Effective parameters for sand production in unconsolidated formations: An experimental study

Abstract

Abstract Sand production during hydrocarbon production is a crucial problem in the petroleum industry. Although extensive research has been conducted in the past, there is a need to gain a better understanding of the sand production mechanisms from unconsolidated and weakly consolidated sand reservoirs, in order to develop a predictive model to quantify sand production. The main objective of this study is to examine factors influencing sand production from a screen. Such knowledge can be effectively used to minimise sand production in the field. First, a new sand production cell was designed and developed to study the sand production process. The cell constructed with a Perspex screen enables observation of the sand production process in real time through a slot simulating a wire wrapped screen or a slotted liner. The cell was then used to investigate the factors that affect sand production in unconsolidated sand formations, including the slot size, injecting gas pressure, sand particle size and moisture content. Experimental results show that sand production is highly dependent on slot size, sand particle size, moisture content and injection pressure. The rate of sand production increases with increasing injection pressure due to the increase in drag forces acting on sand formation, and excessive injection pressures may cause total collapse in sand formation. Moisture content shows a negative influence on sand production because the inter-molecular attraction between sand particles increases with increasing moisture content. These preliminary experimental results appear consistent with the findings of past research, which demonstrates that the developed cell can be effectively used to study the sand production process in geological formations. A sand production model was then developed as a function of gas injection pressure and moisture content, which can predict cumulative sand production quite accurately when the outlet is 3 mm in diameter and the mean sand particle size is between 600 µm and 850 µm.