(Inhibition of Scales Deposited in oil Well) Iii-Morphological Study of Seed Growth in Absence and Presence of Scale Inhibitor

Th., Abdel-Moghny, *M. Ramzi, S. M. Desouky, and M. El-Batanoney

Egyptian Petroleum Research Institute, (EPRI) Nasr City- 117 27, Cairo (Egypt)

The crystal growth of calcium sulfate dihydrate and calcium carbonate (calcite form) have been studied in the absence of pentaethylene hexamine N-octa-methyl phosphonic acid (P2) after 24h of precipitation. Complementary microscopic studies have been made of the morphology on the crystal seed using a scanning electron microscope. The taken photos displayed that, the effect of the presence of 100 ppm of scale inhibitor on the calcium sulfate crystal morphology represented by marked difference and more little morphologies (rectangular to blocky calcium sulfate) from those grown in the absence of scale inhibitors (perfect prismatic crystals). In case of calcium carbonate scales, the effect of using the inhibitor was illustrated in the modification of the well-developed, small rhombic calcium carbonate crystals in absence of scale inhibitor to small, irregular, readily fractured crystals that do not adhere well to the surface. The results proved different inhibition mechanisms, solubility enhancement, crystal modification and dispersing activity.

Crystal growth; Crystals seed; Calcium sulfate dihydrate; Calcium carbonate (calcite form); Homogeneous nucleation