The creation of hydraulic fractures from horizontal wellbores is often characterized by unusual injection pressure behavior and has resulted in inconsistent post-treatment production. A methodology is presented for the design and evaluation of hydraulic fractures from horizontal and extended-reach wellbores, including economic analysis based on improved production forecasts. The requirements for designing appropriate treatments are stated, and the significance of each parameter is discussed. Reservoir scenarios are outlined and specific examples cited to describe specific production predictions relative to anticipated fracture morphology. The results from laboratory testing are used to exemplify the relationship between the orientation of the wellbore, in-situ stresses, and created fractures. In addition, effective perforating strategies and wellbore notching techniques for optimizing fracture initiation and propagation are described.
A knowledge of the orientation and magnitude of principal stresses is required in order to anticipate successful implementation of a treatment design. The ability to reduce the effects of near-wellbore restrictions is possible by influencing the initiation and, therefore, intersection of the fracture with the wellbore. Sealed experiments suggest this may be accomplished by controlled wellbore notching techniques, and in some cases, high-density perforating procedures. Predictions made using a production simulator can be used to explore possible scenarios and by using a non-Darcy correlation can provide improved accuracy in forecasting results.