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Collaborating Authors
Results
Real-Time Monitoring of Fracture Dynamics with a Contrast Agent-Assisted Electromagnetic Method
Ahmadian, Mohsen (Bureau of Economic Geology, The University of Texas at Austin) | Haddad, Mahdi (Bureau of Economic Geology, The University of Texas at Austin) | Cui, Liangze (Duke University) | Kleinhammes, Alfred (University of North Carolina) | Doyle, Patrick (University of North Carolina) | Chen, Jeffrey (DIT, ESG Solutions) | Pugh, Trevor (DIT, ESG Solutions) | Liu, Qing Huo (Duke University) | Wu, Yue (University of North Carolina) | Mohajeri, Darwin (Bureau of Economic Geology, The University of Texas at Austin)
Abstract In collaboration with the Advanced Energy Consortium, our team has previously demonstrated that the placement of electrically active proppants (EAPs) in a hydraulic fracture surveyed by electromagnetic (EM) methods can enhance the imaging of the stimulated reservoir volumes during hydraulic fracturing. That work culminated in constructing a well-characterized EAP-filled fracture anomaly at the Devine field pilot site (DFPS). In subsequent laboratory studies, we observed that the electrical conductivity of our EAP correlates with changes in pressure, salinity, and flow. Thus, we postulated that the EAP could be used as an in-situ sensor for the remote monitoring of these changes in previously EAP-filled fractures. This paper presents our latest field data from the DFPS to demonstrate such correlations at an intermediate pilot scale. We conducted surface-based EM surveys during freshwater (200 ppm) and saltwater (2,500 ppm) slug injections while running surfaced-based EM surveys. Simultaneously, we measured the following: 1) bottomhole pressure and salinity in five monitoring wells; 2) injection rate using high-precision data loggers; 3) distributed acoustic sensors in four monitoring wells; and 4) tiltmeter data on the survey area. We demonstrated that injections into an EAP-filled fracture could be successfully coupled with real-time electric field measurements on the surface, leading to remote monitoring of dynamic changes within the EAP-filled fracture. Furthermore, by comparing the electrical field traces with the bottomhole pressure, flow rate, and salinity, we concluded that the observed electric field in our study is influenced by fracture dilation and flow rate. Salinity effect was observed when saltwater was injected. EM simulations solely based on assumptions of fracture conductivity changes during injection did not reproduce all of the measured electric field magnitudes. Preliminary estimates showed that including streaming potential in our geophysical model may be needed to reduce the simulation mismatch. The methods developed and demonstrated during this study will lead to a better understanding of the extent of fracture networks, formation stress states, fluid leakoff and invasion, characterizations of engineered fracture systems, and other applications where monitoring subsurface flow tracking is deemed important.
- North America > United States > Texas (0.47)
- Europe > United Kingdom > North Sea > Central North Sea (0.24)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (1.00)
- (2 more...)
Pressure Transient Analyses and Poroelastic Modeling of Hydraulic Fracture Dilation for Multiple Injections at the Devine Fracture Pilot Site
Haddad, Mahdi (Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin) | Ahmadian, Mohsen (Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin)
Abstract Our team has conducted electromagnetic (EM) surveys for the past six years to monitor hydraulic-fracture behavior at the Devine Fracture Pilot Site (DFPS). The sub-horizontal orientation of a shallow hydraulic fracture at the DFPS provides uniform access to the fracture area for interrogation and data collection. Ahmadian et al. (2023) suggested a possible correlation between spatiotemporal changes in the flow rate, bottomhole pressure (BHP), and the observed surface recorded electric field at the DFPS. In this paper, we present the development of poroelastic forward models and pressure transient analyses (PTAs) to support the development of a multiphysics inverse model for these EM surveys. First, we conducted PTAs of the shut-in periods after six injections out of 10 to determine the fracture closure pressure (FCP) or the overburden pressure used in a poroelastic fracture reopening model. Second, we developed a finite-element poroelastic model throughout five injection cycles to include the effect of the cumulative injected volumes due to the previous injections on current fracture dilation in the presence of highly permeable unpropped and propped zones adjacent to the cohesive layer that models fracture reopening. Fracture reopening in this poroelastic model is based on a calibrated traction-separation response using the bottomhole pressure collected in two injection campaigns in 2020 and 2022. We used the outcomes of a previous simulation study of the primary hydraulic-fracturing stimulation to define the dimension of an unpropped fracture zone ahead of the propped fracture area. The PTAs led to FCPs consistent with those obtained using the injection data collected at the DFPS in 2020. Further, these analyses showed that at later injections, the fracture closure occurred at a later time with respect to the shut-in time, inferring the effect of cumulative injected volumes in previous injections. The simulation results show that considering the propped and unpropped fracture zones improves our poroelastic model in predicting the injection-well BHP. The numerical simulation results demonstrate a significant excess pore pressure near the fracture because of the preceding formation loadings by the previous injections. The obtained fracture dilation area and fluid pressure distribution provide a basis to improve the development of a multiphysics inverse model. Furthermore, in an iteratively coupled scheme, this pressure distribution can be introduced into EM models to render a holistic view of the causative mechanisms for the surface signal anomalies.
