Foamed diversion

Cooke, R.W. Eson, R.L. Field Results of Optimizing the Steam Foam Diversion Process in Cyclic Steam Applications in Proc., SPE International Thermal Operations Symposium, Society of Petroleum Engineers Richardson, TX, 1991, SPE paper 21531. 

Thompson and Gdanski (34) also performed dual-core experiments to determine the best diversion method using foam, and the maximum permeability difference needed to achieve an equal flow rate through the core. Multiple diversion techniques were used, including foamed acid, multiple stages of foamed add, and various qualities of foamed brine. The tests showed that foamed brine reduced flow rates better than foamed add. Also, higher quality foamed brines were most effective. In order to effectively use foamed diversion fluids, the permeabilities of the zones of interest must be relatively similar. The limit on permeability differences is approximately a factor of 10. Otherwise, the more permeable zone will accept both the diversion and treatment fluids. 

The use of foam as a diversion fluid is gaining wider acceptance throughout the petroleum industry. Although foams are not suited for all applications, they are very versatile. The spedfic foamed diversion technique that is used in a treatment design is dependent on individual well characteristics and the stimulation objedive. 

Gdansk , R. and Behenna, R., Design considerations for foam diversion of acid stimulation treatments, in Proceedings, Field Application of Foams for Oil Production Symposium, Olsen, D.K. and Sarathi, P.S., Eds., U.S. Dept, of Energy, Bartlesville, OK, 1993, Paper FS7, pp. 163-172. 

Foam Diversion in Parallel Cores. To assess effectiveness of foams in reducing fluid mobility, coreflood tests are usually conducted in... 

Figure 13. Dual-core apparatus to study foam diversion during acid stimulation.

Coiled tubing is a natural medium for injection of foamed acid or foam diversion. The smaller-diameter coil allows for maintenance of foam quality and stability during injection. This increases the chance of achieving diversion with foam, which is not often efficient or even possible. 

As alternatives to particulate diverters used alone, foam and gel diverters enjoy broad use. Foams do not always work well however, in certain areas, foam diversion is effective. It is useful in gravel pack completions, for example, where particulates do not pass well through the pack or through screen slots. 

Generally, foam is more effective in higher-permeability formations with deeper damage. Furthermore, foam diversion is probably most useful in gas well acidizing. 

Diverter choices are also limited. Ball sealers are usually not effective in horizontal wells, because they tend to the bottom side of the pipe. Foam diversion can be effective, to some extent. In any case, it is known that any attempt to divert acid fluids with a nondamaging diverter is better than no diversion at all. 

Steam-foaming agents that efficiently mobilize heavy cmde oil by heat transfer can reduce the residual oil saturation. This can increase foam stabihty and improve the diversion of subsequently injected steam into oil saturated zones thereby increasing oil recovery (204). 

A mixture of PhenoHc MicrobaUoons and resin binder has a putty-like consistency. It can be molded to shape, troweUed onto surfaces, or pressed into a core. Curing gives a high strength, low density (0.144 g/cm ) foam free of voids and dense areas, and without a brittle skin. Syntactic foams are used in widely diverse appHcations, including boat flotation aids stmctural parts in aircraft, submarines, and missiles stmctural cores for waU panels and ablative heat shields for reentry vehicles and rocket test engines. 

One reason for the success of PVC is its formulation versatility. Products range from rigid piping and window frames to soft flexible foams, with such diverse materials as vinyl leathercloth, flexible sheeting and playballs somewhere in between. 

The market is dominated by flexible foam applications (43% in the United States) and rigid and semi-rigid foam (29%). Cast elastomers (4%) and RIM elastomers (3%) have only specialised outlets. The remaining sizeable 21% of the market cover such diverse uses as thermoplastic rubbers, surface coatings, adhesives, sealants and synthetic leathers. 

The RIM process was originally developed for the car industry for the production of bumpers, front ends, rear ends, fascia panels and instrument housings. At least one mass-produced American car has RIM body panels. For many of these products, however, a number of injection moulding products are competitive, including such diverse materials as polycarbonate/PBT blends and polypropylene/EPDM blends. In the shoe industry the RIM process has been used to make soling materials from semi-flexible polyurethane foams. 

