The goal of this project is to develop a water management decision support system by modifying and integrating a state-of-the art water resource simulation model with a modern enterprise geographic information system, which will provide a science-based tool to support development of energy resources in the Fayetteville Shale region.
University of Arkansas, Fayetteville, Arkansas
Texas A&M University, Temple, Texas
Argonne National Laboratory, Argonne, Illinois
It is generally recognized that activities related to oil and natural gas exploration, drilling, completion, and production affect surface and ground water resources to some degree. Water availability, due to significant use of water for the fracturing process and the consequent disposal of wastes, along with potential impairment of water quality, is a primary concern. In the Fayetteville Shale play, the combined demands on water resources for public and agricultural uses and for natural gas production could be significant.
Natural gas-shale activities are expected to increase in the near future and a substantial body of literature has provided evidence that water supply related issues have the potential to be a major limiting factor in the growth of shale gas development. Water resources are affected by numerous competing factors, such as water demand for agriculture and human consumption, along with potential changes in supply levels brought about by processes such as drought and changing climate.
While specific issues are framed by the existing knowledge base, there is currently a lack of science-based informational and operational support systems and strategies addressing the combined areas of drilling and hydrology. These structures are needed to help the gas industry and regulatory agencies manage these water resource and water management issues. The lack of such strategies impairs the implementation of reliable regional and basin-oriented shale gas development plans to support regulatory streamlining and permitting.
The proposed project will provide information to the public and industry regarding water issues, and will develop and implement quantitative tools for visualization and water management. Providing an open and transparent accounting of the water supplies will allow shale development by providing updated estimates of surface water availability while reducing potential adverse impacts associated with water usage for fracturing the shale.
The results of this research are expected to significantly advance knowledge of how ground and surface water withdrawal (primarily for hydraulic fracture, but with the addition of public and agricultural use taken into account) affects water availability and quality in a watershed—particularly in the Fayetteville Shale Play. For example, an accurate map of all surface water (meaning retention ponds and small water bodies) covering a very large area will be made available, and the effect of this usually unaccounted for water can be estimated. This could have a direct and immediate impact on natural gas producers who are considering the use of retention ponds as a source of “frac” water.
The deliverables of this project will directly impact the public in the form of well-organized information at the intersection of gas-shale development and water use, and producers and regulators who will be able to immediately share extensive, model-driven information about the effects of the development decisions they make.
The soil and water assessment tool (SWAT), developed by the University of Arkansas’s Center for Advanced Spatial Technology (CAST), is being utilized to model surface water availability for four large watersheds and 75 sub-basins in Arkansas. Modeled results will help the ANRC predict physical availability of surface water and allocation levels during times of shortage. Modeled flow rates can be used by ANRC during the water withdrawal permitting process to make better informed decisions about withdrawal volumes, duration, and timing. Dr. Cothren and CAST are actively involved in the Water Supply Availability Working Group led by Ken Brazil of the ANRC. Results from this project will be instrumental in addressing surface water withdrawal permit sections of the Arkansas Water Plan.
Researchers have received feedback on their modeled results to help them make the model more accurate at the smaller watershed level. University of Arkansas and TAMU researchers are conducting additional testing and are further developing the model.
Dr. Cothren continues to meet with Ken Brazil of the ANRC who plans to use the tool as part of the water permitting approval process in the future. Previous project results have shown that water withdrawals for oil and gas production do not have an impact on the overall watershed, but smaller-scale flows, such as streams and creeks that lead to the rivers, can be affected. Researchers are refining the tool in order to reflect the smaller-scale results. The ANRC has provided researchers with the state water withdrawal records from 2010 to present.
A manuscript entitled “Evaluation of Environmental Flow Components in the Fayetteville Shale Area” was submitted to the journal Oil and Gas Science and Technology on June 29, 2012.
The researchers have modeled the impact of hydraulic fracturing water withdrawals on the Little Red watershed. Preliminary results show that individual withdrawals have very little impact, but collective withdrawals could impact watersheds at certain low flow conditions. Dr. Cothren continues to work with the state to develop the FSDSS decision tools that will aid in watershed modeling related to shale gas activities on a sub-basin level. There is concern about aquatic communities being affected by low flow conditions.
Water withdrawal volumes from three watersheds were modeled using the Soil and Water Assessment Tool (SWAT) and compared to Arkansas Natural Resources Commission (ANRC) data for the years 2008 and 2009. Results suggest water was trucked in during 2008 while more impoundments were utilized in 2009. Modeling for the years 2010–2015 will be used to assess the potential impact of increasing hydraulic fracturing activity on the state’s hydrology. A graphic environmental flow component has been developed to visualize the changes from high to low flows within a watershed over time. The ANRC finds these graphics very helpful, and they could be used to identify problems in low flow areas.