- Research Report > New Finding (0.88)
- Research Report > Experimental Study (0.54)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics (0.87)
- South America > Argentina > Patagonia > Neuquรฉn > Neuquen Basin > Vaca Muerta Shale Formation (0.99)
- Africa > South Africa > Western Cape Province > Indian Ocean > Bredasdorp Basin > Block 9 > EM Field (0.99)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- (2 more...)
A series of images that look like yellow lumps on a line are the first-ever images of the area around the wellbore where fractures have been propped open using specially coated proppant stimulated by electromagnetic (EM) energy. The images created by Carbo Ceramics could represent a milestone on the journey to find an answer to a critical question facing unconventional producers--how much rock is being stimulated and propped with grains of sand or ceramic for maximum production? "People see the value in this area; they are starved for this," said Terry Palisch, global engineering adviser for Carbo, who described what is seen in the images as the propped reservoir volume. Four groups of researchers are seeking a direct way to visualize what is left behind after fracturing. Three of the projects involve getting images by using proppant specially treated to be visible when stimulated by EM energy. Microseismic images currently used in the industry to show fracturing results are based on the popping sounds of rocks rubbing against each other, like fingers snapping, but not the quiet, productive work of opening fractures and pumping in proppant to ensure they stay open.
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.49)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Texas > Permian Basin > Delaware Basin (0.99)
- (6 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (0.99)
Abstract This Permian Basin case study investigates the impact of primary (i.e., "parent") well depletion on infill (i.e., "child") well completions. The operator used electromagnetic frac fluid tracking to monitor the hydraulic fracturing treatments of three infill wells. The projectโs primary objectives centered on characterizing fracture-driven interference and understanding the impact of depletion on the new completions. Additionally, data were used to define fracture azimuths to help inform well spacing to improve development throughout the asset. A multidisciplinary team compared the frac fluid tracking results with offset parent well pressure data to better characterize the dynamic interaction between the treatment, geology and depletion caused by the primary wells. The three treatment wells, which targeted two different source rocks, were sandwiched between two producing parent wells to the east and three producing parent wells to the west. It was hypothesized that the five primary wells would likely create a large depleted reservoir volume surrounding them that would affect the hydraulic stimulations of the infill wells. To achieve the project objectives, the operator used electromagnetic (EM) frac fluid tracking combined with pressure data from two of the producing primary wells, one on either side (east and west). EM fluid tracking uses Controlled Source Electromagnetics (CSEM) technology to measure the changes in subsurface resistivity caused by treatment fluid injection. Injecting fracturing fluid into the source rock alters a generated EM field causing measurable differences from the surface and allows engineers to map the frac fluid movement over time. This technique involves a concert of disciplines from the electrical engineers that developed EM fluid tracking, to the geophysicists that process the results and interpret them with completion and reservoir engineers. The results can indicate when, where from, and to what extent the treatment fluid moves toward primary wells and depleted areas. The authors are experienced in monitoring infill well completions and observing fracture-driven interactions with primary wells. While the interpretation will be ongoing, the EM fluid tracking proved to be a valuable tool for observing fracture development and understanding reservoir dynamics, particularly in regard to the interaction of the hydraulic stimulations from the infill wells with pad-scale faulting and depletion caused by the parent wells.
- North America > United States > Texas (0.88)
- Africa > South Africa > Western Cape Province > Indian Ocean (0.24)
- Geology > Rock Type > Sedimentary Rock (0.71)
- Geology > Geological Subdiscipline > Geochemistry (0.46)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.46)
- Geology > Geological Subdiscipline > Geomechanics (0.46)
- Geophysics > Seismic Surveying (0.68)
- Geophysics > Electromagnetic Surveying (0.48)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (25 more...)
