Thermochemical-Pulse Fracturing of Tight Gas: Investigation of Pulse Loading on Fracturing Behavior

Abstract

Unconventional and tight gas reservoirs are located in deep and competent formations, which requires massive fracturing activities to extract hydrocarbons. Some of the persisting challenges faced by operators are either canceled or non-productive fractures. Both challenges force oil companies to drill new substitutional wells, which will increase the development cost of such reservoirs. A novel fracturing method was developed based on thermochemical pressure pulse. Reactive material of exothermic components are used to generate in-situ pressure pulse, which is sufficient to create fractures. The reaction can vary from low pressure pulse, to a very high loading up to 20,000 psi, with short pressurization time. In this study, Finite Element Modeling (FEM) was used to investigate the impact of the generated pressure-pulse load, by chemical reaction, on the number of induced fractures and fracture length. Actual tests of pulsed fracturing conducted in lab scale using several block samples compared with modeling work. There was a great relationship between the pressure load and fracturing behavior. The greater the pulse load and pressurization rate, the greater the number of created fractures, and the longer the induced fractures. The developed novel fracturing method will increase stimulated reservoir volume of unconventional gas without introducing a lot of water to formation. Moreover, the new method can reduce formation breakdown pressure by around 70%, which will minimize number of canceled fracturing.

Assessment of Saturation Effect on Hydraulic Fracturing in Sandstone and Thermally Treated Granite

“…The analysis of obtained fracturing results revealed a strong correlation between the mechanical properties of the rock and the parameters of fracture generated in the rock. The unheated granite is characterized by the highest Young's modulus and compressive strength values, and the highest value of BP was predictably observed, similar to [43]. Meanwhile, BP and fracture aperture, as well as their mechanical parameters, decreased in both mineral-oil-saturated sandstone and TT samples, shown in Figures 21 and 22.…”