A pressure pulse, known as a water hammer, can occur immediately after water-injection wells are shut-in for emergency or operational reasons. Large pressure pulses may cause wellbore-integrity problems such as sandface failure and sand production. We propose a new work flow to simulate water-hammer events, the resulting wellbore failure, and sand production in water injectors. On the basis of the results of this work flow, recommendations are made for wellbore design and shut-in protocols for water-injection wells.
For the first time, the results presented in this paper allow us to quantitatively understand the role of well shutdowns and subsequent water-hammer pressures on sand production. The failure of unconsolidated sands near the wellbore is affected by water-hammer events and their amplitude, period, and attenuation. If a water-hammer event occurs during the shut-in of water injectors, the extent of the sand failure becomes larger, and the failure zone continues to propagate along the stress-concentration direction. The simulation results clearly show the parameters that are important and suggest changes to well operations such as proper shut-in protocols that help to minimize the possibility of sand production. The results also suggest ways in which injectors can be designed to minimize the impact of water-hammer events.