A Water Working Group (WWG) was formed by the Regional Carbon Sequestration Partnerships (RCSPs) of the U.S. Department of Energy (DOE) in 2009 to identify and address the water-related challenges associated with the commercial deployment of carbon capture and storage (CCS) in the United States. The WWG, which consists of a team of experts from government, academia, and industry, initiated its efforts with the preparation of a white paper on the nexus of CCS and water, which was published in January 2010. This white paper summarized the CCS processes and technologies that affect water usage, described the types of water that exist in deep formations targeted for storage, and described the potential impacts of CO2 storage on existing formation fluids as well as potable water resources. The treatment technologies that may be applied to water produced from these deep formations during CO2 storage were also addressed, including opportunities to utilize this water, as is or following treatment, as a resource for beneficial reuse. This initial effort was followed by a technology gap assessment workshop (2011) and a stakeholder survey (2012). The results of the former identified gaps for a number of technical challenges created by the CCS–water nexus while the latter identified both technical and nontechnical topics that were of particular concern to a variety of CCS stakeholders. Broadly speaking, the topics of most concern to the CCS stakeholders were the technical and economic challenges associated with the capture of CO2 and the potential impacts to water resources, followed closely by the mitigation of potential water impacts. The WWG then proceeded to conduct a mixture of stakeholder and technical outreach activities that were focused on facilitating the transfer of previous research as well as spurring the conduct of future research that targeted these water-related challenges, opportunities, and concerns.

The PCOR Partnership Program’s CO2 utilization and storage research has evolved/matured over the past 15 years, including the creation of an adaptive management approach specific to carbon capture, utilization, and storage (CCUS). The program’s myriad of achievements can be attributed to showing that CCUS is a technically viable carbon management approach and that CO2 enhanced oil recovery processes can be efficiently monitored to verify safe, permanent associated storage of millions of tonnes of CO2. These achievements instill public awareness and trust so important to future CCUS projects.

The EERC teamed with the DOE National Energy Technology Laboratory to conduct complementary research and development under the Joint Program on Research and Development for Fossil Energy-Related Resources (Cooperative Agreement No. DE-FC26-08NT43291). This 10-year program merged two previous 10-year agreements—DE-FC26-98FT40320 and DE-FC26-98FT40321—into a single follow-on agreement. The Fossil Energy cooperative agreement between DOE and the EERC was initiated in 1983 when the EERC was defederalized. This dynamic 35-year partnership has evolved to further research in areas that address DOE Office of Fossil Energy program goals while serving the missions and exploiting the strengths of both organizations through this agreement and a new 5-year Fossil Energy-Related Resources cooperative agreement established in 2015. As the 10-year program has ended, the purpose of this report is to summarize the activity and significant outcomes that were accomplished by the EERC. This program is an excellent model for research, development, demonstration, and commercialization partnerships between government, industry, and the applied science and engineering communities to bring cutting-edge science closer to commercial application. The overarching goal was to support DOE Fossil Energy goals by advancing the scientific knowledge and technical development essential to ensuring future sustainable supplies of affordable energy and clean water, protecting and restoring the environment, and reducing dependence on foreign energy sources, thereby increasing U.S. energy security. The strategic objective was to advance continued use of domestic fossil fuels as a mainstay of U.S. energy production by making fossil energy systems nonpolluting and more efficient, capturing and sequestering greenhouse gases, and integrating the use of fossil and renewable energy sources into the energy mix. The research achievements from this partnership have exceeded the goals and objectives by contributing substantially to the development of science-based energy and environmental policy, educational foundations for science and technology, and commercialization and international marketing of energy technologies. The program comprised 75 individual projects, which included basic/applied fossil energy research projects involving no cost share and development, demonstration, and commercialization projects (many derived from applied research projects) that included nonfederal cost share of approximately 40% (the contractually required minimum level of cumulative nonfederal cost share was 29%). In all, 32,798,698 of federal funding was leveraged with industry cash and in-kind cost share of 21,697,129 from 80 nonfederal partners for a total of 54,495,827 of funded research that 1) advanced the development of unconventional tight oil resources in the Bakken Formation; 2) demonstrated the application of CO2 Storage and EOR in tight oil formations; 3) developed advanced carbon capture technology; 4) addressed key application and infrastructure concerns for commercial deployment of CO2; 5) demonstrated innovative, integrated water management strategies for energy development projects; 6) developed novel pollution control technologies for mercury and hazardous air pollutants; and 7) performed world-class outreach and dissemination of research results to industry partners and other stakeholders. These outcomes speak to the valuable return on the substantial investment in this program.

