Integrated model for multistage hydraulic fracturing of tight-gas reservoirs

As the demand for gas increases worldwide, tight, deep and multilayered unconventional gas sands are becoming the target for development. For such reservoir the conventional approach of simple fracturing the formation to hydraulically stimulate the well is inadequate. Continuous progress in hydraulic fracturing technology results in pinpoint multistage fracturing of multilayered vertical well and multistage transverse fracturing of horizontal well. However, the systematic design methods for fracture treatment parameters with constraints are not well presented in the literature. Even the 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.;Although the larger the number of fractures the higher the productivity, there are optimal number of fractures and optimum treatment parameters when real field constraints and economic aspects are considered. Two integrated but constrained models to design pinpoint multistage fracturing treatment of vertical multilayered tight gas wells and horizontal wells are developed in this work to maximize gas production, respectively. Models couple both the industry experience and design parameters based on hydraulic fracture mechanics. This integrates reservoir in-situ parameters, fracture geometry, fracture treatment design, realistic design constraints, and production and economic models.;The first integrated model has been successfully applied to a hypothetical deep and layered tight gas sands to demonstrate its merits. A parametric study is also conducted to compare between the conventional single-stage and pinpoint multi-stage hydraulic fracturing with their basic design concepts and post-fracture benefits. It is evident that the productivity increase is about 12-fold higher in pinpoint multistage fracturing compared to 7-fold for blanket fracturing.;The second integrated model has been successfully applied to a hypothetical horizontal tight gas reservoir to demonstrate its merits. A simple and accurate analytical approach is proposed for evaluating and optimizing the productivity. Some comparisons have been conducted between the integrated model and Meyer software, which showed reasonable agreements. Insightful parametric sensitivity analyses are also presented.;The integrated models proposed in this work could be used to study the potential of the deep UAE offshore tight gas sands, which is yet to be developed.