Assessment of Sand Production Mechanisms and Completion Design Implications in Shallow Unconsolidated Sands of OML 26, Bayelsa State

Sand production from weakly consolidated Agbada Formation sands in the Niger Delta poses major challenges for well integrity, surface processing equipment, and environmental management in shallow reservoir developments in Bayelsa State. This study assesses the sand production mechanisms and evaluates completion design options for selected wells in OML 26, operated in Bayelsa State, South South Nigeria. Formation mechanical property data including uniaxial compressive strength, Young's modulus, and friction angle were compiled from wireline log interpretations and available laboratory measurements from archived well files. A sanding prediction workflow based on the Mohr-Coulomb failure criterion was applied to identify critical drawdown pressure limits beyond which sand failure initiates. Results indicate that critical bottomhole flowing pressures below 1,800 psi trigger sanding onset in the shallowest reservoir intervals, while deeper, better-cemented sands tolerate drawdowns up to 3,200 psi. Three sand control completion options were evaluated: gravel packing, stand-alone screens, and frac-pack designs. Economic sensitivity analysis indicates that frac-pack completions offer the best long-term rate versus cost profile for high-productivity wells, while stand-alone screens are adequate for lower-rate wells with moderate sand production risk. The study provides practical completion selection guidelines calibrated to OML 26 geomechanical conditions. Keywords: sand production, sanding prediction, Bayelsa State, completion design, Niger Delta.