Abstract Oil production grew significantly from 0.2 million barrels per day (bpd) to 1.1 million bpd in the Bakken petroleum system from 2009 to 2014. A large volume of associated gas (1.6 billion cubic feet per day) has also been produced with the oil. A substantial part (>10%) of this produced gas is flared off because of the low natural gas price and limited infrastructure for gathering and transporting the gas from the well sites. Such a large scale of gas flaring not only wastes energy but also emits contaminants such as SOx, NOx, and CO2 to the atmosphere. Reduction of flaring and utilization of produced gas are important steps toward sustained development of the Bakken. The potential for recycled gas enhanced oil recovery (EOR) is being investigated as a method of reducing flaring through utilization. However, large-scale gas flooding might be difficult for the Bakken because of the difference between the low-permeability matrix and the highly conductive hydraulic and natural fracture networks, which may lead to low sweep efficiency. Instead, this research by the Energy & Environmental Research Center (EERC) has aimed to investigate, through a series of laboratory experiments and numerical simulation activities, the potential to extract oil from the tight rocks by taking advantage of diffusion-based processes. Oil and gas produced from Bakken wells were characterized, and the reservoir formation properties were analyzed based upon core samples. A series of oil extraction experiments with varying gas (solvent) compositions were conducted. The minimum miscibility pressure (MMP) of various produced gas components and oil was measured to determine the pressure required for effective extraction. Based on the experimental results, a well-scale model was developed to simulate the performance of recycled gas EOR. Results showed CO2 and produced Bakken gas to be miscible with the oil in reservoir conditions (>5000 psi, 230°F). The measured MMPs for pure CO2 and ethane with typical Bakken oil samples were 2528 and 1344 psi, respectively. The presence of methane in the gas increased MMP, but miscibility was still achievable under reservoir conditions. CO2 and ethane enabled extraction of most oil components from the rocks during a 24-hour experimental period, but methane exhibited strong molecular selectivity for light-end components. Simulation results showed that a single-well CO2 and methane/ethane huff ‘n’ puff operation could increase cumulative oil production as much as 50% for the multistage fractured wells in the Bakken. The results of this study clearly showed that produced Bakken gas could be effectively used for recycled gas EOR. Implementation of EOR may have potential to compensate for the production decline of Bakken wells while reducing the quantity of flared gas.

The purpose of this best practices manual (BPM) is to describe lessons learned and best practices for site characterization of carbon dioxide (CO2) geologic storage (herein “storage”) projects. Information presented is derived from field and laboratory storage project activities conducted by the Plains CO2 Reduction (PCOR) Partnership. Site characterization is one of four technical elements of the adaptive management approach (AMA) formalized by the PCOR Partnership for storage project development. The other technical elements are modeling and simulation; risk assessment; and monitoring, verification, and accounting (MVA) of injected CO2 .

Summary Compared with a conventional reservoir, the ultralow permeability in the Bakken Formation makes it very challenging to perform normal waterflooding or gasflooding operations. “Permeability-jail” effects cause low injectivity and prevent injected fluids from sweeping oil out of the matrix efficiently. Two distinguishable flow regimes have been identified in fractured, hydrocarbon-rich shale formations: viscous flow in high-permeability fracture networks and diffusion-dominated flow in the low-permeability matrix with high oil saturation. Improving hydrocarbon transport (and technically recoverable resources) in unconventional reservoirs relies on our ability to enhance diffusion-dominated flow from the oil-saturated matrix to the natural- or induced-fracture network, which is the focus of this study. To unlock the unproduced Bakken and Three Forks oil, high-pressure carbon dioxide (CO2) may be used to enhance the diffusion-dominated flow in the matrix and keep the viscous flow in the fractures under reservoir temperature and pressure conditions (e.g., 230°F and 5,000 psi). Core samples were collected from two Bakken wells, including all oil-bearing intervals: Upper Bakken (UB), Middle Bakken (MB), and Lower Bakken (LB) Members and the Three Forks (TF) Formation. Detailed core analyses were performed to measure petrophysical properties and characterize these units. Ten samples were selected for pore-size-distribution measurement and 21 samples (11-mm-diameter rods) were used for 24-hour CO2 exposures and hydrocarbon-recovery experiments. These experiments were conducted as CO2 “bathing” at reservoir conditions (rather than “flow through” tests) and were aimed at increasing our understanding of the microstructure and diffusion-dominated-flow ability within these tight geologic formations. CO2-exposure and hydrocarbon-extraction experimental results clearly showed the improvement of diffusion-dominated flow in all the Bakken members. The UB and LB samples, characterized by generally high total-organic-carbon (TOC) content (10–15 wt%) and small pore size (approximately 3–7 nm), yielded approximately 60% of the present mature hydrocarbon at the end of the 24-hour exposure. The MB and TF samples, characterized by lower TOC content (<0.5 wt.%) and moderate pore size (approximately 8–80 nm), provided more-favorable flow conditions for CO2 and hydrocarbons, yielding approximately 90% of the mature-hydrocarbon content. Because all experiments were conducted at reservoir conditions, the results demonstrate that diffusion plays a significant role in the mobilization of oil in tight reservoirs. CO2 greatly enhances the diffusion process to improve hydrocarbon transport in the tight matrix. This observation is especially useful for densely fractured shale-oil formations (high surface-area/volume ratio) where CO2 has greater areal contact with the reservoir, enabling CO2 diffusion into the matrix and hydrocarbon diffusion out of the matrix to occur more efficiently (increasing recoverable reserves), and where the fracture networks assist in alleviating potential injectivity challenges.