Researchers met with ANRC regulators to discuss using the modeling tools for the state water diversion permitting process. Current permits allow users to withdraw approved water volumes at any time during the year. With the recent simulations showing that critical low flows could be reached with significant simultaneous withdrawals, the researchers hope to better predict the water balance results at the smaller watershed levels where the impact could be greater. The Arkansas state water diversion plan is over thirty years old and does not address many current issues. With better tools, low flow conditions could be better predicted by the ANRC.
The SWAT model was calibrated and validated for five chosen watersheds. Low flow conditions were predicted when extreme withdrawal and low precipitation events were modeled. Further simulation and validation tasks will be delayed 3–5 months. The percentage of yearly stream discharge used for hydraulic fracturing was calculated from 0.01 to 1.11 percent for seven watersheds. SWAT modeling of a sub-watershed with high HF water withdrawals during low flow conditions showed some critical flow events, which could result in damaging effects to river ecology.
Researchers gave a presentation on the current hydrology simulation results and improved management issues in the Fayetteville Shale area at the 2011 IPEC Conference.
Project personnel met with the United States Geological Survey (USGS) to discuss obtaining missing stream gauge data. The team is also gathering PRISM rainfall data to supplement NEXRAD data. Real-time and near real-time rainfall data will be available in the Fayetteville Shale Decision Support System (FSDSS) to help predict water flow into the watersheds. Meetings continue with Ken Brazil from the ANRC, who plans to use the model to aid in approving water withdrawal permits. Models are not currently being used by the ANRC for permitting. Researchers are calibrating hydraulic unit code to be more sensitive to water withdrawals on a smaller scale in watersheds. The project team is also calculating drainage areas for retention ponds, with more complex flow models and erosion processes, which will enhance the current run-off models used in the FSDSS. Argonne National Laboratory researchers have begun to identify state and federal water regulatory requirements, which will be added to the existing Fayetteville Shale Information Website. Argonne will also outline the methods currently being used to obtain and transport water for use in hydraulic fracturing and for disposing or reusing the flowback water.
The research team met with the ANRC to discuss the development of interactive tools that could be used during water permit evaluations to increase the efficiency of the permit process and provide more accurate data. Researchers and the ANRC are collaborating on model testing, stream gauge calibration, reservoir outflow and agricultural management practices. A direct data link to current and historical USGS stream gauge data has been established in the FSDSS, while links to National Weather Service precipitation data and NEXRAD weather radar data are being developed.
The University of Arkansas hosted the Environmentally Friendly Drilling Systems Workshop on November 16, 2010. Water issues in the Fayetteville Shale Play were discussed. The agenda and presentations are available at https://www.uark.edu/ [external site].
Relevant technologies and updated regulations impacting surface water in the Fayetteville shale play have been researched and the data incorporated into the existing FSDSS website. Researchers have collaborated with the ANRC to identify specific regulatory and permitting issues, including surface water withdrawals and use. The Fayetteville Shale Information Site (FSIS) public map viewer has been updated to show the number of active, inactive, and permitted wells related to natural gas drilling activities by watershed. Updates offer a greatly enhanced user interface and historical production values aggregated to production units. The updates have received positive feedback from stakeholders.
Stream gauge records, daily weather records, and climate data were collected from the USGS and the National Weather Service. This information, along with GIS data layers, was converted for use in the watershed case studies for the SWAT simulations. The updated FSIS site has received positive feedback from stakeholders regarding the updates to surface water and permitting activities within watersheds.
Other previously developed GIS data layers (DEM, hydrography, land use/land cover, soil and geology formation maps) were processed for use in the watershed case studies. Three representative case studies to study the effects of oil and gas operations on the stream flow within the Fayetteville Shale area using the SWAT model have been identified. The case study locations were chosen based on biophysical settings and availability of historical stream flow records, and represent diverse hydrologic characteristics.
The team’s automated mapping of small water bodies identified significantly more surface water than was previously found in national datasets. The small water body layer will play an important role in the FSDSS by determining how much water is retained in a watershed, and its development is expected to influence ANRC's surface water diversion permit decisions. Object oriented imagery analysis has been used to locate and characterize retention ponds by using high-resolution, color-infrared aerial imagery of the entire Fayetteville Shale area. Data processing began and drainage areas for each retention pond were computed. The newly developed layer is able to capture the true shape, size, and location of the ponds. The results are seen as an improvement to the existing hydrology dataset.
The project ended on June 30, 2013. The final report is listed below under "Additional Information".