Southeast Regional Carbon Sequestration Partnership Research Articles

Transport of perfluorocarbon tracers in the Cranfield Geological Carbon Sequestration Project

AbstractA field‐scale carbon dioxide (CO2) injection pilot project was conducted by the Southeast Regional Carbon Sequestration Partnership (SECARB) at Cranfield, Mississippi. Two associated campaigns in 2009 and 2010 were carried out to co‐inject perfluorocarbon tracers (PFTs) and sulfur hexafluoride (SF6) with CO2. Tracers in gas samples from two observation wells were analyzed to construct breakthrough curves. In this work, we present the field data and numerical modeling of the flow and transport of CO2, brine, and tracers. A high‐resolution static model of the formation geology in the detailed area study (DAS) was used to capture the impact of connected flow pathways created by fluvial channels on breakthrough curves and breakthrough times of PFTs and SF6 tracers. We use the cubic‐plus‐association (CPA) equation of state, which takes into account the polar nature of water molecules, to describe the phase behavior of CO2–brine‐tracer mixtures. Our simulated results show good agreement for the 2009 tracer campaign in Cranfield, while a larger discrepancy emerges by 2010. The combination of multiple tracer injection pulses with detailed numerical simulations proves to be a powerful tool in constraining both formation properties and how complex flow paths develop over time. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

Effects of CO2 on mechanical variability and constitutive behavior of the Lower Tuscaloosa Formation, Cranfield Injection Site, USA

We characterize geomechanical constitutive behavior of reservoir sandstones at conditions simulating the “Cranfield” Southeast Regional Carbon Sequestration Partnership injection program. From two cores of Lower Tuscaloosa Formation, three sandstone lithofacies were identified for mechanical testing based on permeability and lithology. These include: chlorite-cemented conglomeratic sandstone (Facies A); quartz-cemented fine sandstone (Facies B); and quartz- and calcite-cemented very fine sandstone (Facies C). We performed a suite of compression tests for each lithofacies at 100°C and pore pressure of 30MPa, including hydrostatic compression and triaxial tests at several confining pressures. Plugs were saturated with supercritical CO2-saturated brine.Chemical environment affected the mechanical response of all three lithofacies, which experience initial plastic yielding at stresses far below estimated in situ stress. Measured elastic moduli degradation defines a secondary yield surface coinciding with in situ stress for Facies B and C. Facies A shows measurable volumetric creep strain and a failure envelope below estimates of in situ stress, linked to damage of chlorite cements by acidic pore solutions. The substantial weakening of a particular lithofacies by CO2 demonstrates a possible chemical-mechanical coupling during injection at Cranfield with implications for CO2 injection, reservoir permeability stimulation, and enhanced oil recovery.

Comparison of geochemical data obtained using four brine sampling methods at the SECARB Phase III Anthropogenic Test CO2 injection site, Citronelle Oil Field, Alabama

The chemical composition of formation water and associated gases from the lower Cretaceous Paluxy Formation was determined using four different sampling methods at a characterization well in the Citronelle Oil Field, Alabama, as part of the Southeast Regional Carbon Sequestration Partnership (SECARB) Phase III Anthropogenic Test, which is an integrated carbon capture and storage project. In this study, formation water and gas samples were obtained from well D-9-8 #2 at Citronelle using gas lift, electric submersible pump, U-tube, and a downhole vacuum sampler (VS) and subjected to both field and laboratory analyses. Field chemical analyses included electrical conductivity, dissolved sulfide concentration, alkalinity, and pH; laboratory analyses included major, minor and trace elements, dissolved carbon, volatile fatty acids, free and dissolved gas species. The formation water obtained from this well is a Na–Ca–Cl-type brine with a salinity of about 200,000mg/L total dissolved solids. Differences were evident between sampling methodologies, particularly in pH, Fe and alkalinity. There was little gas in samples, and gas composition results were strongly influenced by sampling methods. The results of the comparison demonstrate the difficulty and importance of preserving volatile analytes in samples, with the VS and U-tube system performing most favorably in this aspect.