The effects of reservoir temperature and percent levels of methane and ethane in CO2 on the minimum miscibility pressures (MMPs) of crude oils were measured using a vanishing interfacial tension (VIT) method. MMPs increased linearly with methane concentrations but decreased when ethane was added to CO2. Higher reservoir temperatures yielded much higher MMPs for the same oil, apparently because of the reduction in CO2 densities that occur with increasing temperature. Oil samples collected from the CO2-dominated mobile “miscible” phase demonstrated that higher pressures mobilized more oil regardless of MMP, and that CO2 preferentially mobilizes lighter hydrocarbons, especially at lower pressures.

Abstract Enhanced oil recovery (EOR) processes using CO2 in tight unconventional plays like the Bakken Formation are expected to be very different from the processes which control EOR in conventional reservoirs. During CO2 EOR in conventional reservoirs, CO2 flows through the permeable rock, and the minimum miscibility pressure (MMP) is an important operational parameter for achieving a successful "miscible" flood. In contrast, in tight fractured systems like the Bakken, CO2 flow may be dominated by fracture flow, and not by CO2 flowing through the rock matrix as in a conventional reservoir flood. Since fracture-dominated CO2 flow could essentially eliminate the "flushing" mechanisms responsible for increased recovery in conventional reservoirs, operation at or slightly above MMP may or may not be relevant for the success of an EOR flood in such tight fractured reservoirs. To investigate this concept, capillary-rise vanishing interfacial tension (VIT) was used to measure MMP values for a typical Bakken crude oil (API gravity 41.5) with CO2, methane, and ethane at 110°C (230°F) typical for the reservoir. The effect of these different fluids, as well as the effect of pressures at, above, and well above MMP on recovering crude oil hydrocarbons was determined for small rock core samples from the productive Middle Bakken laminated zone as well as from Upper and Lower Bakken samples. Compared to the MMP value for CO2 of 2520 psi, MMP with methane nearly doubled at 4510 psi, but was nearly cut in 1/2 for ethane at 1360 psi. The recovery of crude oil hydrocarbons from both the Middle Bakken and Lower Bakken shale samples with 24-hour exposures to these fluids at reservoir pressures showed efficiencies that parallel the MMPs determined with each fluid; i.e., ethane yielded faster and more efficient recovery of the crude oil than CO2, but both CO2 and ethane were much more efficient than methane at recovering the crude oil from the 11-mm round rod rock samples. Although hydrocarbon recoveries from the rock samples paralleled each injectant's respective MMP values, extractions with CO2 at the MMP, and at ca. double and triple the MMP pressure showed much more efficient crude oil recoveries at higher pressures from both the Middle Bakken and Lower Bakken shale, demonstrating that EOR pressures much higher than the MMP could substantially increase oil recoveries in tight unconventional systems like the Bakken.

