A New Approach for Reducing Sand Production During Water Breakthrough from Semi-Consolidated Sandstone

Abstract

Abstract It is well recognized that most formations of semi-consolidated sandstone result in significant sand production during water breakthrough. In principle, the amount of sanding mainly depends on the rock strength and, subsequently, the reaction between the injected water and sand formation. Hence, this paper examines the sand (quartz) hydrolysis mechanism during water breakthrough to establish a correlation between silica dissolution and rock strength as a function of water saturation. Static and dynamic experimental approaches were used to correlate silica dissolution and rock strength as a function of water saturation. For the static method, pure quartz fine and coarse particles were utilized at different water compositions and temperatures to examine the reaction between the silica (quartz) and water. Then, selected cases were investigated further as a function of water saturation using a dynamic core flood test. The amount of silica reacted was monitored using a UV-Vis spectrophotometer, while the rock strength was investigated using uniaxial compressive strength. Semi-consolidated and consolidated sandstone core samples were employed for the dynamic tests. Based on the static experiment, the amount of sanding is significantly affected by the water quality (salinity) and pH. Results indicated that freshwater or distilled water has a higher impact on silica dissolution than brine water. Sodium chloride and Potassium chloride have the ultimate effect in silica dissolution in terms of hardness ions. In contrast, pH inconsistently impacts the silica dissolution, and an optimum pH value was selected. For the dynamic experiments, the results showed that an increase in water saturation leads to an increase in silica dissolution, which reduces the core strength. Sand production is, therefore, also a result of silica dissolution, which weakens the grain particles and connection at grain-to-grain contact. In conclusion, the water quality significantly impacts the amount of sand dissolved and the correlation between silica dissolution and rock strength as a function of water saturation was developed. The novelty of this paper is based on understanding the main reasons behind sand production for the semi-consolidated sandstone formation. The finding of this study is helpful in designing the optimum water quality used for water injection while reducing sand production issues.