Fluid rate enhancement from massive sand production in heavy-oil reservoirs

In this paper, we consider sand production instability as the result of wellbore fluid pressure reduction (drawdown) below some critical level. A continuum model for massive continued sand production is developed by coupling fluid flow and granular matrix flow. This model shows the typical significant fluid rate enhancement which accompanies continuous sand production. The model provides a physical mechanism for propagation of a yielding front away from the wellbore as the process of sand production continues. Mass-balance analysis leads to a relation between cumulative sand production and the current yielding front location. Short-term enhancement of fluid production because of simultaneous sand production turns out to be dependent not only on instantaneous sand flux, but also on the current radius of the yielded zone around wellbore, that is, the history of sand production for the well. Long-term enhancement is stipulated mainly by growth of a yielded, highly permeable zone around the wellbore.