The paper presents a horizontal well-design economically optimized by GA(Genetic Algorithm), which considers drilling location, various trajectories, and drilling cost. Previous designs for the production well have been limited at selecting the drilling spot and placing the fixed-shape trajectories to maximize the cumulative production. They are difficult to produce the systematic design that covers whole reservoir characteristics since they concentrated on only the location or the fixed trajectory for additional one well or two wells. Furthermore, they are incapable of fully investigating the interference effect among the producing wells in a heterogeneous reservoir as well as the profit maximization at the view point of economist.

The optimization model integrates GA with a node-based configuration that allows several kick-off points for the horizontal well-designs. The chromosome of GA involves the data regarding the location coordinates, the number of kick-off points, the trajectories, and the number of wells. The object function evaluates the profit consisted of production rate and cost information related to drilling and operation. Waterflooding with one injection well is carried out and the effect of inter-well interference is examined in a heterogeneous reservoir.

The developed model improves both profit and cumulative production comparing with the conventional vertical well-designs. The wells are distributed sparsely due to the interwell interference meanwhile they are assembled in higher permeable zones of a heterogeneous reservoir. The approach makes it possible the more reliable well-design considering several kick-off points, well placement, and various trajectories.

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