Field testing of modular borehole monitoring with simultaneous distributed acoustic sensing and geophone vertical seismic profiles at Citronelle, Alabama

ABSTRACTA modular borehole monitoring concept has been implemented to provide a suite of well‐based monitoring tools that can be deployed cost effectively in a flexible and robust package. The initial modular borehole monitoring system was deployed as part of a CO2 injection test operated by the Southeast Regional Carbon Sequestration Partnership near Citronelle, Alabama. The Citronelle modular monitoring system transmits electrical power and signals, fibre‐optic light pulses, and fluids between the surface and a reservoir. Additionally, a separate multi‐conductor tubing‐encapsulated line was used for borehole geophones, including a specialized clamp for casing clamping with tubing deployment. The deployment of geophones and fibre‐optic cables allowed comparison testing of distributed acoustic sensing. We designed a large source effort (>64 sweeps per source point) to test fibre‐optic vertical seismic profile and acquired data in 2013. The native measurement in the specific distributed acoustic sensing unit used (an iDAS from Silixa Ltd) is described as a localized strain rate. Following a processing flow of adaptive noise reduction and rebalancing the signal to dimensionless strain, improvement from repeated stacking of the source was observed. Conversion of the rebalanced strain signal to equivalent velocity units, via a scaling by local apparent velocity, allows quantitative comparison of distributed acoustic sensing and geophone data in units of velocity. We see a very good match of uncorrelated time series in both amplitude and phase, demonstrating that velocity‐converted distributed acoustic sensing data can be analyzed equivalent to vertical geophones. We show that distributed acoustic sensing data, when averaged over an interval comparable to typical geophone spacing, can obtain signal‐to‐noise ratios of 18 dB to 24 dB below clamped geophones, a result that is variable with noise spectral amplitude because the noise characteristics are not identical. With vertical seismic profile processing, we demonstrate the effectiveness of downgoing deconvolution from the large spatial sampling of distributed acoustic sensing data, along with improved upgoing reflection quality. We conclude that the extra source effort currently needed for tubing‐deployed distributed acoustic sensing vertical seismic profile, as part of a modular monitoring system, is well compensated by the extra spatial sampling and lower deployment cost as compared with conventional borehole geophones.

Monitoring CO2 Storage at Cranfield, Mississippi with Time-Lapse Offset VSP – Using Integration and Modeling to Reduce Uncertainty

