Ft In Depth Research Articles

Seeding of Clouds in Tropical Climates

Warm-cloud seeding with spray or hygroscopic particles often dissipates small clouds but often initiates or increases rainfall from clouds that exceed 4000 ft in depth; seeding with dry ice or silver iodide in supercooled clouds; results of warm-cloud seedings in tropical clouds; new model of convective cloud fields to determine approach of individual clouds to rainstage; effects of warm and of supercooled cloud seeding on this model.

Ocean Wave Forces on Circular Cylindrical Piles

Forces exerted by ocean waves on circular cylindrical piles studied at exposed location near Davenport, Calif, in water from 45 to 50 ft in depth; measurements of forces resulting from waves as high as 20 ft by means of strain gage type force meter; measured forces presented in graphs.

Miscible Drive Field Applications in the Seeligson Field

Introduction Substantial research has been devoted to the possibilities of greatly increasing oil recovery by injecting into reservoirs a gas known to be soluble in the crude. Various requirements, advantages, and disadvantages of such a displacement have been theorized or indicated by laboratory work. In the final analysis, however, extensive field data are required to evaluate satisfactorily the requirements and merits of a recovery mechanism. In this connection an experimental enriched gas-drive pilot project of full reservoir size was initiated in Zone 20-B of the Seeligson field during March, 1957. The Zone 20-B reservoir was selected as an injection project for several reasons. A supply of propane for enriching the gas was available from two gasoline plants in the immediate area. Unitization was not required because the zone has only one operator and one royalty interest. The reservoir has a reasonable configuration, the sand is comparatively uniform, and development is adequate. Another major reason for selecting Zone 20-B is that the saturated crude from this reservoir is similar to substantial reserves in the immediate area so that the data obtained will be useful in the evaluation of other projects. Geologic and Reservoir Data The Seeligson field is located in Jim Wells and Kleberg counties of Southwest Texas. The field is on a large anticlinal structure and contains numerous productive sands varying from 4,500 to 7,500 ft in depth in the Frio and Vicksburg formations. Zone 20-B, the reservoir selected for enriched gas injection, is a sand development lying at a depth of 6,000 ft in the basal portion of the Frio formation. Fig. 1, a cross section through three wells in the field, illustrates Zone 20-B and other sand sections. The reservoir has an average sand thickness of 14 ft and a productive area of 585 acres.

The formation of large droplets in small cumulus

AbstractDroplets of radius exceeding 30 μ are sometimes found in concentrations of order 100/l in non‐precipitating cumulus less than 5,000 ft in depth and having, on average, liquid‐water contents of only a few tenths of a gramme per m3. It is shown that droplets of this size may be produced by condensation and coalescence on hygroscopic nuclei of mass greater than 10−11 g entering the bases of such shallow clouds, provided that these last for at least one hour. The published concentrations of giant salt nuclei seem only just sufficient to account for the observed numbers of large droplets, but simultaneous measurements of both are urgently required.

Ocean Wave Forces on Circular Cylindrical Piles

Forces exerted by ocean waves on circular cylindrical piles studied at exposed location near Davenport, Calif, in water from 45 to 50 ft in depth; measurements of forces resulting from waves as high as 20 ft by means of strain gage type force meter; measured forces presented in graphs.

The Relations between the Bed Medium of Sewage Filters and the Flies Breeding in them

The fauna of sewage filter beds is dominated by certain species of flies and worms, which play an important part in sewage purification processes as they feed on the bacterial, algal and fungal matter which develops in the bed. This growth, if unchecked, would soon block the filter and make it useless for purification. Experience has shown that a filter with large grade medium supplied with a moderate amount of average town sewage builds up a fauna with several successful forms but, under other conditions, the fauna tends to be limited to very few species. It has been suggested that the strength of the sewage is the chief cause of limitation (Lloyd 1945), whilst the method of delivery, the medium used and the way in which the bed is constructed may all have some measure of responsibility (Lloyd, Graham & Reynoldson 1940). On the other hand, it has been held that the loading of the filter is the overriding factor (Tomlinson & Stride 1945). The present studies were made at the Bradford Corporation's works at Esholt and North Bierley. The beds here provide a variety of conditions, both small and large medium with strong sewage and small medium with weak sewage. They were chosen as contrasting with the Knostrop works at Leeds where the medium is large and the sewage relatively weak. The fauna of Knostrop has already been described in detail (Lloyd 1935, 1937). The sewage passing to the Esholt works contains a large proportion of industrial wastes and is characterized by its high biochemical oxygen demand and its low pH. The beds are rectangular in shape, flush with the ground and 6 ft in depth. They are fed from travelling distributors at a rate of 75 gal per sq. yd per day. Hard coal of 3 in. grade is employed as the filtering medium in most of the beds but, in recent years, five acres of this has been replaced by sandstone and river pebbles of 2-21 in. grade. The fungus Fusarium aqueductum (Ascomycetes) is found on both types of medium and is evidently suited to the acid conditions (Butcher 1932). The growth is especially heavy during the winter months when there is a danger of its blocking the filters. There is also a growth of the alga Phormidium (Cyanophyceae) on the pebble beds but not on the coal. In late autumn and winter, this forms a thick leathery growth but

Reduction in Permeability With Overburden Pressure

Oil bearing rocks, usually found at depths of 2,000 to 10,000'Ft, areelastically deformed by overburden pressure. Although the change in porositywith pressure in a number of example rocks has been shown to be small, it wasthought that overburden pressure might have a significant effect onpermeability. This note presents results of an investigation to determine themagnitude of the change in permeability with pressure. In routine core analysis, permeabilities are measured on rock samples whichare not under overburden pressure. If permeability measured in this way differsfrom permeabilities measured under overburden pressure, a systematic error isintroduced into well productivity calculations. The experiments described inthis report were made to determine the magnitude of the change and thus to givean estimate of the error introduced into the calculations. The error introducedby the neglect of the change in permeability when overburden pressure isremoved may account for part of the difference between well productivitycalculated from core analysis and the actual well productivity. The results obtained in this investigation have only qualitativesignificance because of the difficulty in reproducing in the laboratory thestress conditions on the rock buried in the earth. The assumption which isusually made is that the rocks in the earth are under a uniform pressure equalto the weight per unit area of the vertical overburden column from the rock inquestion to the surface of the earth less the pressure of the liquid in thepores of the rock. For an overburden consisting of sandstones and shales (ofassumed average specific gravity of 2.3) and for a liquid pressure equal to thepressure in a salt water column (of specific gravity 1.0) reaching from therock to the surface, the resulting net pressure on the rock is approximately0.56 psi per ft of depth. Experimental Method Clean, dry sandstone core plugs one in. in diameter and about three in. longwere mounted in a copper foil jacket as shown in Fig. 3 or molded in a Lucitejacket as shown in Fig. 4. All cores except those labeled "2" in Fig. 1and "8" in Fig. 2 were measured in the copper foil jacket. Cores"2" and "8" were measured' in the Lucite jacket. T.N. 147