A 150 lbf thrust class, modular, bi-propellant, rocket engine/gas-generator and supporting test infrastructure has been developed in a cooperative effort between Sandia National Laboratories and the New Mexico Institute of Mining and Technology’s (NMIMT’s) Energetic Materials Research and Testing Center (EMRTC). This modular test engine design consists of a head end fuel-oxidizer injector, a spark ignition gaseous H2/O2 torch igniter, combustion chamber and nozzle module. This robust design allows for rapid configuration changes as well as economical repair should hardware become damaged in testing. The engine interfaces with a permanently installed pressurizing system capable of delivering liquid nitrous oxide and a variety of liquid fuels for both rocket engine development and propellant performance evaluation. The regulated high pressure systems allow for delivery of liquefied gases above their saturation pressure as well as allowing for high pressure rocket engine/gas-generator operation. The facility test cell houses a 1 ton thrust capacity test stand leaving room for larger scale engine development.
During the initial phase of this SubTER project, we conducted a series of high resolution seismic imaging campaigns designed to characterize induced fractures. Fractures were emplaced using a novel explosive source, designed at Sandia National Laboratories, that limits damage to the borehole. This work provided evidence that fracture locations could be imaged at inch scales using high-frequency seismic tomography but left many fracture properties (i.e. permeability) unresolved. We present here the results of the second phase of the project, where we developed and demonstrated emerging seismic and electrical geophysical imaging technologies that characterize 1) the 3D extent and distribution of fractures stimulated from the explosive source, 2) 3D fluid transport within the stimulated fracture network through use of a contrasting tracer, and 3) fracture attributes through advanced data analysis. Focus was placed upon advancing these technologies toward near real-time acquisition and processing in order to help provide the feedback mechanism necessary to understand and control fracture stimulation and fluid flow. Results from this study include a comprehensive set of 4D cross-hole seismic and electrical data that take advantage of change detection methodologies allowing for perturbations associated with the fracture emplacement and particulate tracer to be isolated. During the testing the team also demonstrated near real-time 4D electrical resistivity tomography imaging and 4D seismic tomography using the CASSM approach with a temporal resolution approaching 1 minute. All of the data collected were used to develop methods of estimating fracture attributes from seismic data, develop methods of assimilating disparate and transient data sets to improve fracture network imaging resolution, and advance capabilities for near real-time inversion of cross-hole tomographic data. These results are illustrated here. Advancements in these areas are relevant to all situations where fracture emplacement is used for reservoir stimulation (e.g. Enhanced Geothermal Systems (EGS) and tight shale gases).
Here, a liquid bi-propellant rocket engine and supporting infrastructure has been de-signed, constructed, and tested at New Mexico Institute of Mining and Technology ina cooperative effort with Sandia National Laboratories. The modular engine designconsists of a head-end fuel-oxidizer injector, gaseous H2/02 torch ignitor, combustionchamber, and nozzle modules. The robust modular design allows for rapid config-uration changes and component replacement if damaged in testing.
During the initial phase of this Department of Energy (DOE) Geothermal Technologies Office (GTO) SubTER project, we conducted a series of high-energy stimulations in shallow wells, the effects of which were evaluated with high resolution seismic imaging campaigns designed to characterize induced fractures. The high-energy stimulations use a novel explosive source that limits damage to the borehole, which was paramount for change detection seismic imaging and re-fracturing experiments. This work provided evidence that the high-energy stimulations were generating self-propping fractures and that these fracture locations could be imaged at inch scales using high-frequency seismic tomography. While the seismic testing certainly provided valuable feedback on fracture generation for the suite of explosives, it left many fracture properties (i.e. permeability) unresolved. We present here the methodology for the second phase of the project, where we are developing and demonstrating emerging seismic and electrical geophysical imaging technologies that have been designed to characterize 1) the 3D extent and distribution of fractures stimulated from the explosive source, 2) 3D fluid transport within the stimulated fracture network through use of a contrasting tracer, and 3) fracture attributes through advanced data analysis. Focus is being placed upon advancing these technologies toward near real-time acquisition and processing in order to help provide the feedback mechanism necessary to understand and control fracture stimulation and fluid flow.
During the initial phase of this SubTER project, we conducted a series of high resolution seismic imaging campaigns designed to characterize induced fractures. Fractures were emplaced using a novel explosive source that limits damage to the borehole. This work provided evidence that fracture locations could be imaged at inch scales using high-frequency seismic tomography but left many fracture properties (i.e. permeability) unresolved. We present here the methodology for the second phase of the project, where we will develop and demonstrate emerging seismic and electrical geophysical imaging technologies that characterize 1) the 3D extent and distribution of fractures stimulated from the explosive source, 2) 3D fluid transport within the stimulated fracture network through use of a contrasting tracer, and 3) fracture attributes through advanced data analysis. Focus will be placed upon advancing these technologies toward near real-time acquisition and processing in order to help provide the feedback mechanism necessary to understand and control fracture stimulation and fluid flow.
The development of enhanced or engineered geothermal systems (EGS), by definition, includes an engineered approach to reservoir stimulation. EGS require an effective method of generating a high surface area network of fractures, or the stimulation of existing fractures, in a formation in order to increase permeability/heat-transfer. The most accepted methodologies include hydraulic fracturing and chemical stimulation. Alternative methods employing energetic materials have been employed for reservoir stimulation. For oil & gas reservoirs, this has been accomplished in the past with solid propellant gas generators and high explosives but the pressurization rate and final pressure cannot be controlled or easily adjusted in the field. Our program is investigating controlled and tailored rapid gas generation from solid, liquid and gaseous energetic formulations to operate in the chasm between conventional propellants and solid high explosives. This distinct solid, liquid and gas phase energetic materials approach has specific attributes and that could be used synergistically or individually to enhance a specific formation. This may prove to enhance the viability of using geothermal resources for power production. By employing optimized energetic materials we can tailor burn rates above propellant burn rates to optimize the gas generation rate without entering the excessive realm of the high pressures generated by high explosives. Gas phase energetic materials offer a unique method of tailoring reaction rate and final pressure. Again, rapid pressurization at rates, far exceeding quasi-static conventional hydraulic rates, can generate multiple radial wellbore fractures and potentially provide a mechanism to induce shear destabilization within the formation that enables the fractures to be self-propping. Multiple fractures from the wellbore allow efficient coupling to the existing formation fracture network. Furthermore, these techniques allow for repeated stimulations allowing fractures to be extended further. Controlled rate pressurization is a useful tool for the efficient implementation of EGS. This multi-phase approach to fracturing can eliminate the need for massive pumping equipment and the water required with conventional hydraulic fracturing methods. Additionally these methods use “green” materials with negligible environmental impact. These methods promise to be more economical than conventional stimulation techniques. Our objective is to develop a family of ideal candidate energetic systems for optimally stimulating a formation.