Fit-For-Purpose Fracturing Technique Enables Breakthrough in Marginal Gas Field Development of Ordos Basin, China

Abstract Some areas in Ordos basin, such as Sudong block, suffer from poor economic returns caused by low production. The development of this reservoir has multiple geologic and engineering restrictions. In addition to the complex lithology and abundant clay content that reduce formation effective gas porosity and permeability, the low net-to-gross (NTG) ratio requires a larger quantity of proppant to adequately support a fracture that covers the entire thickness of the sand interval. Because of these issues, the reservoir potential is not capable of supporting costly conventional fracturing techniques. Finding a fit-for-purpose stimulation solution that balances the cost effectiveness and production enhancement has been a challenge for years. Channel fracturing has been introduced to achieve better fracture performance with less cost. A pilot project of one deviated well and one horizontal well was done in 2019. The goal of this step was to verify the subsurface suitability and engineering feasibility. Despite the smooth operation and record-breaking post-fracturing test results, multifaceted study continued. The laboratory study of proppant and formation rock established a solid foundation for fluid formulation and proppant concentration design. The design optimization with a multiphysics simulator minimized the fluid volume while ensuring conductivity and lateral coverage. Finally, the equipment layout and rate distribution among pumps was planned so that the slurry pulses formed at the blender would be delivered to downhole with integrity. These success of these efforts is proven by the outstanding post-fracturing results of two vertical wells and one horizontal well in 2021. Despite the discrepancy in reservoir quality, all the wells had faster cleanup period, less gas kickoff, and 80% increase in horizontal well absolute open flow (AOF) compared with 2019. As is demonstrated by field observation and production results, channel fracturing creates highly conductive channels in the fracture with less material consumption and less cost, sustainably. Compared to the conventional fracturing solution, channel fracturing technology enables balancing of budget saving and production increase. The success of implementation has led the way to a more economic cost model to develop the marginal fields in Ordos basin.