Simultaneous height growth of multiple hydraulic fractures in layered reservoirs

The simultaneous hydraulic fracturing is a critical technique in developing shale oil/gas from unconventional hydrocarbon reservoirs with ultralow permeability. In this technique, multiple hydraulic fractures are closely placed to expect to grow simultaneously and thus enhance reservoir permeability. However, field data indicate their height growth is seldomly simultaneous, because some of them are often either impeded or overgrown. A too-short fracture height lowers the hydrocarbon productivity. In contrast, the overgrown fracture height may leak the hydrocarbon and fracturing fluid into the shallow aquifers. Why this unsatisfied multi-fracture height growth often occurs is still not fully understood yet. Here we establish numerical models to reproduce and simulate this process. We show that the layering structure of unconventional reservoirs impedes the simultaneous multi-fracture height growth significantly. We highlight that the impediment effect of layering structure depends on the stress interaction among hydraulic fractures. Our result can help field operators to increase productivity in the hydrocarbon industry and benefit natural fluid-driven activities like dyking and more.