Influence of sand production on pressure drawdown in horizontal wells: Theoretical evidence

Poorly consolidated reservoirs are susceptible to sand production that tends to increase the pressure drawdown along the well length. This problem, which has not received adequate attention in the literature of petroleum engineering, is quantitatively assessed in this paper. Different flow regimes typically encountered in two-phase transport systems of liquid and solid are discussed. In an effort to evaluate the degree of influence the presence of sand exerts on pressure drop, a suitable relation applicable for heterogeneous flow is employed to compute the energy gradient of the mixture. The difference in the energy gradient of pure oil and mixture is examined for horizontal pipelines in terms of volumetric solid concentration and flow velocity. The study demonstrates that for a specific sediment size and pipe roughness, the effect of sand movement on pressure drop cannot be ignored in many cases of poorly consolidated reservoirs, being 5.1–168% times greater than the pressure drop resulting from pure oil under the same flow condition.