Abstract A time-lapse Offset Vertical Seismic Profile (OVSP) data set was acquired as part of a subsurface monitoring program for geologic sequestration of CO2. The storage site at Cranfield, near Natchez, Mississippi, is part of a detailed area study (DAS) site for geologic carbon sequestration operated by the U.S. Dept. of Energy's Southeast Regional Carbon Sequestration Partnership (SECARB). The DAS site includes three boreholes, an injection well and two monitoring wells. The project team selected the DAS site to examine CO2 sequestration multiphase fluid flow and pressure at the interwell scale in a brine reservoir. The time-lapse (TL) OVSP was part of an integrated monitoring program that included well logs, crosswell seismic, electrical resistance tomography and 4D surface seismic. The goals of the OVSP were to detect the CO2 induced change in seismic response, give information about the spatial distribution of CO2 near the injection well and to help tie the high-resolution borehole monitoring to the 4D surface data. The VSP data were acquired in well CFU 31-F1, which is the ∼3200 m deep CO2 injection well at the DAS site. A preinjection survey was recorded in late 2009 with injection beginning in December 2009, and a post injection survey was conducted in Nov 2010 following injection of about 250 kT of CO2. The sensor array for both surveys was a 50-level, 3-component, Sercel MaxiWave system with 15 m (49 ft) spacing between levels. The source for both surveys was an accelerated weight drop, with different source trucks used for the two surveys. Consistent time-lapse processing was applied to both data sets. Time-lapse processing generated difference corridor stacks to investigate CO2 induced reflection amplitude changes from each source point. Corridor stacks were used for amplitude analysis to maximize the signal-to-noise ratio (S/N) for each shot point. Spatial variation in reflectivity (used to ‘map’ the plume) was similar in magnitude to the corridor stacks but, due to relatively lower S/N, the results were less consistent and more sensitive to processing and therefore are not presented. We examined the overall time-lapse repeatability of the OVSP data using three methods, the NRMS and Predictability (Pred) measures of Kragh and Christie (2002) and the signal-to-distortion ratio (SDR) method of Cantillo (2011) . Because time-lapse noise was comparable to the observed change, multiple methods were used to analyze data reliability. The reflections from the top and base reservoir were identified on the corridor stacks by correlation with a synthetic response generated from the well logs. A consistent change in the corridor stack amplitudes from pre- to post-CO2 injection was found for both the top and base reservoir reflections on all ten shot locations analyzed. In addition to the well-log synthetic response, a finite-difference elastic wave propagation model was built based on rock/fluid properties obtained from well logs, with CO2 induced changes guided by time-lapse crosswell seismic tomography ( Ajo-Franklin et al., 2013 ) acquired at the DAS site. Time-lapse seismic tomography indicated that two reservoir zones were affected by the flood. The modeling established that interpretation of the VSP trough and peak event amplitudes as reflectivity from the top and bottom of reservoir is appropriate even with possible tuning effects. Importantly, this top/base change gives confidence in an interpretation that these changes arise from within the reservoir, not from bounding lithology. The modeled time-lapse change and the observed field data change from 10 shotpoints are in agreement for both magnitude and polarity of amplitude change for top and base of reservoir. Therefore, we conclude the stored CO2 has been successfully detected and, furthermore, the observed seismic reflection change can be applied to Cranfield's 4D surface seismic for spatially delineating the CO2/brine interface.

Project Assessment and Evaluation of the Area of Review (AoR) at the Citronelle SECARB Phase III Site, Alabama USA

Abstract The Southeast Regional Carbon Sequestration Partnership (SECARB) Anthropogenic Test is a demonstration of the deployment of CO 2 capture, transport, geologic storage and monitoring technologies. This project is the first and the largest fully integrated commercial prototype coal-fired carbon capture and storage projects in the USA. The demonstration has reached the 100,000 metric ton (tonnes) injection milestone and is in the second year of injection operations. Two Class V Experimental Injection Well underground injection control (UIC)

Near-Surface Monitoring of Large-Volume CO2 Injection at Cranfield: Early Field Test of SECARB Phase III

Summary An early field project of the Southeast Regional Carbon Sequestration Partnership (SECARB) was conducted in Cranfield oil field, western Mississippi. Carbon dioxide (CO2) was injected into coarse-grained fluvial deposits of the Cretaceous lower Tuscaloosa formation, forming a gentle anticline at depths of 3300 m. CO2 injection started in July 2008, increasing to 23 wells (as of May 2011), with total injection rates greater than 1 million tons/yr. Focused monitoring programs of the deep subsurface and near surface have been implemented in different study areas. Here we present results of the near-surface monitoring program over a 3-year period, including shallow groundwater monitoring and soil-gas monitoring. A general methodology of detecting CO2 leakage into shallow groundwater chemistry is proposed. A set of geochemical indicator parameters was identified on the basis of the characterization of groundwater geochemistry, and these were further tested and validated using numerical modeling approaches, laboratory experiments, and field experiments. For soil-gas monitoring, a site (P-site) containing a plugged and abandoned well, a nearby open pit, and an engineered pad (representing a typical industrial near-surface environment for soil-gas monitoring) was selected for detailed study. The site was heavily instrumented with various sensors for measuring soil-gas concentrations at different depths, soil-water content, matric potential, and weather information. Three monitoring technologies were assessed: soil CO2 concentration measurements, CO2 flux measurements on the land surface, and multiple soil-gas component measurements. Results indicate that soil-gas-component measurements provide reliable information for gas-leakage detection. Methodologies of near-surface monitoring developed in this study can be used to improve CO2-leakage monitoring at other CO2 sequestration projects. This early field project was funded by the US Department of Energy, National Energy Technology Laboratory, as part of the Regional Carbon Sequestration Partnerships (RCSP) program. SECARB is led by the Southern States Energy Board (SSEB).

