An experimental study was undertaken to examine formation damage due to plugging caused by precipitates and scales generated from the dissolution of silicate compounds and associated minerals. The experimental tests include: roller oven tests, petrographic, SEM and EDEX studies. The tests were carried out at various temperatures (200°F to 500°F) and steam alkalinity in order to ascertain the factors and conditions that lead to formation damage and wellbore erosion during steam injection.

The results from this investigation indicate that elevated temperatures (above 200°F) as a factor can cause irreversible formation damage because of hydrothermal effects. Also high PH causes irreversible formation damage mostly due to hardness precipitation from divalent ion exchange processes. The combined effect of temperature and alkalinity increases the degree of formation damage at low temperatures (below 200°F). However, at high temperatures, the more severe formation damage caused by increased alkalinity can be reduced by thermal effects. Formation crystals and precipitates seems to be hindered at temperatures above 300°F. SEM, X-Ray, EDEX and petrographic analyses show pseudo-hexagonal stacks of mineral overgrowth which blocked pore throats. The SEM micrographs show the dissolution of certain minerals such as kaolonite and the precipitation of aluminosilicate compounds such as zeolite.

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