Porosity, types

TABLE 9.6 Comparison of Single Porosity Type and Linear Mixed-Bed SEC Columns... 

Use size prefixes with basic porosity types ... 

EXAMPLES solution enlarged x ratio of porosity types (1 2)... 

FIGURE 3.1 Classification of porosity types. (After Choquette and Pray, 1970.)... 

Earlier investigations presented in the papers [4,14] suggest a higher selectivity of adsorption in respect to preferentially adsorbed component for adsorbents containing narrower mesopores. Similar effect should be expected for microporous materials In order to study the influence of porosity type on adsorption from liquids the measurements of specific surface excess isotherms were performed for binary liquid mixtures benzene + n-heptane / carbon AC-2 and AC-4 benzene + 2-propanol / carbon AC-2 and AC-4. 

These additional studies carried out by the Krasnodar Scientific Research and Project Development Institute have thus disproved the earlier interpretation of the oil trap as a reservoir of fracture porosity type. 

With permeability values of 1400 Darcies and with oil viscosities of 2,0(X)-4,000 centipoise, the crude should have normal mobility in any reservoir rock characterized by macroporosity. The producing formations in the Abino-Ukrainsk field are essentially of this porosity type. Like the Zybza field, the Abino-Ukrainsk field also has some reservoir rocks of the microporosity type. Inasmuch as the oil in the reservoirs of the latter type is not mobile, only the oil-bearing horizons of macroporosity type are being worked during the early production stage of the field. 

Two types of reservoirs, each with different permeability, are found within the petroliferous bed of the fields in the Krasnodar Petroliferous Region. A number of laboratory models were therefore prepared to reproduce these permeability differences. Models using sand as porous medium (porosity-type models) simulated the reservoirs of the first type. The range of permeability of this medium corresponded to that of the actual reservoirs of the same type. Models characterized by fracture-type porosity (fracture-type models), were used to represent the second type of the reservoir. Again, the permeability characteristics of the medium used in the latter type models were similar to those of the real reservoirs. 

In experiments, the drainage and extraction of crude oil were studied separately for the fracture-type and for the porosity-type reservoirs. The corresponding types of models were used to study each of the two reservoir types. 

Employed in the first series of experiments was the porosity-type (granular) model having absolute permeability (k) - 5.2 Darcies. The effect of the rate of pressure reduction on ultimate recovery was studied. The initial formation pressure used in these experiments was 100 kg/cm. In the course of each experiment, the pressure at the exit point from the reservoir model was being reduced at a constant rate. 

The experiments showed strong effect of reservoir permeability on oil recovery. For example, the model of the petroliferous bed of microporosity tjrpe but with permeability of 294 Darcies gave an oil recovery factor of 60%, whereas the same porosity-type reservoir but with permeability of 5.2 Darcies yielded only 30% of oil in place. 

First, a discrete block is selected in an oil field which is made up mostly of reservoir sections of microporosity type and of some sections of macroporosity (fracture porosity) types. Next, wells are drilled into this block at close spacing of not more than 100 m either on a checkered grid or in rows. The cyclic steaming of the reservoir block follows according to a pre-set plan. With the arrangement of wells in rows, steam is injected into the second line of wells. The row of production wells is in the middle. 

Reduced heat loss represents one of the advanta s of the cyclic-steaming-by-block. In this connection, special studies should be carried out to develop methods for determining heat losses in oil-bearing formations with reservoirs of fracture porosity type. Such methods are not available at the present time so that it is difficult to make even any approximate calculations. 

It is necessary to pass the water sample through a filter of specified porosity, type, and quality when a determination of the concentration of dissolved inorganic constituents has to be made. Some filters and filtration apparatus may require laboratory pretreatment and must also be rinsed with a portion of... 

Targeted application Porosity type Fabrication technique Membrane thickness (microns) Reference example... 

The crystal carbonate fiicies is a secondary dolomitic texture characterized by the dominance of well-developed dolomite crystals. The most cxnnmon porosity types in the dolomitized parts are i) moldic and vuggy porosity, ii) intercrystalline matrix porosity iii) iniraciystalline porosity due to the selective dissolution of crystalline dolomite iv) karst and firacture porosity. The pore structures vary fiom monomodal to trimodal with an incr e of porosity and permrability according to the development of vugs and karsts. In this fiides, the reservoir properties are mainly controlled by the crystal size. 

Table 5. Comparison of single porosity-type and linear mixed-bed CPC columns.

Thickness, density, porosity, type (homogeneous or layered), and color should be noted. When only a limited amount of deposit is available, replication tape is a useful method of removing it. Polyvinyl chloride (PVC) or other chloride-containing tapes should not be used on stainless steels, which are susceptible to chloride pitting and stress cracking. 

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