Investigation of sand instability using geomechanics criteria for sanding prediction

Abstract

Sand production is a major problem in many petroleum fields. Sanding becomes more critical as operators follow more aggressive production strategies. Sand production occurs when the reservoir fluid, under high production rates, dislodges a portion of the formation solids leading to a continuous flux of formation solids into the wellbore; the sanding process may cause complex temporal and spatial changes in permeability in the near-wellbore region. For Thailand, especially onshore oil field, it is crucial to understand its behaviors of formation as producing sand in view of geomechanic criteria. The study focuses of sand failure by observing the induced stresses near wellbore. The formation failure case adopts the Mohr’s Coulomb failure criteria. The rock strength data are collected from the lab test of the onshore field Thailand in addition to its reservoir and production characterization. The variation of rock strength parameters in statistic terms, the reservoir pressure and permeability are tested in ECLIPSE model. Then, the responding induced tresses are observed leading to the indication of sand movement. As a results of this study show that the sensitivities of cohesion force has significant effect to sand failure. The sand movement is likely to initiate when the cohesion strength reduces to μ- stdv. at 920 psi. And, the confirmed sand movement is clearly stated when the cohesion strength reduces to μ-2 stdv. at 343.49 psi. While the other rock strength parameter, the internal friction angle, Poisson’s ratio, and Young’s modulus, have insignificant effect to sand failure. At the same analysis, the reservoir pressure and permeability show impact to induced stresses near wellbore.