Displacement pressures

Following this, c+ is no more an independent field and, thus, the governing equations can be transformed into a displacement-pressure-concentration formulation allowing for an efficient numerical treatment within the FEM. 

Mercury Injection data revealed a porosity of 30 % and a bimodal pore size distribution with pore size maxima at 20 and 110 nm. The capillary displacement pressure (Pd) for mercury was 2.7 MPa corresponding to an equivalent value of 0.5 MPa. For the conversion from the mercury-air to the gas-water system the following parameters were used interfacial tension values of p(Hg-air) = 480 mN/m, and p(N2-water) = 70 mN/m contact angles (Hg-air) = 141°, and 6l(N2-water) = 0°. 

Table 2. Comparison between data from Mercury Injection (Hg) and gas breakthrough experiments (TV.) "N." denotes the N. displacement pressure converted from mercury data to the system N. -water.

Table 39—Displacement Pressures for Organic Liquid-Water-Solid Interface Systems. (Bartell and Osterhof, 1927)...

Displacement pressure (g per sq cm) Adhesion tension (dynes per cm) Displacement pressure (g per sq cm) Adhesion tension (dynes per cm)... 

The displacement pressure is a rock property and is defined as the force required to replace water from a cylindrical pore with oil or gas. Hence the displacement pressure determines the minimum buoyancy pressure needed for migration. 

The sealing capacity of a rock under hydrostatic conditions is determined by the minimum hydrocarbon-water displacement pressure of the rock, which depends on the radius of the largest connected pore throats in the rock and the oil-water and gas-water interfacial tensions, and in addition on the densities of groundwater and hydrocarbons accumulating in the adjacent reservoir rock. The maximum height of an oil or gas column that can accumulate below a seal is given by Equation 4.17 (Section 4.1.3)... 

Permeability and capillary displacement pressure (defined as the pressure at which significant wetting phase saturation of the seal occurs, commonly 5% of the pore volume) are related by an inverse function (Fig. 3) (Ibrahim et al., 1970) ... 

Fig. 3. Plot of displacement pressure against permeability for a wide range of undifferentiated lithologies (including shale, limestone and anhydrite) measured under in situ conditions. Dataset of Ibrahim et al. (1970).

Seal properties Rock seal properties are usually described in terms of their capillary pressure characteristics, primarily wettability, entry and displacement pressures, and irreducible wetting phase saturation. Wettability defines which fluids will preferentially occupy the smallest rock pores. Entry pressure is the capillary pressure at which the non-wetting phase first displaces the wetting phase, while displacement pressure is the capillary pressure at which the non-wetting phase first forms a continuous network within the pore structure. The irreducible wetting phase saturation describes the initial connate fluid saturation at the top of the capillary column. 

These two books provide a good overview and considerable detail about all aspects of measurement systems, including specific systems for force, temperature, displacement, pressure measurement, etc. Lyons, L., A Practical Guide to Data Analysis for Science Students, Cambridge University Press, Cambridge, 1991. 

Critical displacement pressure vs. mean pore diameter [29]. 

We can also classify sensors in terms of the quantities that they measure. Physical sensors are used in measuring physical quantities, such as displacement, pressure, and flow, whereas chemical sensors are used to determine the concentration of chemical substances within the host. A subgroup of the chemical sensors that are concerned with sensing the presence and the concentration of biochemical materials... 

A liquid jet emanating from a nozzle into an ambient gas may breakup into small drops when it is subjected to even minute disturbances. These disturbances may be in the form of surface displacement, pressure or velocity fluctuations in the supply system or on the jet surface, as well as flucmations in liquid properties such as temperature, viscosity, or surface tension coefficient. The instability and breakup of... 

Comparison of entrapment and mobilization The foregoing result can be used to provide a comparison of the conditions required for prevention of entrapment with those required for mobilization of trapped liquid. Movement of a trapped blob involves drainage at the leading edge of the blob and imbibition at the rear (see Figure 14). For a completely wetted random sphere pack, the pressure drop required for mobilization, AP, is given by the difference between drainage and imbibition displacement pressures (3,12,13). At 70% water saturation, these pressures are 6.7a/R... 

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