Prediction of mineral scale formation in geothermal and oilfield operations using the extended UNIQUAC model

Progress on the relationship between miR-125 family and tumorigenesis

“…The position relevant to maximum scale precipitation and composition of final brine in producing well were obtained by using the geometry of reservoir, geometry of well and precipitation reaction rate.Sheikholeslami(2005)defined scaling potential index (SPI) as the difference between the measured pH and saturated pH of the brine for studying of the calcium carbonate scale formation. In this model, the saturated pH was calculated using the equilibrium constants, calcium carbonate solubility product and Pitzer activity coefficient Garcia et al (2005). developed an accurate thermodynamic model for calculation of the sulfate and carbonate salts solubility under hydrothermal conditions, i.e.…”

Prediction of the freezing point of multicomponent liquid refrigerant solutions

“…For example, the ion Ca +2 is smaller and it has a higher charge than K + , therefore the hydration effect would be more important in the system with CaCl 2 than in the system with KCl. Other source of error may be related to the fact that the UNIQUAC parameters used were obtained for a temperature range above 0°C and therefore, higher Table 5 UNIQUAC q and r parameters (Thomsen et al, 1996;García et al, 2005García et al, , 2006 Table 6 UNIQUAC interaction parameters u o ji (Christensen and Thomsen, 2003;García et al, 2005García et al, , 2006 Table 7 UNIQUAC interaction parameters u t ji (Christensen and Thomsen, 2003;García et al, 2005García et al, , 2006 extrapolation errors may be expected in the temperature range of liquid refrigerants. Although there are practically unlimited possibilities to combine constituents and to formulate appropriate multicomponent solutions, there are scarce data related to their freezing points.…”

“…The extended UNIQUAC parameters for the study cases were obtained from Thomsen et al (1996), Christensen and Thomsen (2003), García et al (2005) and García et al (2006) (Tables 5-7).…”

Energetic Use of EGS Reservoirs

“…Attempts to predict mineral scale formation in geothermal systems by modeling have been made for example, by Garcia et al (2005) and Garcia et al (2006) who used the UNIQUAC model to predict sulfate and carbonate scaling or by Duan et al (1996) to predict scaling with GEOFLUIDS and TEQUIL. However, these codes are usually strongly simplified due to the high complexity of these systems (usually extremely high ionic strength, very high pT conditions, and involving several phases) and consequently lack adequate equilibrium constants.…”