Hydrajet-Based Fracturing Treatment in Unconventional Wells

Abstract

The success of resource shale development has drawn much attention to develop new technologies to economize the extensive fracturing treatments required to make commercial wells. While a single planar hydraulic fracture is the objective in conventional wells, generating a complex fracturing network is commonly the goal when fracturing unconventional wells. Therefore, in shale formations, it is required to establish connectivity to natural fractures and beddings to generate large Stimulated Reservoir Volume (SRV). Two main staged fracturing techniques have been implemented to complete horizontal wells drilled in the challenging unconventional reservoirs: plug-and-perf and sliding sleeves. This paper presents a technique for effective fracture stimulation, including hydrajetting for fracture initiation, then continuous injection for fracture propagation. Hydrajetting is used to place singular or dual miniholes of approximately 2-in. ID and 2 ft penetration depth to bypass the near wellbore stress field and focus the energy on generating SRV at a distance away from the disturbed near wellbore stress field (due to drilling effects). The procedure involves two steps: hydrajetting at a given depth using coiled tubing equipped with a gravity-oriented jetting tool, and then fracturing by pumping through both the annulus and the jetting tool. Large miniholes offer minimizing the energy loss created by conventional perforations, avoiding tortuous path generation, minimizing possibilities for near wellbore screen-out, and generating complex fracture networks. This paper discusses the unique mechanics of the new procedure aimed at creating large SRV in shale formations. The new technique is fairly easy to implement and the beneficial impact could be substantial. The technique and resulting benefits in fracture stimulation of shale reservoirs will be presented.