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Title: Evaluation of Deep Subsurface Resistivity Imaging for Hydrofracture Monitoring

Abstract

This report describes the results of the first of its kind monitoring of a hydrofracture operation with electromagnetic measurements. The researchers teamed with oil and gas producer Encana Corporation to design and execute a borehole to surface monitoring of three fracture stages at a well pad in central Colorado. The field project consisted of an equipment upgrade, a survey design and modeling phase, several weeks of data collection, and data processing and interpretation. Existing Depth to Surface Resistivity (DSR) instrumentation was upgraded to allow for continuous high precision recording from downhole sources. The full system can now collect data continuously for up to 72 hours, which is sufficient to measure data for 10 frac stages. Next we used numerical modeling and frac treatment data supplied by Encana to design a field survey to detect EM signal from induced fractures. Prior to modeling we developed a novel technique for using well casing as an antenna for a downhole source. Modeling shows that 1) a measurable response for an induced fracture could be achieved if the facture fluid was of high salinity 2) an optimum fracture response is created when the primary source field is parallel to the well casing but perpendicularmore » to the fracture direction. In mid-July, 2014 we installed an array of more than 100 surface sensors, distributed above the treatment wells and extending for approximately 1 km north and 750 m eastward. We applied a 0.6 Hz square wave signal to a downhole current electrode located in a horizontal well 200 m offset from the treatment well with a return electrode on the surface. The data were transmitted to a recording trailer via Wi-Fi where we monitored receiver and transmitter channels continuously in a 72-hour period which covered 7 frac stages, three of which were high salinity. Although the background conditions were very noisy we were able to extract a clear signal from the high salinity stages. Initial data interpretation attempts consisting of trying to directly invert collected data using a simple background starting model did not produce reasonable models. We next used a simulated data set to develop a constrained inversion workflow that places the downhole fracture in the correct location. Finally, we used a combination of forward and inverse models to fit the collected data to a model that incorporated 3 frac stages. This project provided a first-of-its-kind application of EM technology to map an induced fracture. The results demonstrated a clear anomaly during the operation that can be fit to a reasonable model of an induced fracture.« less

Authors:
 [1];  [1]
  1. GroundMetrics, Inc., San Diego, CA (United States)
Publication Date:
Research Org.:
GroundMetrics, Inc., San Diego, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1333115
DOE Contract Number:
FE0013902
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 47 OTHER INSTRUMENTATION

Citation Formats

Hibbs, Andrew, and Wilt, Michael. Evaluation of Deep Subsurface Resistivity Imaging for Hydrofracture Monitoring. United States: N. p., 2016. Web. doi:10.2172/1333115.
Hibbs, Andrew, & Wilt, Michael. Evaluation of Deep Subsurface Resistivity Imaging for Hydrofracture Monitoring. United States. doi:10.2172/1333115.
Hibbs, Andrew, and Wilt, Michael. 2016. "Evaluation of Deep Subsurface Resistivity Imaging for Hydrofracture Monitoring". United States. doi:10.2172/1333115. https://www.osti.gov/servlets/purl/1333115.
@article{osti_1333115,
title = {Evaluation of Deep Subsurface Resistivity Imaging for Hydrofracture Monitoring},
author = {Hibbs, Andrew and Wilt, Michael},
abstractNote = {This report describes the results of the first of its kind monitoring of a hydrofracture operation with electromagnetic measurements. The researchers teamed with oil and gas producer Encana Corporation to design and execute a borehole to surface monitoring of three fracture stages at a well pad in central Colorado. The field project consisted of an equipment upgrade, a survey design and modeling phase, several weeks of data collection, and data processing and interpretation. Existing Depth to Surface Resistivity (DSR) instrumentation was upgraded to allow for continuous high precision recording from downhole sources. The full system can now collect data continuously for up to 72 hours, which is sufficient to measure data for 10 frac stages. Next we used numerical modeling and frac treatment data supplied by Encana to design a field survey to detect EM signal from induced fractures. Prior to modeling we developed a novel technique for using well casing as an antenna for a downhole source. Modeling shows that 1) a measurable response for an induced fracture could be achieved if the facture fluid was of high salinity 2) an optimum fracture response is created when the primary source field is parallel to the well casing but perpendicular to the fracture direction. In mid-July, 2014 we installed an array of more than 100 surface sensors, distributed above the treatment wells and extending for approximately 1 km north and 750 m eastward. We applied a 0.6 Hz square wave signal to a downhole current electrode located in a horizontal well 200 m offset from the treatment well with a return electrode on the surface. The data were transmitted to a recording trailer via Wi-Fi where we monitored receiver and transmitter channels continuously in a 72-hour period which covered 7 frac stages, three of which were high salinity. Although the background conditions were very noisy we were able to extract a clear signal from the high salinity stages. Initial data interpretation attempts consisting of trying to directly invert collected data using a simple background starting model did not produce reasonable models. We next used a simulated data set to develop a constrained inversion workflow that places the downhole fracture in the correct location. Finally, we used a combination of forward and inverse models to fit the collected data to a model that incorporated 3 frac stages. This project provided a first-of-its-kind application of EM technology to map an induced fracture. The results demonstrated a clear anomaly during the operation that can be fit to a reasonable model of an induced fracture.},
doi = {10.2172/1333115},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 9
}

