Crest

A volatile oil contains a relatively large fraction of lighter and intermediate oomponents which vaporise easily. With a small drop in pressure below the bubble point, the relative amount of liquid to gas in the two-phase mixture drops rapidly, as shown in the phase diagram by the wide spacing of the iso-vol lines. At reservoir pressures below the bubble point, gas is released In the reservoir, and Is known as solution gas, since above the bubble point this gas was contained in solution. Some of this liberated gas will flow towards the producing wells, while some will remain in the reservoir and migrate towards the crest of the structure to form a secondary gas cap. 

In order to contain normal or abnormal pressures, a pressure seal must be present. In hydrocarbon reservoirs, there is by definition a seal at the crest of the accumulation, and the potential for abnormal pressure regimes therefore exists. 

Natural gas cap drive may be supplemented by reinjection of produced gas, with the possible addition of make-up gas from an external source. The gas injection well would be located in the crest of the structure, injecting into the existing gas cap. 

In a gas field development, producers are typically positioned at the crest of the reservoir, in order to place the perforations as far away from the rising gas water contact as possible. 

The above descriptions may suggest that rather few wells, placed in the crest of the field are required to develop a gas field. There are various reasons why gas field development requires additional wells ... 

Figure 9.8 Gas cresting in oil rim development with horizontal wells...

Fig. 10. Stream flow over (a) a broad-crested, rectangular weir (b) a cross-current view of the rectangular and CipoUetti weirs (c) a trape2oidal-notch or CipoUetti weir (d) a sharp-crested, triangular, or V-notch weir (e) a cross-current view of the V-notch and hyperboHc-notch weirs and ( a...

R. C. Canfield, R. C. Cox, and D. M. McCarthy, "Monsanto/Lummus Crest Process Produces Lowest Cost Cumene," AlCHE 1988 Spring Meeting, New Orleans, La., Apr. 6—10, 1986. 

Blood Access Devices. An investigational device called the Osteoport system allows repeated access to the vascular system via an iatraosseous iafusion directiy iato the bone marrow. The port is implanted subcutaneously and secured iato a bone, such as the iUac crest. Medications are adrninistered as ia any conventional port, but are taken up by the venous sinusoids ia the marrow cavity, and from there enter the peripheral circulation (8). 

Equation 26 is accurate only when the Hquids rotate at the same angular velocity as the bowl. As the Hquids move radially inward or outward these must be accelerated or decelerated as needed to maintain soHd-body rotation. The radius of the interface, r, is also affected by the radial height of the Hquid crest as it passes over the discharge dams, and these crests must be considered at higher flow rates. 

A two-phase process developed by CDTech in the 1980s (22,23) and Hcensed also by ABB Lummus Crest is claimed to be appHcable to dilute... 

A vapor-phase process primarily for ECC off-gas feeds was developed by Sinopec Technology Company based on a 2eoHte catalyst of the Pentasd type (24,25). It reHes on frequent regeneration of the catalyst to minimi2e pretreatment of the ECC off-gas and allows the impurities in the feed gas to react with ben2ene to form by-products. Consequently, the product yield and purity are low. Joint licensing by ABB Lummus Crest and Sinopec was announced in 1994. 

ABB Lummus Crest Inc. and Unocal Corp. have Hcensed a benzene alkylation process usiag a proprietary zeoHte catalyst. Unlike the Mobil-Badger process, the Unocal-Lummus process is suitable for either ethylbenzene or cumene manufacture (27,28). 

Multiple IJquid-Path Plates. As the Hquid flow rate increases in large diameter crossflow plates (ca 4 m or larger), the crest heads on the overflow weirs and the hydrauHc gradient of the Hquid flowing across the plate become excessive. To obtain improved overall plate performance, multiple Hquid-flow-path plates maybe used, with multiple downcomers. These designs are illustrated and discussed in detail in the Hterature (49). 

For flow over a sharp-crested weir of width b and height L, from a liquid depth H, the flow rate is given approximately by... 

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