Spill point

Combustion behavior differed in some respects between continuous and instantaneous spills, and also between LNG and refrigerated liquid propane. For continuous spills, a short period of premixed burning occurred immediately after ignition. This was characterized by a weakly luminous flame, and was followed by combustion of the fuel-rich portions of the plume, which burned with a rather low, bright yellow flame. Hame height increased markedly as soon as the fire burned back to the liquid pool at the spill point, and assumed the tilted, cylindrical shape that is characteristic of a pool fire. 

Similar behavior was observed for LNG clouds during both continuous and instantaneous tests, but average flame speeds were lower the maximum speed observed in any of the tests was 10 m/s. Following premixed combustion, the flame burned through the fuel-rich portion of the cloud. This stage of combustion was more evident for continuous spills, where the rate of flame propagation, particularly for LNG spills, was very low. In one of the continuous LNG tests, a wind speed of only 4.5 m/s was sufficient to hold the flame stationary at a point some 65 m from the spill point for almost 1 minute the spill rate was then reduced. 

Eocene a significant oil column and gas cap were established, at least in the upper units of the Brent Group. The main pulse of oil charging occurred in the Oligocene and Miocene, with maximum oil filling (to spill point) in the latest Miocene. Later (Pliocene-present) the oil-water contact moved up (10-15 m) owing to gas leakage and pressure increase. Pre-production oil-water contact was at 2710 m relative to mean sea level (MSL) (2600 m relative to sea floor) over most of the field. 

Petroleum may not remain in the first trap it encounters and spillage can occur the most dense fluids can be displaced past the spill point if less dense fluids, especially gas, continue to reach the trap. This process of displacement—tertiary migration — can significantly affect the composition of hydrocarbons encountered in a sequence of stacked reservoirs, possibly leading to the presence of oil in the most shallow units and gas in the deeper units. 

The vertical interval from the crest of the reservoir to the petrolenm water contact is termed the pay zone. Not ah of this interval may be prodnctive. It may also contain impermeable strata. Thns it is nsnal to differentiate between the gross pay and the net effective pay. The vertical interval from the crest of a reservoir to the lowest closing contour on a trap is termed the closnre. The lowest closing contonr is termed the spill plane. The nadir of the spiU plane is termed the spill point. Depending onthe amount of petroleum available a trap may or may not be full to the spill point. The term field is applied to a petroleum-productive area. An oil field may contain several separate pools. Apool is a petroleum accumulation with a single petroleum-water contact. 

Assuming that the evaporation rate coefficient, is constant over the entire length of the slick, a streamwise variation in the concentrations of compounds within the slick can be caused in only two ways. First, a variation in slick composition could be caused by spilling a mixture of compounds into one end of a slick while compounds rapidly and selectively evaporate and dissolve from the slick. In such a case, the composition of Ae slick near the spilling point would resemble the composition of the spilled product, while the portions of the slick farther downstream from the spilling point could contain less of the more volatile compounds. Second, a variation in slick composition may be caused by variations in the aqueous concentration of a compound beneath the slick. If toe aqueous concentration beneath the slick varies significantly from one end of the slick to the other, the dissolution rate, which is driven by the difference between the actual water concentration and the equilibrium concentration in the water, would also vary from one end of the slick to the other. Over time, the variation in dissolution rate could create a variation in slick composition. 

As in the Burro Series, the release point was instmmented to measure the instantaneous rate of LNG discharge from the 25-cm diameter insulated release line. Release rates varied from 6 m /min to 19 m /min, with total volumes spilled from 3 m to 28 m. Downwind instmmentation was organized into arrays at different distances of 110 up to 500 m downwind from the spill point and located on towers to accommodate multiple levels of... 

Bivane anemometers were installed to measure atinospheric lurbulence at heights of 1.36, 3, and 8 m at two locations (62 m upwind of the spill point and 300 m downwind of the spill point). These data were not provided by LLNL to WRI for the DOE HSC database. 

Heat flux sensors to measure heat flow between the ground and the dispersing cloud were located on the desert surface at locations in the downwind arrays. Type K thermocouples were positioned on the downwind array towers to measure cloud temperature as it moved downwind. Multiple levels of thermocouples were located just upwind of the spill point, as well as four resistive temperature devices (RTD), one defined as Ihe absoluie temperature (0.5-m height) and three to provide delta temperature measurements relative to the absolute reading (1, 2, and 4 m). 

Because of the experience gained in the Burro Series experiments, the downwind gas concentration sensor arrays were modified. This was based on the facts that beyond 400 m from the spill point the very low concentrations made the sensors of limited value and that close to the spill point, water and mud thrown up by RPT explosions had adverse effects on the sensors. Most of the open-path IR sensors for the measurement of LNG concentration were positioned at multiple levels on the downwind arrays between 140 and 400 m. In addition, some alternative sensors from International Sensor Technology and Mine Safety Appliance for measuring concentration were installed. 

Because of the objective to observe vapor cloud fires during some of the releases, sensors were installed to measure flame velocity during these vapor cloud fires. Four calorimeters manufactured by Hy-Cal Engineering were installed at four downwind stations at a height of 1 m. Twenty-seven LLNL-developed flame-velocity sensors were deployed at nine towers downwind of the spill point at three different levels. 

Wind held measurements were made using two-axis cup-and-vane anemometers located at 11 stations and positioned 2 m above the ground. These were positioned both upwind and downwind from the release point. Fifty m upwind of the spill point were four levels of 1,000 O platinum RTD mounted in aspirated solar shields. Bivane anemometers were installed to measure atmospheric turbulence at three heights at two locations (50 m upwind of the spill point and 100 m downwind of the spiU point). The bivane data were not provided by LLNL to WRI for the DOE HSC database but are provided as plots in the Desert Tortoise Data Report (Goldwire et al., 1985). 

The downwind instrumentation grid of multiple levels of sensors was defined by two arrays, a mass flux array at 100 m and dispersion array at 800 m downwind from the spill point. Up to eight additional portable ground-level stations were fielded in fwo disfanl arcs at distances of 1,400 or 2,800 m and, on occasion, at 5,500 m downwind. 

These experiments used the new tank farm, which contained two 26,000-gallon cryogenic storage tanks that were connected to the spill point with 500-ft-long spill pipes which were comprised of two 12-in. insulated lines and one 6-in. insulated line (which was not used in these experiments). Each spill pipe was equipped with a control valve at each end. 

During Tests 3, 4, 5, and 6, additional atmospheric water vapor was provided to study the effects of increased relative humidity on the resulting eloud. This was attempted using two different methods. First, a steam boiler and water injeetion system was loeated upwind of the spill point. The injection system consisted of an array of spray nozzles, half for steam and half for warm water located approximately 25 m upwind of the release point. The spray system was 22 m long and was located approximately 3 m above the ground. The nozzles were oriented horizontally and pointed upwind from the spill point. The second technique involved a shallow pond, 250 m X 600 m, which was constructed upwind of the spill point. 

Concentration measurements of HF downwind of the spill point were made at three arrays located 300, 1,000, and 3,000 m downwind from the spill point. The centerline of the array... 

Spill points, formed where material could spill from a conveyor, which could be guarded by. side rails and netting on overhead conveyors... 

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