- Well Completion > Hydraulic Fracturing (1.00)
- Management > Asset and Portfolio Management > Field development optimization and planning (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.90)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (0.89)
Abstract This case study involves three infill (i.e., "child") wells drilled near a producing primary (i.e., "parent") well. All study wells target the same unconventional sandstone formation. The project objective is quantifying the interactions between the primary and infill wells. Such understanding will guide future development. The operator drilled five infill wells west of the primary well, two infill wells were drilled shallower than the three study wells. The primary well produced for seven months before the infill wellsโ completions. Of the three study wells, Well 3 is closest to the primary well. To mitigate interference from the infill wells, the operator 1) shut in the primary well during infill stimulation and 2) fractured the infill wells in an east-to-west "zipper" order, starting with Well 3. To monitor communication among the wells, the operator placed a bottom hole pressure gauge in the primary well and pumped fluid tracers in Wells 2 and 3. For an understanding of fracture geometry, the operator monitored the infill well stimulations with microseismic, which measures the acoustic response of fracturing, and electromagnetic (EM) fluid tracking. EM fluid tracking uses Controlled Source Electromagnetics (CSEM) technology to measure the changes in subsurface resistivity caused by treatment fluid injection. Injecting fracturing fluid into the source rock alters a generated EM field causing measurable differences on the surface. As a result, the technique maps fluid movement over time. These results highlight when treatment fluid preferentially develops toward the primary well. Introduction After drilling a primary well, deciding how to optimally develop the remainder of any given acreage can be a daunting challenge. Supported by theory and experience, each technical individual in a multi-disciplinary team has their own operational "secret sauce" to achieve the best results. As fields mature, operators developing unconventional basins drill a higher percentage of infill wells than primary wells and most of those wells are simply not as productive as the primary (Schaefer, 2019). Understanding what factors drive well performance is critical for operators to succeed in the current low-price environment. Testing different completion designs through a trail-and-error method and waiting for production results is neither efficient nor likely to yield conclusive results. Thus, operators must gather data during completions to measure fracture development and qualify design effectiveness. Without corroborating measurements, pressure gauges alone do not provide a complete picture of what occurs downhole during completions.
- North America > United States > Texas (0.94)
- Africa > South Africa > Western Cape Province > Indian Ocean (0.24)
- Geology > Geological Subdiscipline (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.56)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- (30 more...)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- (2 more...)
ABSTRACT Energized casing technology is increasingly used and studied for a variety of reservoir monitoring applications, e.g., waterflood monitoring, hydraulic fracture characterization, casing integrity mapping, due to its low cost and relatively easy deployment. The simultaneous presences of the thin casing structure and complex volumetric bodies, and their connections (i.e., wire-to-surface junction), as well as the layered background formation in the field scale, make the accurate modeling of the subsurface sensing applications a tough computation challenge. Numerical methods based on the differential equation, such as the finite difference method and finite element method, show difficulties in mesh generation and heavy computation burden. Another widely used forward simulation method, i.e., integral equation method (IEM) which employs simple discretizations on the casing, the junction, and the body surface, is developed to simulate the subsurface sensing applications. A canonical example and numerical example of hydraulic fracture monitoring are studied. The simulations demonstrate that the IEM scheme is efficient to model the wire-to-surface structures in layered media. It also shows that this scheme can be adapted to model complex structures connected to the casing in the deep subsurface. Presentation Date: Tuesday, September 17, 2019 Session Start Time: 8:30 AM Presentation Time: 11:25 AM Location: 225C Presentation Type: Oral
- North America > United States > Texas > Anadarko Basin (0.99)
- North America > United States > Oklahoma > Anadarko Basin (0.99)
- North America > United States > Kansas > Anadarko Basin (0.99)
- Africa > South Africa > Western Cape Province > Indian Ocean > Bredasdorp Basin > Block 9 > EM Field (0.99)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (0.68)
ABSTRACT We present a simulation of the electromagnetic (EM) response and its joint interpretation with fracking monitoring simulation during hydraulic fracturing in an unconventional reservoir. A multiphysics workflow is presented, using a criterion based on a breakdown pressure to generate and propagate the hydraulic fracturing, where both pressure response and EM response were jointly constructed. The approximate solution of Maxwell equations was obtained using a mixed Finite Element Method (FEM) combined with Leapfrog time stepping procedure. The spatial discretization of Maxwell equations is achieved using the mixed finite-element spaces of Nedelec where the electrical field have continuous tangential component across the edges of the computational mesh. Leapfrog time stepping was used for the time discretization, so that the fully discrete sequence is first solving for the electric field using Preconditioned Conjugate Gradient Iteration (PCGI) and then solving for the magnetic field. A stability analysis of this FEM method was performed. The results show that the EM response might be sensitive enough to be monitored and the magnetic field correlates better with the saturation distribution than the electric field. Furthermore, due to its relation to water saturation and effective connectivity, it is shown that EM monitoring yields additional information to determine the Stimulated Reservoir Volume (SRV). An error analysis of estimations from EM and the actual saturation size indicates that the petrophysical assumption is perhaps the most sensitive part of this study. Presentation Date: Tuesday, September 17, 2019 Session Start Time: 8:30 AM Presentation Time: 9:20 AM Location: 225C Presentation Type: Oral
- South America > Argentina > Patagonia > Neuquรฉn > Neuquen Basin > Vaca Muerta Shale Formation (0.99)
- Oceania > Australia > South Australia > Cooper Basin (0.99)
- Oceania > Australia > Queensland > Cooper Basin (0.99)
- Africa > South Africa > Western Cape Province > Indian Ocean > Bredasdorp Basin > Block 9 > EM Field (0.99)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- (2 more...)
