Michael Wilt | Lawrence Berkeley National Laboratory (original) (raw)

Papers by Michael Wilt

Cymric oil field frequency domain electromagnetic (FEM) data with two parts of data labeled Part ... more Cymric oil field frequency domain electromagnetic (FEM) data with two parts of data labeled Part 1 and Part 2. Part 1 utilizes an electrical source line parallel to the receiver line, while Part 2 utilizes an electrical source line at a 75 deg angle to the receiver line. Data are plotted and compared to numerically modeled data to observe electric field response to well structure. In two configuration files are diagrams of the experiment layout.

$Research paper thumbnail of Using well casing as an electrical source to monitor hydraulic fracture fluid injection$

The depth to surface resistivity (DSR) method transmits current from a source located in a cased ... more The depth to surface resistivity (DSR) method transmits current from a source located in a cased or openhole well to a distant surface return electrode while electric field measurements are made at the surface over the target of interest. This paper presents both numerical modelling results and measured data from a hydraulic fracturing field test where conductive water was injected into a resistive shale reservoir during a hydraulic fracturing operation. Modelling experiments show that anomalies due to hydraulic fracturing are small but measureable with highly sensitive sensor technology. The field measurements confirm the model results, showing that measured differences in the surface fields due to hydraulic fracturing have been detected above the noise floor. Our results show that the DSR method is sensitive to the injection of frac fluids; they are detectable above the noise floor in a commercially active hydraulic fracturing operation, and therfore this method can be used for mo...

GEOPHYSICS, 2021

Well integrity is one of the major concerns in long-term geologic storage sites due to the potent... more Well integrity is one of the major concerns in long-term geologic storage sites due to the potential risk of well leakage and groundwater contamination. Evaluating changes in electrical responses due to energized steel-cased wells has the potential to quantify and predict possible wellbore failures because any kind of breakage or corrosion along highly conductive well casings will have an impact on the distribution of the subsurface electrical potential. However, realistic wellbore-geoelectrical models that can fully capture fine-scale details of well completion design and the state of well damage at the field scale require extensive computational effort, or they can even be intractable to simulate. To overcome this computational burden while still keeping the model realistic, we have used the hierarchical finite-element method that represents electrical conductivity at each dimensional component (1D edges, 2D planes, and 3D cells) of a tetrahedral mesh. This allows well completion ...

SEG Technical Program Expanded Abstracts 2018, 2018

Subsurface Sensing Technologies and Applications II, 2000

This paper presents recent advances and case histories of two non-traditional electromagnetic geo... more This paper presents recent advances and case histories of two non-traditional electromagnetic geophysical techniques for oil reservoir characterization, and production/process monitoring. The crosswell electromagnetic induction method has seen rapid advancement since its inception in the early 1990's, and to this date numerous surveys have been completed in active oil fields as well as other sites. Here one example is given where a 2D electrical conductivity image derived from crosswell data is employed for reservoir characterization, and two other examples presented where the method provided valuable insight into the 2- and 3-D progress of water flood operations. The second, less mature method discussed involves 3-D imaging from multi-component induction log data. Here all three components of the magnetic field generated by a single or multiple sources are inverted to produce estimates of the electrical conductivity distribution surrounding the borehole. For this technology an example is given of three component data acquisition in an active oil field, as well as a proof of the 3-D imaging concept on a synthetic data set.

Journal of Zhejiang University-SCIENCE A, 2005

Wellbore integrity is of paramount importance to subsurface resource extraction, energy storage a... more Wellbore integrity is of paramount importance to subsurface resource extraction, energy storage and waste disposal. After installation, well casing and cement are subject to mechanical stress due to near-well pressure changes and fluid induced corrosion. This is exacerbated for geothermal wells where produced fluid is at high temperature and corrosive. The current state-of-the-art technologies for wellbore integrity assessments are an array of cased hole logging tools. Wireline deployed acoustic, electromagnetic and mechanical tools are all available to inspect steel casing corrosion and casing-cement bond and these tools can provide high-resolution assessment of borehole conditions. They are intrusive, however, in terms of borehole preparation and interruption to the normal operation of the wells, and not suitable for high temperature or highly deviated well deployments. In addition, these measurements are performed infrequently due to high cost, and are therefore incapable of prov...

