Sand Production in Vertical and Horizontal Wells in a Friable Sandstone Formation, North Sea

Abstract

Sand production is detrimental in oil and gas production. Sand-control measures include gravel-packing, drawdown control, sand consolidation, slotted liners, pre-packed screens, and frac-and-pack. Vertical wells can use any of these methods. Extended-reach, highly inclined wells, and horizontal wells close to water tables have very few cost-effective choices like slotted liners and open-holes. To predict the potential for sand production, a perforated completion was analyzed as an elastic-plastic spherical cavity while an open-hole horizontal well was analyzed assuming cylindrical symmetry. This analytical procedure was applied to investigate the feasibility of sand-free oil production from a friable sandstone formation in the North Sea. The calculated sand-free drawdown pressure of the horizontal well is more than twice that of the vertical-perforated well, depending on the drainage radius. Subsequently, in the North Sea single-well production test, a horizontal well was drilled and supported with a slotted liner only. The field test produced oil at high rates with no measurable amounts of formation sand.

An Accurate Characterization of Sand Strength in Weak and Unconsolidated Formations Aids Offshore Production Test Designs - A Bohai Bay Case Study

“…At relatively low flow rates, fluid drag does not affect arch stability but as flow rate increases, drag forces are sufficiently high to remove sand particles from the arch, thereby destabilizing sand bridges. If drag forces are too high, no sand arches are formed and sand production continues 1 . Fig.…”