Perpustakaan Digital ITB

A long-standing problem in the oil and gas industry is sand production in unconsolidated sandstones. Basically, during the oil recovery process, the pumping of the fluid induces huge drag forces that dislodge sand particles from the solid skeleton as the mechanical (inter-granular) strength of the formation is exceeded. The sand fragments are carried into the wellbore where they can block the flow, damage pumps and pipes, and contaminate the produced fluid. With time, sand production creates cavities in the formation that continually increase in size and eventually lead to wellbore instability and failure. In this publication, the author uses the steady state model developed by Geilikman et al to model a one dimensional continuum model for the sand production. Decreasing of fluid pressure in the wellbore creates an excessive stress that can cause instability. This mechanism leads to massive solid flux (plastic flow) and this plastic flow can be a major factor in sand production. Dynamic and mass transport properties related to sand production after the appearance of yielded zone, including the process of radial propagation of the yielded zone around the wellbore and several sand control techniques are also investigated in this paper. The results will be estimated using numerical method to verify the equations. It is found that, with this new semi-analytical model, the numerical results for porosity, radius of the yielded zone, and cumulative solids production are physically reasonable. The new equation and its computer implementation can also provide an insight on the dynamic properties of sand propagation, altered zone porosity, the evolution of “yielded zone radius”, and cumulative sand production using simple numerical method for various scenarios.