Mechanics of Sand Production for Acting Wells

Abstract

Sand production from a poorly consolidated formation during gas, oil or water recovery is a traditional, but unsolved problem of petroleum and geomechanical engineering. In practice sand production can be avoided by simply limiting production rates of the wells by reducing the pore pressure gradients. Correspondingly, it is necessary to determine the maximum possible filter velocity, above which sand grains (fragments of totally destroyed formation matrix) or fines (damaged products of the matrix) begin to move in pore channels. Moreover, their accumulation in the close vicinity of the well can lead to “thrombosis” of pore channels, because of convergent underground flows in the formation. The value of the critical velocity for sand production beginning (Lapuk, 1948) depends on the mechanical properties of the matrix — its composition, cementage, strength, etc.