The hydraulic oil must provide adequate lubrication in the diverse operating conditions associated with the components of the various systems. It must function over an extended temperature range and sometimes under boundary conditions. It will be expected to provide a long, trouble-free service life its chemical stability must therefore be high. Its wear-resisting properties must be capable of handling the high loads in hydraulic pumps. Additionally, the oil must protect metal surfaces from corrosion and it must both resist emulsification and rapidly release entrained air that, on circulation, would produce foam. 

Figure 6.2. (a). Colloidal silica network on the surface of spores from Isoetes pantii (quill wort). Scale = 20 pm. (b). Polystyrene networks and foams produced as a biproduct of colloidal latex formation. Both types of colloidal system are typical of the diversity of patterns that can be derived from the interactions of minute particles. Scale (in (a)) = 50pm. 

In the operations of a consulting laboratory, one is constantly confronted with a variety of problems which involve the technology of emulsions and foams. These problems cover a diversity of interests such as foods, cosmetics, adhesives, polymers, and others. 

S. G. Goodyear and P. I. R. Jones. Assessment of foam for deep flow diversion. In Proceedings Volume, volume 2, pages 174-182.8th EAPG Impr Oil Recovery Europe Symp (Vienna, Austria, 5/15-5/17), 1995. 

Food typically is a complicated system with diverse interfaces. Stable air-water or oil-water interfaces are essential for the production of food foams and emulsions. Interface phenomena, therefore, attract great interest in the food industry. AFM provides enough resolution to visualize the interface structures, but it cannot be directly applied on air-liquid or liquid-liquid interfaces. Fortunately, the interface structure can be captured and transferred onto a freshly cleaved mica substrate using Langmuir-Blodgett techniques for AFM scan. Images are normally captured under butanol to reduce adhesion between the probe and the sample. Then, sample distortion or damage can be avoided (Morris et al, 1999). 

It is now well established through studies in many laboratories throughout the world that foam injection shows considerable promise as an agent for the improvement of oil recovery from watered-out. porous media, and for the diversion of the flow of other oil-displacing fluids from more permeable paths into less permeable paths in the medium<1). Whilst the reasons for the effectiveness of foam for these purposes are not. completely clear, the explanation is thought to lie in the behaviour of the foam lamellae... 

The computer age has brought about considerable innovation in the operation of laboratory instrumentation. One consequence of this is the wider acceptance and utilization of the optical microscope as a quantitative analytical instrument. A brief literature survey illustrates the diversity of disciplines and optical methods associated with the development of computer interfaced optical microscopy. This is followed by a description of how our methods of fluorescence, interferometry and stereology, nsed for characterizing polymeric foams, have incorporated computers. 

The typical viscous behavior for many non-Newtonian fluids (e.g., polymeric fluids, flocculated suspensions, colloids, foams, gels) is illustrated by the curves labeled structural in Figs. 3-5 and 3-6. These fluids exhibit Newtonian behavior at very low and very high shear rates, with shear thinning or pseudoplastic behavior at intermediate shear rates. In some materials this can be attributed to a reversible structure or network that forms in the rest or equilibrium state. When the material is sheared, the structure breaks down, resulting in a shear-dependent (shear thinning) behavior. Some real examples of this type of behavior are shown in Fig. 3-7. These show that structural viscosity behavior is exhibited by fluids as diverse as polymer solutions, blood, latex emulsions, and mud (sediment). Equations (i.e., models) that represent this type of behavior are described below. 

In addition to this diversity, a few PVC products, cables or foams for example, are crosslinked. 

The production and properties of ethylene homo- and copolymer foams with densities less than 50 kg/cu.m. are reviewed. A brief historical summary is given, followed by a discussion of six key parameters as they relate to the properties and form of the foam. The diversity of the manufacturing processes available for foam production is illustrated by three distinct operating techniques. Stress-strain curves are used to demonstrate the wide spectrum of properties obtainable and examples of applications are given. 11 refs. 

Diverse foam structure applications In foam rubber, foamed polymers, shaving foams, milk shakes, and whipped creams, slowly draining thin liquid films (TLF) are needed. Accordingly, the rate of drainage is the most important factor in such industrial foam applications. 

Because of the wide diversity in PUF manufacturing processes and likely contaminant chemistry, users are cautioned that sorbent quality control is more critical than with other synthetic polymers such as the Amberlite XAD series. Every effort should be made to procure PUF products consistently from the same manufacturer, preferably in each instance from the same production lot. Moreover, because of inconsistencies in manufacturing practices, first-time foam users should solicit the advice of other satisfied and experienced users in the selection of a sorbent supplier. 

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