Productivity Enhancement in Multilayered Unconventional Rocks Using Thermochemicals

Elastic moduli contrast between the adjacent layers in a layered formation can lead to various problems in a conventional hydraulic fracturing job such as improper fracture height growth, limited penetration in a weaker layer only, and nonconductive fractures. In this study, the results of thermochemical fracturing experiment are presented. The hydraulic fracturing experiments presented in this study were carried out on four-layered very tight cement block samples. The results revealed that the novel fracturing technique can reduce the required breakdown pressure in a layered rock by 26%, from 1495 psi (reference breakdown pressure recorded in the conventional hydraulic fracturing technique) to 1107 psi (breakdown pressure recorded in the thermochemical fracturing). The posttreatment experimental analysis showed that the thermochemical fracturing approach resulted in deep and long fractures, passing through majority of the layers, while conventional hydraulic fracturing resulted in a thin fracture that affected only the top layer. A productivity analysis was also carried out which suggested that the fracturing with thermochemical fluids can raise the oil flowrate up to 76% when compared to a conventional hydraulic fracturing technique. Thermochemical fluids injection caused the creation of microfractures and reduces the linear elastic parameters of the rocks. The new technique is cost effective, nontoxic, and sustainable in terms of no environmental hazards.