Sanding onset for offshore depleted using critical drawdown pressure: A case study for well X cuulong basin in Vietnam

Abstract

This paper presents the reservoir pressure depletion will cause rock stress changes, which results in an increasing likelihood of serious sand production in the unconsolidated sandstone reservoir. This paper aims at offshore unconsolidated sandstone oil reservoir, analyzes rock stresses of the borehole wall with impact of reservoir pressure depletion on in-situ stresses on rock strength. A full review basic theory in geomechanics will be presented, such as: rock failure criterions, sanding critical drawdown pressure calculating model and a numerical calculating method for the model are developed. Furthermore, a case study sanding prediction method for pressure depletion of offshore oil reservoir in Cuulong Basin, Vietnam also is presented. Using the model analysis, on the other hand the chart of sanding onset is relatively large with the high formation pressure depletion. On the other hand, the sand will be appeared no matter how small the drawdown is.