizing fluids enhanced oil recovery (EOR) in situ emulsions produced (well-head) emulsions bituminous oil sand process and froth emulsions heavy oil pipeUne emulsions fuel oil and tanker emulsions... 

Emulsified fracturing fluids are typically very viscous polymer oil-inwater emulsions that may consist of60-70% hquid hydrocarbon dispersed in 30-40% aqueous solution or gel. The hydrocarbon phase may be diesel fuel, kerosene, or even crude oils and condensates. The aqueous phase may consist of gelled fresh water, a KCl solution or an acid solution. Emulsion fracturing fluids may be applied to oil or gas wells, particularly in low pressure formations susceptible to water blockage, and for bottom-hole temperatures of up to about 150 °C. They can provide excellent fluid loss control, possess good transport properties and can be less damaging to the reservoir than other fluids. However, emulsions are more difficult to prepare and can be more expensive. 

If the viscous bitumen in a tar sand formation can be made mobile by an admixture of either a hydrocarbon diluent or an emulsifying fluid, a relatively low temperature secondary recovery process is possible (emulsion steam drive). If the formation is impermeable, communication problems exist between injection and production weUs. However, it is possible to apply a solution or dilution process along a narrow fracture plane between injection and production weUs. 

Alkanolamine Chelates. Alkanolamine chelates, which are prepared by reaction of tetraalkyl titanates with one or more alkanolamines, are used primarily in cross-linking water-soluble polymers (qv) (see Alkanolamines) (104). The products are used in thixotropic paint emulsion paints, in hydrauhc fracturing and drilling of oil and gas wells, and in many other fields. The stmcture of... 

Fracturing fluids are often classified into water-based fluids, oil-based fluids, alcohol-based fluids, emulsion fluids, and foam-based fluids. 

The majority of hydraulic fracturing treatments are performed using water-based fluids foams (with nitrogen or carbon dioxide as the gas phase) have been used extensively in recent years to reduce formation damage. Oil-external emulsions have also been used for... 

Fluid loss additives are used are used to reduce the rate of fluid loss from the fracture to the formation and to naturally occurring macro- and micro-fractures within the formation. Silica flour (73,74), oil-soluble resins (75), diesel oil emulsions (5% by volume) (74) have also been used. 

Acids can sometimes break emulsions within the formation either by reducing the pH or by dissolving fine particles which can stabilize emulsions. Breaking the emulsion reduces fluid viscosity thus increases the fluid carrying capacity of the flow channel. Acids may be used as breakers to reduce the viscosity of acid-sensitive fracturing gels. 

Acids were an early exception to the no water rule. It was recognized that aqueous solutions of acids would inhibit swelling of clays and shales as well as dissolve any acid-soluble minerals contained in a formation. By 1933 commercial well stimulation with hydrochloric acid was of great interest. A whole separate methodology and treatment chemistry has since evolved around acidizing and fracture acidizing(54). Water emulsions, mainly emulsified acids, and gelled acids thickened with polymeric additives were applied early in the history of well treatment. 

Emulsions. Emulsion fluids and foams came into routine use in competition with crosslinked fluids during 1970-80. Simple, barely stable emulsions had been used early in fracturing. These were mainly emulsified acids that "broke" when the acid spent on the formation surfaces. In the late 1960 s Kiel became a proponent of very high viscosity oil fluids as a method to place exceptional (at the time) amounts of proppant(337,338). To avoid the frictional resistance typical of gelled oils he advanced the concept of preparing a very viscous oil-external emulsion with one part fresh water, 0.1% sodium tallate surfactant, and two parts oil. The viscous emulsion had to be pumped simultaneously with a water stream to minimize frictional pressure. This process was clumsy and still... 

Roodhart, L.P. Davies, D.R. "Polymer Emulsion The Revival of a Fracturing Fluid , SPE/DOE paper 16413, 1987 SPE/DOE Low Permeability Reservoirs Symposium, Denver, May 18-19. 

Kiel, O.M. "Method of Fracturing Subterranean Formations Using Oil-In-Water Emulsions," US Patent 3,710,865(1973). 

Krishan, K., Kapoor, S., and Goyal, K.L. "Development of Polymer Emulsion as Fracturing Fluid," Chemical Abstracts 103(20) 162915z(1985). 

Graham, J.W., Gruesbeck, C., and Salathiel, W.M. "Fracturing Subterranean Formations Using Oil-in-Water Emulsions," US Patent 3,977,472(1976). 

Bernard, P.J. "Neutral Cationic Emulsion Containing a Slow-Fracturing Hydrocarbon Binder," Chemical Abstracts. 78(12) 74596f (1973). 

Kiel, O.M. "Hydraulic Fracturing of a Subterranean Formation with a Viscous Oil-In-Water Emulsion," US Patent 3,552,494(1971). 

Siegele, F.H. "Oil Well Fracturing Wax Emulsion Fluid Loss Additive," US Patent 3,477,512(1969). 

Oilfield drilling fluids, organic titanium compounds in, 25 133 Oilfield emulsions, colloid, 7 274t Oilfield hydraulic fracturing fluids, organic titanium compounds in, 25 133 Oil fields, lithium in, 15 124 Oil-field waters, lithium-bearing, 15 128 Oil filters, phenolic resins in, 18 790 Oil-furnace blacks, 4 762 manufacture, 4 780—785 Oil gas, 6 787... 

FIG. 11. Transmission electron micrographs of freeze fractured oily droplets dispersed (a) in a hexagonal and (b) in a cubic liquid crystalline phase, bar 100 nm. From Mueller-Goymann, C., Liquid crystals in emulsions, creams and gels, containing ethoxylated sterols as surfactant, Pharm. Res. 1 154-158 (1984). 

Finally, an important feature of gels made of adhesive emulsions arises from the deformation of the droplets. Indeed, as the temperature is lowered the contact angles between the droplets increase [27,28] (see Chapter 2, Section 2.3). Consequently, the structure of the final floes depends on the time evolution of the strength of the adhesion. Initially, the adhesion results in the formation of a random, solid gel network in the emulsion. Further increase of adhesion causes massive fracturing of the gel, disrupting the rigidity of the structure and leading to well separated, and more compact floes [27,28]. 

Studies on the kinetics of carbon black dispersion in various rubbers have been reported using a Brabender mixer fitted with cam-type rotors [110]. Dispersion rating, determined by visual inspection of photomicrographs, was found to depend strongly on mixing time. For an SBR emulsion, it was observed that there was an initial delay period where the carbon black agglomerates were thought to be fractured and incorporated into the rubber. Subsequently, the process of dispersion continued for a considerable time thereafter. 

Various electron microscopy techniques have been used to study the structures of whippable emulsions such as normal and cryo-scanning electron microscopy or transmission electron microscopy using various preparation methods such as freeze fracturing, freeze etching, etc. The literature is quite extensive, and only a few important papers will be discussed in this chapter. 

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