An experimental study and finite element modelling of thermochemical fracturing in ultra-tight cement mortar samples

Current global energy demand and supply gap needs the best engineering methods to recover hydrocarbons from the unconventional hydrocarbon formations. Unconventional hydrocarbons normally present in deep formations, where the overburden stresses and formation integrity are very high. When fracturing these types of formations, the hydraulic fracturing job becomes much more challenging, and in some scenarios, pumping reached to the maximum capacity limits without generating any fracture. This reduces the operational gap to optimally placed hydraulic fractures. In the present research study, a novel thermochemical fracturing approach is presented to reduce the breakdown pressure of the high-strength formations. The hydraulic fracturing experiments presented in this study are carried out on ultra-tight cement block samples. The composition of cement blocks is synthesized in this way that it simulates the real rocks. The results showed that the newly proposed thermochemical fracturing approach reduced the breakdown pressure in ultra-tight cement from 1095 psia (reference breakdown pressure recorded from conventional hydraulic fracturing technique) to 705 psia. The post treatment experimental analysis showed that the thermochemical fracturing approach resulted in a deep and long fracture while conventional hydraulic fracturing resulted in a thin fracture. In addition to that, a Finite element analysis using ABAQUS is also presented. The main purpose of the numerical investigation is to confirm the sufficiency of the experimental data for reproducing the same breakdown pressure that included depiction of injection pressure versus time plots, failure loads and cracking patterns.