Advanced Study of Pore Structure and Mechanical Property Change of Tight Sand Due to Thermochemical Treatment

The demand for unconventional gas is rapidly increasing to provide enough energy to maintain sustainable growth for industrial countries. Even oil producers can develop UG to be directed to internal industrial and power consumptions. As Unconventional gas reservoirs are located in deep high-stress formations, one of the critical challenges gas producers are facing is to develop a cost effective stimulation method that can reduce production cost to lower than Break-even. In this paper a novel stimulation method, based on thermochemicals, is introduced. Thermochemicals when injected in tight reservoirs generate localized pressure-pulses, which result in creating microfractures, improve permeability and increase stimulated reservoir volume (SRV). Tight core samples were treated with thermochemicals and the impact on mechanical properties were studied. Generated localized pressure was clearly detected during Coreflood treatment. Microstructural and mineralogical properties were also investigated using microscopy and spectroscopy. CT-scan, micro CT-Scan, Young's modulus, Poisson's ratio and ultrasonic velocities were measured pre and post treatment. Results showed creation of fractures and microfractures, which resulted in improved rock conductivity. Results show that, micro-factures are created inside the used sample due to the in-situ generation of heat and pressure. The density of those micro-factures is strong function of the chemical concentration and the injected volume. Creation of micro-factures leads to improve the formation conductivity and reduce the capillary forces, therefore, enhances the hydrocarbon recovery. The outcome of this study is to understand the impact of thermochemical treatment on rock integrity. The ultimate objective is to establish a relationship between the injected chemicals and the alterations of formation properties such as permeability and porosity. This work will serve as a baseline for designing and conducting thermochemical operations for hydrocarbon reservoirs. In this study a novel stimulation technique to increase stimulated reservoir volume (SRV) is presented. In basins with excessive tectonic stresses, the current novel treatment can become an enabler to deeply stimulate well stages which otherwise left untreated. A new methodology is developed to lower fracturing cost and increase unconventional gas production. A better connectivity reduces the required number of hydraulic fracturing-stages.