Maximizing tight gas recovery through a new hydraulic fracture optimization model

As the demand for gas increases worldwide, tight and deep unconventional gas reservoirs are becoming the target for development. However, for such reservoirs the conventional approach of simply fracturing the formation in such reservoirs to hydraulically stimulate the well is inadequate. This is because most currently available commercial software lack proper optimization tools in them and they do not take into consideration several key parameters and realistic constraints in them. An integrated but constrained model to optimize hydraulic fracture treatment has been developed to maximize gas production and net present value with minimum treatment cost. A dual objective function has been incorporated to satisfy operator's economic constraints and also to investigate trade-off between two conflicting design objectives. Model couples both the industry experience and design constraints based on hydraulic fracture mechanics. The global optimization scheme in the model is driven by an intelligent moving-object algorithm. Unlike commercial software, important design parameters are included as the free design variables which are randomly varied during optimization. Model has been successfully applied to a hypothetical deeper tight gas formation to demonstrate its merits. The optimum treatment design indicates a significant incremental production (by 300% compared to production from non-fractured tight gas well) at lower cost compared to production from non-fractured tight gas sand. Insightful parametric sensitivity analyses are also presented. This model could also be used to study the potential of the deep UAE gas sands.