Flood pattern optimization of horizontal well injection

To optimize well spacing and injection rate in horizontal well flood pattern, formulae of the reasonable injection rate and well spacing are derived under fraction and no-fraction conditions respectively using filtration theory. The formulae take into account the fluid flow in low-permeability and thin reservoirs, and assume that horizontal well injection is rigid water driving. According to these formulae, the influencing factors of pressure loss on the horizontal section are diameter of casing pipe, production rate, and length of horizontal section. For a well with fixed casing diameter and horizontal section length, the influencing factors of pressure loss on horizontal section is only production or injection rate; for a reservoir, the influencing factors of maximal well space are length of horizontal section, oil production rate and water injection rate. The research results are applied in the Hade 4 thin layer sandstone reservoir of Tarim Oilfield. The designed flood pattern decreases injection pressure, augments injection, and keeps field pressure.