Composite slugs

The results show that for a given slug size, a composite slug recovered more crude than a single slug of equivalent size. 

Figure 8. Tertiary Recovery of Bradford Crude Using Oil-Rich, Water-Rich and Composite Slugs...

Single oil-rich Slug water-rich Composite Slug... 

Graded Composite Slugs. In graded micellar slugs, two or more slugs are injected so that a gradation starts with... 

Oil displacement efficiency can be improved considerably when a composite slug is used in place... 

Figure 10. Production History of 5% PV Graded Composite Slug of B4 and 50% PV Buffer Injected at 1.35 m/day...

The amount of processing required in the field depends upon the composition of the gas and the temperature and pressure to which the gas will be exposed during transportation. The process engineer is trying to avoid liquid drop-out during transportation, since this may cause slugging, corrosion and possibly hydrate formation (refer to Section 10.1.3). For dry gases (refer to Section 5.2.2) the produced fluids are... 

Process effectiveness depends on maintaining an ultralow (ca 10 ° N/m (10 dynes/cm)) interfacial tension between the injected surfactant slug and the cmde oil (213). The effect of petroleum composition on oil solubilization by surfactants has been the subject of extensive study (214). 

Analysis of a method of maximizing the usefiilness of smaH pilot units in achieving similitude is described in Reference 67. The pilot unit should be designed to produce fully developed large bubbles or slugs as rapidly as possible above the inlet. UsuaHy, the basic reaction conditions of feed composition, temperature, pressure, and catalyst activity are kept constant. Constant catalyst activity usuaHy requires use of the same particle size distribution and therefore constant minimum fluidization velocity which is usuaHy much less than the superficial gas velocity. Mass transport from the bubble by diffusion may be less than by convective exchange between the bubble and the surrounding emulsion phase. 

As a test, surfactant slug flow experiments were performed in clayey sandpacks with and without the injection of a desorbent behind the micellar slug. Results show that a substantial decrease in surfactant retention is obtained in calcic environment by such an additive. Likewise, the ethoxylated cosurfactant in the micellar slug can be remobilized simultaneously with sulfonatewithout any change in its ethylene oxide distribution. The application of the RST to sulfonate/ ethoxylated alkylphenol mixtures explains semi-quantitatively the relationship between their properties and composition. 

Table VI. Comparison of Tertiary Recovery Using Single and Composite Micellar Slugs...

Example 1 Citrus oil or citrus root products can Indeed kill slugs if they are applied as a contact agent or act as a slug repellent. Although some patents have been issued on the use of citrus oil as a slug control agent, such control with a contact agent is difficult and the chemical compositions of citrus oil and root exudate are ill-defined. Other obstacles for commercialization of citrus oil are (1) market size is too small to justify the development cost, and (2) an effective delivery method has yet to be developed. 

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