Project Status and Research Plans of 500 TPD CO2 Capture and Sequestration Demonstration at Alabama Power's Plant Barry

Southern Company and Mitsubishi Heavy Industries Ltd. (MHI) successfully started the world's largest (500 metric TPD) carbon capture plant MHI's KM-CDR® on a coal-fired power plant in June 2011 at Alabama Power's Plant Barry. The captured CO2 is transported via pipeline approximately 12 miles to Citronelle oil field where it is injected into the Paluxy formation, a saline reservoir, for storage. This part of the CCS demonstration project is the DOE funded Southeast Regional Carbon Sequestration Partnership (SECARB) phase III Anthropogenic Test. This paper will include the status and results to date of this demonstration project along with research plans associated with the 500 TPD CO2 capture facility.

The SECARB Anthropogenic Test: Status from the Field

The United States Department of Energy (DOE) seeks to validate the feasibility of injecting, storing and monitoring CO2 in the subsurface (geologic storage) as an approach to mitigate atmospheric emissions of CO2. In an effort to promote the development of a framework and the infrastructure necessary for the validation and deployment of carbon sequestration technologies, DOE established seven Regional Carbon Sequestration Partnerships (RCSPs). The Southeast Regional Carbon Sequestration Partnership (SECARB), whose lead organization is the Southern States Energy Board (SSEB), represents 13 States within the south eastern United States of America (USA).The SECARB Anthropogenic Test R&D project is a demonstration of the deployment of CO2 capture, transport, geologic storage and monitoring technology. This project is an integral component of a plan by Southern Company, and its subsidiary, Alabama Power, to demonstrate integrated CO2 capture, transport and storage technology. The capture component of the test takes place at the James M. Barry Electric Generating Plant (Plant Barry) in Bucks, Alabama utilizing capture technology licensed by Mitsubishi Heavy Industries America (MHIA). The capture facility, equivalent to 25 megawatts (MW), will utilize post-combustion amine capture technology licensed by Mitsubishi Heavy Industries America. CO2 captured at the plant will be transported by pipeline for underground storage in a deep, saline geologic formation within the Citronelle Dome located in Citronelle, Alabama.Starting in the third quarter of 2012, up to 550 metric tonnes of CO2 per day, the equivalent emissions from 25 MW of the plant's capacity have been captured for geologic storage. The injection target is the lower Cretaceous Paluxy formation which occurs at a depth of 2,865 meters (9,400 feet). Transportation and injection operations will continue for one to two years. Subsurface monitoring will be deployed through 2017 to track plume movement and monitor for leakage. This project will be one of the first and the largest fully-integrated commercial prototype coal-fired carbon capture and storage projects in the USA. This paper will discuss the results to date, including permitting efforts, baseline geologic analysis and detailed reservoir modeling of the storage site, framing the discussion in terms of the overall goals of the project.

Reservoir characterization and complications for trapping mechanisms at Cranfield CO2 injection site

