Reducing the Sand Production from Semi-Consolidated Sandstone Formation by Mitigating the Silica Dissolution Factor During Water Breakthrough

Abstract

Abstract Sand production is a common problem associated with semi-consolidated sandstone due to the reaction between the injected water and sand formation. In this paper, the mechanism of quartz hydrolysis during water breakthrough is investigated to establish a relation between silica dissolution and rock strength as a function of water saturation. The study is conducted with static and dynamic experimental approaches to investigate the relationship between sand (quartz) and water, which is called quartz hydrolysis. The static approach used pure quartz fine and coarse particles at different water compositions and temperatures to find the reaction between silica and water. From static results, some cases have been selected to examine further through a dynamic approach (core flooding test) as a function of the water saturation. Then using a UV-Vis spectrophotometer to measure the silica concentration and dissolution rate. Whereas unconfined compressive strength is conducted to measure the change in sandstone core strength. The results regarding static conditions show that Distilled water has a higher impact on silica dissolution than the brine base. This is related to the saturation level of the solution reached. In terms of the pH effect, it has been found that the highest amount of silica dissolution is 12 pH then 3 pH. Meaning that at the highest pH 12 and lowest pH 3 the silica dissolution increases sharply. This is related to OH and H ions present in both high and low pH stimulating the reaction. Regarding salinity effect, it is seen that Sodium chloride and potassium chloride have the highest effect in silica dissolution. While for the core flooding test, the results show that an increase in water saturation leads to reduce the core strength as a function of an increase in silica dissolution, which weakens the grain particles and connections at grain-to-grain contact, ultimately reducing core strength and causing sand production. It is concluded that water quality has a significant impact on the amount of sand dissolved, and a correlation between silica dissolution and rock strength as a function of water saturation is established. This study’s findings are useful in designing optimum water quality for water injection and mitigating sand production issues in sandstone formations. Also, understanding the main reasons behind sand production for the semi-consolidated sandstone formation.