Effect of Water Breakthrough on Sand Production: Experimental and Field Evidence

Abstract

Abstract It has been reported from different field operators that the onset of sand production in a particular field coincided with water breakthrough at the production wells. Several mechanisms have been proposed to explain these observations such as pore pressure gradient increase near perforations due to relative permeability effects, reduced capillary bond due to increased water saturation, and loss of rock cohesion because of chemical incompatibility between produced water and the reservoir rock. Yet, there does not seem to exist any systematic study of such a phenomenon on a large scale, neither capable of supporting any of the proposed mechanisms nor the statement that the onset of water breakthrough may trigger the onset of sand production. As a consequence, a vast campaign of physical model experiments of perforation cavities using field and outcrop material was undertaken to observe directly the effect of water breakthrough upon the onset of sand production. The experiments, have convincingly demonstrated that the two phenomena could not be linked directly, but that once sand production has initiated, water production could accelerate the sand influx thus making it more noticeable and problematic for daily operations. Finally, the problem of the coincidence of water breakthrough and onset of sand production has been analysed on a series of more than 40 oil and gas wells in weak sand reservoirs. This analysis of field data further confirms the laboratory and theoretical findings described in the paper.