Understanding and predicting physical and chemical trapping mechanisms are important for designing successful CO2 storage projects. The processes have been investigated extensively by numerical modeling and, to a lesser degree, by laboratory experiments. The results of modeling and laboratory studies need to be verified at field conditions and scales. A variety of field data sets have been collected at the Cranfield CO2 injection and monitoring site of the Southeast Regional Carbon Sequestration Partnership (SECARB) where 3.54 million tons of CO2 had been injected by February 2012. Field characterization and extensive monitoring provide unique insights into the trapping processes that help in immobilizing injected CO2. The four-way closure of the injection zone ensures effective structural trapping of buoyant CO2 and maximum opportunity for chemical trapping. The fluvial reservoir shows a high degree of lithologic and petrophysical heterogeneity associated with multiple episodes of fluvial-channel incision and deposition. Variable diagenetic chlorite further exerts a complex overprint on rock properties because chlorite grain coatings prevent quartz cementation and preserve porosity. CO2 solubility in the brine under the field condition is approximately 36g/L (9kg/m3 rock volume). The CO2–brine contact area is maximized within the sinuous and focused flow pathways that could increase dissolution. Yet geochemical reactions are found to be very slow in the reservoir. Mineral trapping capacity is limited because the reservoir rocks contain only trace amount of reactive minerals that supply cations to convert CO2 into carbonate minerals. Two parallel multiphase flow experiments show that CO2 residual saturation varies significantly between conglomerate and sandstone (31% and 3.5%) facies in the reservoir, which complicates estimates of residual trapping capacity.

Seal evaluation and confinement screening criteria for beneficial carbon dioxide storage with enhanced coal bed methane recovery in the Pocahontas Basin, Virginia

The geological storage of carbon dioxide in Appalachian basin coal seams is one possible sink for sequestration of greenhouse gases, with the added benefit of enhanced-coal bed methane (ECBM) recovery. The Pocahontas Basin (part of the central Appalachian Basin) of southwestern Virginia is a major coal bed methane (CBM) province with production mostly from coal beds in the Lower Pennsylvanian Pocahontas and New River formations. As part of the Southeast Regional Carbon Sequestration Partnership's Phase II research program, a CO2-injection demonstration well was installed into Lower Pennsylvanian coal bed-methane producing strata in southwest Virginia. Samples of siliciclastic lithologies above coal beds in this Oakwood Field well, and from several other cores in the Nora Field were taken to establish a baseline of the basic confinement properties of overlying strata to test seal competency at local and regional scales. Strata above CBM-producing coal beds in the Pocahontas and New River formations consist of dark-gray shales; silty gray shales; heterolithic siltstones, sandstones, and shales; lithic sandstones, and quartzose sandstones. Standard measurements of porosity, permeability and petrography were used to evaluate potential leakage hazards and any possible secondary storage potential for typical lithologies. Both lithic- and quartz-rich sandstones exhibit only minor porosity, with generally low permeability (< 0.042 mD). Interconnected porosity and permeability are strongly impacted by diverse cementation types and compaction. Analyzed siliciclastic lithologies are considered tight, with limited primary matrix permeability risks for leakage, providing an ensemble of redundant CO2-ECBM traps. One of the most promising confining intervals above the major coal bed-methane producing interval is the Hensley Shale Member. Analyses of 1500 geophysical logs in southwest Virginia indicate that this unit is moderately thick (> 50 ft, 15 m), laterally continuous (> 3000 km2), and a homogenous shale, which coarsens upward into siltstone and sandstone, or is truncated by sandstone. Calculations from two mercury injection capillary porosimetry tests of the shale indicate that a displacement entry pressure of 207 psi (1427 kPa) would generate an estimated seal capacity of 1365 ft (416 m) of CO2 before buoyant leakage. Scanning electron microscopy indicates a microfabric of narrow pore throats between quartz grains floating in a clay matrix. Modeled median pore throat size between micro-fabric matrix grains for the shale is estimated at 0.26 μm. These characteristics indicate that the shale, where fractures and joints are limited, would be an adequate regional confining interval for deeper CO2 storage with ECBM.

