The scale effect of the hole size on the onset and development of sand production was studied in a series of sand production tests with fluid flow on outcrop sandstone specimens. The onset of sand production was shown to vary inversely with hole size, in agreement with established results. The rate of produced sand was dependent on the hole size only for some types of rock. This dependency is explained on the basis of the cavity geometry and area of potential erosion for the different sandstone classes. For brittle sandstones showing slit-like erosion pathways, hole size dependency is negligible, while for sandstones where breakouts are the main source of sand production, sand rate scales roughly as the square of the hole size.
Sand production is a considerable and persistent challenge to the petroleum industry. The simultaneous flow of sand with the producing hydrocarbons may potentially erode tubing and valves, clog completion equipment, interfere with down hole operations, and present separation, handling and disposal issues. Several attempts have been made at modeling sand production. Predicting the evolution of sanding rate over time is inherently more complicated than simply predicting the sanding onset, because the phenomenon is a combined hydrodynamic and geomechanic process involving both failure mechanics and erosion by fluid flow. In addition, long term effects such as reservoir depletion and compaction, increased water cut, and changes in production schemes may influence sand production. Sand quantification and maximum allowed sand rate are becoming important design parameters in sand management. Instead of producing strictly sand free (sand control), which may impose unrealistic restrictions many wells may produce more economically by allowing some and production (sand management). This is especially relevant as more fields are becoming mature. Thus, there is a need for reliable volumetric sand production models.