Hydraulic fracturing effectiveness depends on the cost and properties of the selected propping agent. The methods and fluids that create fracture width and transport the proppant along the fracture width also have a significant impact. Recent advancements related to channel fracturing design, execution, and evaluation addressing all these components have enabled proper modeling and further treatment optimization. This work provides a detailed overview of several years of laboratory experiments, research, modeling, and global field testing of enhanced channel fracturing methods.
Channel fracturing is well known for breaking the link between fracture conductivity and proppant permeability by replacing a continuous proppant pack with open channels inside the fracture using intermittent proppant feeding. To prevent proppant settling during fracture closure, degradable fibers have been effectively utilized within the fracturing fluid for over 10 years. This technique achieves maximum fracture conductivity while minimizing proppant cost. Decoupling proppant performance and fracture conductivity enables replacing ceramics by natural sand, thereby significantly improving field development economics in many areas of the world. Furthermore, extensive laboratory research has qualified new fibers for application of channel fracturing across a wider reservoir temperature range.
Research and laboratory experiments were conducted to construct a workflow to model and optimize sand transport and the resulting channel geometry. Fiber and proppant transport modeling results compare extremely well with experimental results and provide excellent resolution and accuracy. This work also demonstrates that intermittent pulses of proppant with fiber effectively creates reliable channels in the fracture. Also, improved software and equipment enhancements allowed accurate fiber and proppant synchronization, making the placement of fiber-free channels possible.
Recently developed advanced modeling tools have improved understanding of channel formation in the fracture, thereby enabling treatment design optimization. The enhanced models further enable evaluation of different materials selection, for instance, replacing ceramic proppant with natural sand in the channeled area of the fracture. A comprehensive case study of channel fracturing implementation in Saudi Arabia proved the method to be effective for improving proppant placement and fracture geometry to yield improved incremental production. Another field case in the region demonstrated the ability to replace ceramic proppant with natural sand without sacrificing any channel conductivity.
The study breaks new ground in the stimulation of extreme low temperature and high temperature formations by extending the channel fracturing technique, enabled by the introduction of a new solids transport concept and the development of new fiber compositions. When combined with accurate modeling, improved economic results were achieved by using locally produced sands to replace ceramic proppant while consistently delivering highly conductive fractures. The project includes laboratory testing, a detailed simulation model description, and field examples.