Deposit permeability

The main transporter for these migration forms is subsurface water. That is why their mobility is determined by physical and chemical properties of water, gradient of the hydrostatic head, rock and deposit permeability. Aquaphiles migration direction, rate and distance is determined by hydrodynamics and noticeably depend on their depth. With depth, migration rates of both water and its components decline. 

The deposit permeability can also be calculated using the Carman-Kozeny equation, when particle shape and deposit porosity are known ... 

Keywords reservoir structures, faults, folds, depositional environments, diagenesis, geological controls, porosity, permeability... 

SWS are useful to obtain direct indications of hydrocarbons (under UV light) and to differentiate between oil and gas. The technique is applied extensively to sample microfossils and pollen for stratigraphic analysis (age dating, correlation, depositional environment). Qualitative inspection of porosity is possible, but very often the sampling process results in a severe crushing of the sample thus obscuring the true porosity and permeability. 

If appropriate, correlation panels may contain additional information such as depositional environments, porosities and permeabilities, saturations, lithological descriptions and indications of which intervals have been cored. 

Collapse Breccia Pipe Deposits. The primary occurrence of coUapse breccia pipe deposits is in circular, vertical pipes fiUed with down-dropped fragments. Uranium is concentrated in the permeable breccia matrix and in the accurate fracture zones enclosing the pipe. An example of... 

Precipitate formation can occur upon contact of iajection water ions and counterions ia formation fluids. Soflds initially preseat ia the iajectioa fluid, bacterial corrosioa products, and corrosion products from metal surfaces ia the iajectioa system can all reduce near-weUbore permeability. Injectivity may also be reduced by bacterial slime that can grow on polymer deposits left ia the wellbore and adjacent rock. Strong oxidising agents such as hydrogen peroxide, sodium perborate, and occasionally sodium hypochlorite can be used to remove these bacterial deposits (16—18). 

Toxicity. The toxicity of barium compounds depends on solubility (47—49). The free ion is readily absorbed from the lung and gastrointestinal tract. The mammalian intestinal mucosa is highly permeable to Ba " ions and is involved in the rapid flow of soluble barium salts into the blood. Barium is also deposited in the muscles where it remains for the first 30 h and then is slowly removed from the site (50). Very Httle is retained by the fiver, kidneys, or spleen and practically none by the brain, heart, and hair. 

There are some solids, however, which form a less permeable cake, even in veiy thin layers. With these sohds, the resistance of the deposited cake will be veiy high when compared to that of the precoat bed, and the slope of the filtrate cui ve will be -t-0.5 for all v ues of form time. 

Note that the air rate at the beginning of each drying or dewatering period within a given cycle starts at zero and then increases with time. The shape of this cni ve will be a function of the permeability of the deposited cake. 

The most harmful deposits are those that are water permeable. Truly water-impermeable material is protective, since without water contacting metal surfaces corrosion cannot occur. Innately acidic or alkaline deposits are troublesome on amphoteric alloys (those attacked at high and low pH—e.g., aluminum and zinc). 

Localized stagnation. Permeable deposits, crevices, preexisting cracks, and other conditions that result in physical shielding can lead to concentration of a corrodent in the stagnant solution, which can be 10-100 times or more greater than that measured in a bulk fluid (see Case History 9.1). 

Stratigraphic traps are formed by depositional and sedimentary factors. In such traps the depositional process and the follow-on cementing process, which changes the sediment bed into a rock, create porosity and permeability alterations in geometric forms that provide traps. 

Sedimentary deposits are usually carried to the region of deposition by water and are deposited in water. (In some cases deposits are carried by wind or ice.) It is within these water leposited sediments that hydrocarbons are likely generated from the plant and animal life that exists in these environments. Two principal properties of the sedimentary rocks that form from such deposits are porosity and permeability. 

Deposits of sand, dirt or permeable corrosion products on the metal surface (a type of crevice corrosion that is referred to as deposit attack). 

Atmospheric exposure trials, carried out in Cambridge, established the fact that when rusty specimens were painted in the summer, their condition, after some years exposure, was very much better than that of similar specimens painted in the winter It was found that steel weathered in Cambridge carried spots of ferrous sulphate, deeply imbedded in the rust, and that the quantity of ferrous sulphate/unit area was very much greater in the winter than in the summer this seasonal variation was attributed to the increased sulphur dioxide pollution of the atmosphere in the winter, caused by the combustion of coal in open grates. It was concluded that there was a causal relationship between the quantity of ferrous sulphate and the effective life of the paint. It was suggested that these soluble deposits of ferrous sulphate short-circuit the resistance of the paint film and, since paint films are very permeable to water and oxygen, the ferrous sulphate will become oxidised and hydrolysed with the production of voluminous rust, which will rupture the film at numerous points, thus giving rise to the characteristic type of failure seen on painted rusty surfaces. 

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