Summary The onset of the era of internet of things and artificial intelligence comes with the ever-growing demand for self-sustaining and efficient sensors. Sensors based on complementary metal oxide semiconductors (CMOSs) have attracted significant attention in the implementation of distributed sensor systems for a vast number of applications because of their economical and complex integration benefits. In this work, we report CMOS-based energy-harvesting chips as wireless nodes for mapping hydraulic fractures during the shale gas extraction process. The CMOS chips are tested in a custom benchtop core-holder chamber that emulates a downhole environment. An induction coil, sized at 5โรโ5โmm, connected to a custom CMOS chip, is used as a receiver inside the core holder to harvest electromagnetic (EM) energy transmitted by an external antenna. On the basis of the custom core-holder experiment, it is shown that encapsulated CMOS chips are able to harvest EM energy and thereby operate wirelessly. The receiver has a resonance frequency of 198 MHz. The CMOS chip is equipped with an integrated power management unit (PMU), energy-harvesting unit, and a signal-generation block. The CMOS chip inside the chamber produces an output signal with a frequency proportional to the harvested power. By measuring the frequency of the output signal produced by the chip, we are able to localize the chips within the rock inside the custom core holder.
- Asia > Middle East (0.93)
- North America > United States > California (0.30)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (0.60)
Abstract We have developed a simulation of the electromagnetic (EM) response and its joint interpretation with fracking monitoring simulation during hydraulic fracturing in an unconventional reservoir. A multiphysics workflow is presented, using a criterion based on a breakdown pressure to generate and propagate the hydraulic fracturing, where the pressure response and EM response were jointly constructed. The approximate solution of Maxwell equations was obtained using a mixed finite-element method (FEM) combined with a leapfrog time-stepping procedure. The spatial discretization of the Maxwellโs equations is achieved using the mixed finite-element spaces of Nedelec, in which the electrical fields have a continuous tangential component across the edges of the computational mesh. Leapfrog time stepping was used for the time discretization, so that the fully discrete sequence is first solving for the electric field using preconditioned conjugate gradient iteration and then solving for the magnetic field. A stability analysis of this FEM method is provided. The results indicate that the EM response might be sensitive enough to be monitored and the magnetic field correlates better with the saturation distribution than the electric field. Furthermore, due to its relation to water saturation and effective connectivity, it is shown that EM monitoring yields additional information to determine the stimulated reservoir volume. An error analysis of estimations from EM and the actual saturation size indicates that the petrophysical assumption is perhaps the most sensitive part of this study.
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
Abstract Miniaturized transponder systems for mapping hydraulic fractures, monitoring unconventional reservoirs and measuring other wellbore parameters are under development. These devices, called FracBots (Fracture Robots), are envisioned as an extension of RFID (Radio Frequency IDentifcation) tags to realize Wireless Underground Sensor Networks (WUSNs) for mapping and characterization of hydraulic fractures in unconventional reservoirs. When injected during hydraulic fracturing operations, autonomous localization algorithms could be used to build up 3D constellation maps of proppant bed placement. To explore this concept, a FracBot prototype platform was developed, with which three key functions have been demonstrated, and are here reported. First, we developed a novel cross-layer communication framework for Magnetic Induction (MI) -based FracBot networks in dynamically changing underground environments, combining joint selection of modulation, channel coding and power control, a transmitter-based CDMA scheme and a geographic forwarding paradigm. Second, we developed a novel MI-based localization framework which exploits the unique properties of the MI field to determine the locations of the randomly deployed FracBot nodes. Third, we developed an accurate energy model framework for a linear FracBot network topology that gives feasible FracBots' transmission rates and FracBot network topology while respecting harvested energy constraints. Future work will include design and fabrication of miniaturized MI-based FracBot nodes for evaluation in a physical WUSN testbed.
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (0.71)
- Data Science & Engineering Analytics > Information Management and Systems > Artificial intelligence (0.66)
- Information Technology > Artificial Intelligence (1.00)
- Information Technology > Communications > Networks > Sensor Networks (0.91)