The goal of this two-year research project is to utilize a pressure/salinity responsive electrically active proppant (EAP) to characterize hydrological response of fracture network in simulated production conditions. The project seeks to develop an approach to remotely monitor changes in pressure and/or salinity within the fractured network in near real time. The methods developed and demonstrated during this study will lead to a better understanding of the extent of proppant-filled fracture networks, formation stress states, fluid leak offs and invasions, and characterizations of engineered fracture systems.
Bureau of Economic Geology (BEG) at the University of Texas at Austin - Austin, TX 78759
Because induced fracture networks’ propped zones are generally very thin (commonly less than 5 mm) they are difficult to detect and delineate at depth. Hydraulic Fracturing (HF) has evolved to a sophisticated multi-step process with varying flow rates, carrier fluids (gel or slick water), proppant loadings, and proppant grain sizes. Current tools, such as micro-seismic and tiltmeter monitoring, can provide information on fracture extent but provide little or no information on the movement and final distribution of proppant or production fluids. Recovery from HF reservoir is often a small fraction of the original oil in place (ranging often to less than 10–20% ultimate recovery from tight unconventional reservoirs). As stated in the FOA1990: “Part of this problem is due to the inability of current well completion processes to effectively stimulate the entire reservoir area contacted by the wellbore. Innovative technologies are needed that can help improve the effectiveness of reservoir completion methods, maximize stimulated reservoir volume and optimize recovery over a well’s entire producing life.”
Previous work by BEG has resulted in a set of validated electromagnetic (EM) codes to interrogate HF extent remotely by EM geophysics. Based on those results, an updated multi-scale, multi-mode forward and inversion approach will be developed. Lab studies will be carried out to characterize the impact of salinity/pressure on EAP’s properties. This information along with host rock properties will be used as input for solvers to discern feasibility of detection and will inform design of optimal EM and seismic survey configurations for successful demonstration of the concept. Once sensitivity of detection has been demonstrated in year 1, field survey work be conducted at the BEG’s Devine Field Pilot Site (DFPS) in year 2.
The resulting techniques yield more efficient production of hydraulically fractured reservoirs. The unique and comprehensive data sets collected in this study will be disseminated to the public and will lay the foundation for the advancement of additional geophysical fracture mapping and modeling techniques.
The project was awarded on October 1, 2019.
Teams have been assembled and are working on the following tasks over the next 6 months:
Preparing a comprehensive lithology and depositional environment report based on the available cores from DFPS.
Building an impedance analysis cell for the benchtop electrical measurements of the EAP under variable salinity and pressure condition which will be used as input for performing EM sensitivity analysis to ensure detectability at field scale.
Utilizing available velocity parameters from DFPS cores to perform sensitivity analysis for various seismic scenarios.
Working on choosing the best analytical solution for near real-time EM inversions, including the traditional voxel-based approach vs neural network approach. We will further test the robustness of our EM inversion solver with some synthetic data and EM field data under the DFPS configuration.
Performing fluid flow modeling with available reservoir properties, simulating for several different fluid injection scenarios for the field injection and preparing for future field activities at DFPS.