Monitoring a large volume CO2 injection: Year two results from SECARB project at Denbury’s Cranfield, Mississippi, USA

The Southeast Regional Carbon Sequestration Partnership (SECARB) early project in western Mississippi has been testing monitoring tools and approaches to document storage efficiency and storage permanence under conditions of CO2 EOR as well as downdip injection into brine. Denbury Onshore LLC is host for the study and has brought a depleted oil and gas reservoir, Cranfield Field, under CO2 flood. Injection was started in July 2008 and has now achieved injection rates greater than 1.2 million tons/year though 23 wells, with cumulative mass injected as of August, 2010 of 2.2 million metric tons. Injection is into coarse grained fluvial deposits of the Cretaceous lower Tuscaloosa Formation in a gentle anticline at depths of 3300 m. A team of researchers from 10 institutions has collected data from five study areas, each with a different goal and different spatial and temporal scale. The Phase 2 study began at the start of injection and has been using pressure and temperature as a tool for assessing permanence mostly in the oil productive interval. Real-time read-out shows high sensitivity to distant changes in injection rate and confirms the geologic model of reservoir compartmentalization. Above-zone pressure monitoring ∼120 m above the injection interval is used to test the sensitivity of this approach for documentation of integrity of the confining system in an area of numerous well completions as pressure increase is induced in the reservoir by more than 70 bar. Monitoring of the High Volume Injection Test (HiVIT) area includes repeat measurements of aqueous geochemistry in the injection zone. Rock-water- CO2 interactions in the reservoir as CO2 dissolves are minimized by mineral “armoring” by abundant chlorite cement in high permeability reservoir sandstone. Geochemical monitoring of confined freshwater aquifers at depths of 70–100 m is underway. Groundwater analysis focuses on assessment of the sensitivity of this method to detect leakage above background variability. A repeat seismic survey of the HiVIT is planned for late 2010 to assess saturation change especially in downdip brine-only areas. A study focused on feasibility of monitoring the shallow subsurface to separate leakage from normal complex surface fluxes is underway at an monitoring array installed in October 2009 to assess the interactions of recharge, soil gas, and shallow groundwater aquifers. Recent well re-entry and tracer injection will provide further information to interpret observed elevated deep-sourced methane. The Detailed Area Study (DAS) is collecting dense time-lapse data from closely-spaced three well array of an injector and two observation wells. The observation wells were completed with fiberglass casing to facilitate electrical resistance tomography (ERT) measurements, and a diverse array of instrumentation was both cemented behind casing and suspended on tubing. Injection started at the DAS December 1, 2009. We have measured pulsed neutron and resistivity via wireline, downhole and above-zone pressure, distributed temperature, and fluid chemistry including introduced pulses of perfluorocarbons, noble gases, and SF6 as tracers. Between wells, time-lapse crosswell seismic and electrical resistance tomography (ERT) are used to measure saturation change. The goals are to measure changes as fluids evolve from single phase (brine) to two phase (CO2–brine) in order to document linkages between pressure and sweep efficiency. A time-lapse VSP survey bridges the vertical resolution and areal coverage between cross-well and surface seismic. The repeat surveys for many tools are scheduled for September, 2010. Reservoir characterization based on cores, historic and new wireline log data, production history, hydrologic tests, fluid analysis, and a three-D seismic survey have been used in multiple numerical models to predict reservoir response in order to design effective monitoring strategies and optimize deployment. History matching of observed response to predicted response is used to interpret results and improve confidence in conceptual models and numerical approaches. Probabilistic methods have been used to assess the significant uncertainties resulting from reservoir heterogeneity. This study is funded by the US Department of Energy, National Energy Technology Laboratory as part of the Regional Carbon Sequestration Partnerships program. SECARB is led by Southern States Energy Board.

Large‐scale carbon sequestration

The U.S. Department of Energy (DOE) announced on 9 October the first three large‐scale carbon sequestration projects in the United States. The three projects Plains Carbon Dioxide Reduction Partnership, Southeast Regional Carbon Sequestration Partnership, and Southwest Regional Partnership for Carbon Sequestration double the number of large‐volume carbon storage demonstrations in operation worldwide. DOE plans to invest $197 million over 10 years, subject to annual appropriations from Congress, for the projects, which are the first of several sequestration demonstration projects planned through DOE's Regional Carbon Sequestration Partnerships.