Geomechanical effects of oilfield chemicals on sand failure in reservoir rocks

Sand failure may result in the production of formation sand at the same time the formation fluids are being produced. This work examines the effects of some commonly used oilfield chemicals, specifically, biocide, corrosion inhibitor and scale inhibitor, on the geomechanical strength of reservoir rocks such as limestone and sandstone. A combination of rock mechanical testing, grain size distribution analysis and analytical techniques are used to establish and define the effects of these chemicals on grain dissolution and unconstrained compressive strength. The results suggest that some interactions such as chemical reaction (dissolution/precipitation) between the oilfield chemicals and the two different types of reservoir formation rocks and transport of grains occurred following the exposure of the rocks to the oilfield chemicals leading to the weakening of the grain fabrics rocks and consequent reduction in unconfined compressive strength. The implications of the results for the strength reduction and sand production are discussed.