Abstract Over 40 rock samples were obtained from six Bakken wells which penetrate through the major oil pay including two shale intervals: Upper and Lower Bakken, and two tight intervals that are the targets for drilling: Middle Bakken and Three Forks. Detailed petrographic and petrophysical analyses were performed on the samples to better correlate the extraction results with the physical and geochemical properties of the rocks. Round rods (11.2-mm diameter X ca. 30–40 mm long) drilled from each of the 40 samples were individually exposed in a "bath" of CO2 for 24 hours at reservoir temperature and pressure of 5000 psi and 230°F (34.5 MPa, 110°C), and the recovered crude oil hydrocarbons were collected periodically and analyzed to determine the rates and efficiencies of oil recovery. For the 26 Middle Bakken and Three Forks rocks, hydrocarbon recovery upon CO2 exposure averaged 86% after 7 hours, and 99% after 24 hours. Recoveries of the crude oil (not including kerogen) from the 15 Upper and Lower shales were surprisingly high with an average of 30% recovered after 7 hours, and 50% recovered after 24 hours. While the Middle Bakken and Three Forks TOC values were ca. 0.3 wt.% (similar to their crude oil content), TOCs for the Upper and Lower Bakken shales were typically 10 to 15 wt.%, with ca. one-tenth of that organic content being crude oil hydrocarbons as opposed to kerogen. The Upper and Lower shales also had significantly smaller pore throat sizes (averaging ca. 3 nm) than the Middle Bakken and Three Forks samples (which averaged ca. 10–26 nm). Additional studies are being performed to determine whether the small pore throat sizes (which approach molecular dimensions) and/or the sorption of crude oil hydrocarbons onto the kerogen in the Upper and Lower shales are responsible for the slower hydrocarbon recovery than that achieved from the Middle Bakken and Three Forks rocks under CO2 exposure. Currently, the main targets for horizontal drilling are Middle Bakken and Three Forks, where thousands of multistage hydraulically fractured wells have been drilled in the past decade. The high oil recovery factor observed in cores from these intervals, especially when compared to the 7% average recovery in the field, indicates the huge potential for oil recovery factor improvement in these units by increasing oil production based upon supercritical CO2 extraction.

Although well logs and core data show that there is significant oil content in Bakken shales, the oil transport behavior in these source rocks is still not well understood. This lack of understanding impedes the drilling and production operations in the shale members. A series of experiments were conducted to investigate the rock properties of the Bakken shales and how to extract oil from the shales using supercritical CO2. High-pressure mercury injection tests showed that pore throat radii are less than 10 nm for most pores in both the upper and lower Bakken samples. Such small pore sizes yield high capillary pressure in the rock and make fluid flow difficult. Total organic carbon content was measured using 180 shale samples, and kerogen was characterized by Rock-Eval pyrolysis, which indicated considerable organic carbon present (10-15 wt%) in the shales. However, oil and gas are difficult to mobilize from organic matter using conventional methods. A systematic experimental procedure was carried out to reveal the potential for extracting hydrocarbons from the shale samples using supercritical CO2 under typical Bakken reservoir conditions (e.g., 34.5 MPa and 110 degrees C). Results showed that supercritical CO2 enables extraction of a considerable portion (15-65%) of hydrocarbons from the Bakken shales within 24 h. Measurement of CO2 adsorption isotherm showed that Bakken shale has a considerable capability to trap CO2 (up to 17 mg/g) under a wide range of pressures. The experimental results suggest the possibility of using supercritical CO2 injection to increase the ultimate oil recovery and store a considerable quantity of CO2 in the Bakken Formation.

The Energy & Environmental Research Center (EERC) has recently completed 7 years of research through the Cooperative Agreement with the U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) focused on fossil energy technology development and demonstration. To support a significant number of the different activities being considered within all of our research contracts with NETL, a subtask (6.1 – Strategic Studies) was created to focus on small research efforts that came up throughout the year that would support an existing EERC–NETL project or would help to develop a new concept for inclusion in future efforts. This subtask was funded through the EERC–DOE Joint Program on Research and Development for Fossil Energy-Related Resources Cooperative Agreement No. DE-FC26- 08NT43291

The feasibility of a carbon capture and storage (CCS) project at the Fort Nelson Gas Plant in British Columbia, Canada, has been conducted. The feasibility study included the collection of baseline characterization data, static and dynamic modelling efforts, two rounds of risk assessment, and the development of a draft monitoring, verification, and accounting (MVA) plan. Those activities have been compared to the Canadian Standards Association (CSA) standard for geologic storage of carbon dioxide. Although the remote location, difficult terrain, and extreme climate of the potential injection site make MVA challenging, cost- effective MVA that meets or surpasses the CSA standards is achievable.