Technical Report:

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  • 'This research is aimed at improving methods for characterizing underground contamination sites and for monitoring how they change with time. Particular emphasis is placed on identifying and quantifying the effects of intrinsic remediation and verifying the efficacy of engineered remediation activities. Isotopic measurements of elements such as C, O, H, He, Cl, and Sr, which are present in groundwater and soil gas, provide a quantitative measure of material balance. They can be used to identify the sites of origin of contaminants in groundwater, and to determine if contaminants are being destroyed as a result of natural processes or engineered processes.more » Isotope ratios also can be used to trace the migration of fluids that underground contaminants, such as steam and chemical reactions are occurring underground destruction of TCE usually produces carbon dissolution of calcite. are pumped down wells to destroy or confine grout, and they can be utilized to diagnose what and what materials are reacting. For example, dioxide, but carbon dioxide can also come from There are many isotopic ratios that can be measured in groundwater and vadose zone gas that could be valuable for characterizing remediation sites and monitoring remediation activities; The authors concentrate on a few that are particularly useful for the problems being addressed at the TAN (Test Area North) and RWMC (Radioactive Waste Management Complex) sites of the Idaho National Engineering Lab.. The isotopes the authors are using are {sup 13}C, {sup 14}C, {sup 3}He, {sup 87}Sr, {sup 37}Cl, and {sup 18}O.'« less
  • 'This research is aimed at improving methods for characterizing underground contamination sites and for monitoring how they change with time. Particular emphasis is placed on identifying and quantifying the effects of intrinsic remediation, and verifying the efficacy of engineered remediation activities. Isotopic measurements of elements like C, O, H, He, Cl, and Sr, which are present in groundwater and soil gas, provide a quantitative measure of material balance. They can be used to identify the sites of origin of contaminants in groundwater, and to determine if contaminants are being destroyed as a result of natural processes or engineered processes. Isotopemore » ratios can also be used to trace the migration of fluids that are pumped down wells to destroy or confine underground contaminants, such as steam and grout, and they can be used to diagnose what chemical reactions are occuring underground and what materials are reacting. For example, destruction of TCE usually produces carbon dioxide, but carbon dioxide can also come from dissolution of calcite. There are many isotopic ratios that can be measured in groundwater and vadose zone gas that could be valuable for characterizing remediation sites and monitoring remediation activities. The authors concentrate on a few that are particularly useful for the problems being addressed at the TAN (Test Area North) and RWMC (Radioactive Waste Management Complex) sites of the Idaho National Engineering Lab.. The isotopes the authors are using are carbon-13, carbon-14, helium-3, strontium-87, chlorine-37, and oxygen-18.'« less
  • The purpose of this project was to explore and refine applications of isotope measurements for guiding environmental remediation strategies. The isotopic compositions of samples from field sites were analyzed to address both basic scientific issues and site-specific problems. Initial efforts were concentrated on two sites at the Idaho National Engineering and Environmental Laboratory (INEEL). During the final year of the project, the focus of work was shifted to the Hanford site in Washington. The Test Area North (TAN) site at INEEL consists of a 2 km-long plume of mixed wastes containing low-level radionuclides, sewage and chlorinated solvents that were injectedmore » into the groundwater between 1955 and 1972. Isotopic measurements of groundwater samples were made to address questions about the source of the groundwater and the regional hydrology at TAN. These data show that there is a significant input to the groundwater from playa lakes that were located west of the TAN site prior to the 1950s (since that time, inflow to the playas has been diverted for agricultural uses). Radiocarbon dates of the playa waters indicate a mean infiltration rate of 3-5 cm/year. These results explain the groundwater flow patterns observed in the plume and provide constraints on transport rates.« less
  • The purpose of this project was to explore and refine applications of isotope ratio measurements for guiding environmental remediation strategies. The isotopic compositions of samples collected from field sites were analyzed to address both basic scientific issues and site-specific problems.
  • The Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, is operated for the U.S. Department of Energy (DOE) by Lockheed Martin Energy System (Energy Systems). ORNL has pioneered waste disposal technologies since World War II as part of its DOE mission. In the late 1950s, at the request of the National Academy of Sciences, efforts were made to develop a permanent disposal alternative to the surface and tanks at ORNL. One such technology, the hydrofracture process, involved inducing fractures in a geologic host formation (a low-permeability shale) at depths of up to 1100 ft and injecting a radioactive groutmore » slurry containing low-level liquid or tank sludge waste, cement, and other additives at an injection pressure of 2000 to 8500 psi. The objective of the effort was to develop a grout dig could be injected as a slurry and would solidify after injection, thereby entombing the radioisotopes contained in the low-level liquid or tank sludge waste. Four sites at ORNL were used: two experimental (HF-1 and HF-2); one developmental, later converted to batch process [Old Hydrofracture Facility (BF-3)]; and one production facility [New Hydrofracture Facility (BF-4)]. This document provides the environmental, restoration program with information about the the results of an evaluation of WAG 10 wells associated with the New Hydrofracture Facility at ORNL.« less