Injection of CO2 into the subsurface at industrial-scale can result in significant fluid pressure... more Injection of CO2 into the subsurface at industrial-scale can result in significant fluid pressure increases in the reservoir that if not properly controlled, can lead to potential environmental impacts such as fault activation, leakage through abandoned wells, or caprock fracturing. Brine extraction is one approach for managing formation pressure, effective stress, and plume movement in response to CO2 injection. The management of the extracted brine has a cost that is added to carbon capture and sequestration operations, and therefore minimizing the extraction volume of brine is of great importance. This work presents an integrated adaptive management approach involving monitoring, model calibration, and optimization of brine extraction for pressure control. Knowledge of the subsurface properties is always incomplete, and especially during the planning stages of CO2 projects, very little is known because of often quite limited site characterization data and related uncertainties. T...

SSRN Electronic Journal, 2019

SPE Annual Technical Conference and Exhibition, 2018

Casing integrity is a major issue for thousands of older oil and water wells. Damage to well casi... more Casing integrity is a major issue for thousands of older oil and water wells. Damage to well casings may occur for multiple reasons, including corrosive wellbore fluids, mechanical failures, or external forces, and can lead to impaired production and environmental risks. We propose a rapid, non-invasive electromagnetic (EM) method for diagnostic testing of casing integrity. The well casing is energized by connecting an electrical current source at low frequency to the wellhead. Current flows down the casing and out into the formation at a rate defined by the length of the casing, the casing conductance, and the formation resistivity. Damaged casing has a reduced conductance, and so the flow of current is altered, with an increased amount leaving the casing above the damaged segment. This affects the electric fields observed at the surface, a difference which can be measured with sufficiently sensitive electric field sensors. By comparing forward modeling results based on wellbore di...

Symposium on the Application of Geophysics to Engineering and Environmental Problems 1995, 1995

Borehole-to-surface electromagnetic (EM) methods are an attractive alternative to Surface-based E... more Borehole-to-surface electromagnetic (EM) methods are an attractive alternative to Surface-based EM methods for a variety of environmental and engineering applications. They have improved sensitivity to the subsurface resistivity distribution because of the closer proximity to the area of interest offered by the borehole for the source or the receiver. For the borehole-to-surface measurements the source is in the borehole and the receivers are on the surface. On the other hand, for the surface-to-borehole methods, the source is on the surface and the receiver is in a borehole. The surface-to-borehole method has an added advantage since measurements are often more accurate due to the lower noise environment for the receiver. For these methods, the source can be a grounded electric dipole or a vertical magnetic dipole source. An added benefit of these techniques is field measurements are made using a variety of arrays where the system is tailored to the application and where one can take advantage of some new imaging methods. In this short paper the authors describe the application of the borehole-to-surface method, discuss benefits and shortcomings, and give two field examples where they have been used for underground imaging. The examples were the monitoring of a salt watermore » flooding of an oil well and the characterization of a fuel oil spill.« less

The Leading Edge, 1989

Engineering geophysics has long played a role in geotechnical site investigations, although the s... more Engineering geophysics has long played a role in geotechnical site investigations, although the significance and acceptance of the results have varied considerably. There has been a tremendous surge in acceptance and applications of engineering geophysics within the past 10 years. This improved status has resulted from a number of factors, not the least of which are improved instrumentation and microcomputers, better trained personnel, and the recognition of classes of geotechnical problems for which engineering geophysics is not only ideally suited but in many cases the only viable option. One such class of problems is the investigation of existing structures and their foundations, such as earth and rockfill dams. This class of problems has emerged in the United States, for example, because of an aging and decaying infrastructure; the key words in this effort are evaluation, repair, maintenance, and rehabilitation. Remediation efforts are directed to increasing the useful life of structures and insuring ...