Frio brine sequestration pilot in the Texas Gulf Coast

A field experiment to pioneer CO2 injection for sequestration in a brine-bearing sandstone-shale sequence in the Texas Gulf Coast, USA, is in the preinjection modeling and planning phase. Innovations in this experiment include (1) CO2 injection into high-volume highpermeability rocks that have storage capacity sufficient to impact greenhouse gas emissions, (2) injection into a setting lacking the complications introduced by hydrocarbons and perturbations resulting from production and secondary recovery, and (3) intensive pre-, syn-, and post-injection monitoring and modeling for validation of the effectiveness of sequestration. The experiment is designed to provide a rapid increase in information from a small-volume and short-duration injection.Bureau of Economic Geolog

EOR as sequestration: Geoscience perspective

CO2 Enhanced Oil Recovery (EOR) has a development and operational history several decades longer than geologic sequestration of CO2 designed to benefit the atmosphere and provides much of the experience on which confidence in the newer technology is based. With modest increases in surveillance and accounting, future CO2 EOR using anthropogenic CO2 (CO2-A) captured to decrease atmospheric emissions can be used as part of a sequestration program.Bureau of Economic Geolog

Carbon Capture and Geologic Sequestration from Intermittent Use of Fossil Fuels

Essentially all scenarios for reducing greenhouse gas emissions require deployment of a portfolio of mechanisms. In this paper, I consider the interactions among different emissions reductions methods focusing on how much flexibility in source-sink matching and intermittent operation is possible in Carbon capture and sequestration (CCS) methods. CCS is one of the mechanisms proposed to mitigate CO2 released from stationary sources. Much of the previous evaluation has focused on electricity generation from traditional base-load power plants, especially those that use coal as an energy source. This is reasonable for several reasons: flue gas from coal combustion has high CO2 concentrations, making post-combustion capture more efficient; coal has relatively high CO2 emissions per unit of energy, so that mitigation is needed; gasifiers and other chemical processes are widely used on coal, providing concentrated CO2 stream; and coal interest groups have organized programs to build “clean coal” programs in many regions. Coal has been widely used a base load power, with electricity from gas deployed as peak load. Planning a capture system to run as continuously as possible lowers cost per ton abated and per kilowatt generated and a stable system reduces design complexity and risk. However, shifting energy systems show that the assumption that CCS will be applied to base load coal power may be limited, and more complex scenarios are needed. In US markets low prices for natural gas have caused a shift from coal to natural gas. A system designed to reduce overall emissions by shifting dispatch away from the most carbon intensive facilities, such as the US Clean Power Plan seems likely to incentivize fuel switching from coal to natural gas. Changes in deployment of nuclear generation may also impact dispatch order. Further, deeper application of intermittent renewables, smart grid, and energy storage seem likely to have impacts on dispatch order and correspondingly drive needs for CCS to be used intermittently and on generators who are supplied with natural gas. Increasing use of natural gas also creates different non-combustion CO2 sources. Many unconventional gas sources have high CO2 impurities, which must be removed prior to market, therefore mitigation of this CO2 is part of the CCS picture. When natural gas is compressed to NLG, additional purification typically includes further lowering CO2. Traditionally use of CO2 for enhanced oil recovery is based on a steady stream from a natural source. CO2 from gas separation is also available in a steady stream, however the addition of gas resources will shift the location of mitigation regionally and internationally, including to offshore settings. If fossil-fuel-powered electricity generation is used to back-stop intermittent renewables, captured CO2 will be supplied only intermittently. An initial simplified study shows no harm to oil production from intermittent CO2 injection during EOR. The most significant impacts from intermittency would be from the need to oversize surface facilities to accept the high end of variable volumes of CO2. Further, the water-alternating- gas operation commonly used for EOR provides some confidence that intermittent CO2 injection would not be technically difficult. The impact of intermittency on capture operations may shift emphasis to lower CAPEX operations, and further study is needed

What to do with CO2: The Knowns and Unknowns of Geologic Sequestration and CO2 EOR in Greenhouse Gas Context

Bureau of Economic Geolog

Monitoring and verification issues for carbon storage

Bureau of Economic Geolog

Case Study: Monitoring an EOR project to document sequestration value

Bureau of Economic Geolog

CO2-EOR as geologic storage: Monitoring for permanence

Bureau of Economic Geolog

Status, Challenges, and Potential Capacity of Reliable Geologic Storage of CO2

CO2 captured from point sources such as power generation and industrial facilities can be compressed, transported and injected into permeable geologic strata below and isolated from freshwater and the surface; this results in storage of the Co2 within the pore space in the subsurface. The transport, injection and storage processes are mature, with an experience of more than 40 years of injection and dozens of intensely characterized, monitored and modeled demonstration sites globally. However some questions remain. For example what are the limitations on the storage capacity, in particular, how much injection is too much, or too fast, and what settings are too unknown or too risky? How much evidence is needed before stakeholder and regulator confidence is sufficiently established to cross project thresholds, such starting the project, continuing a mature project, and closing a completed project? What are the best practices to manage and mitigate should an unacceptable event occur? Storage sites can be developed within depleted hydrocarbon reservoirs or developed in previously unused formations in which pores are filled with brine (called saline formations), and each can be in onshore or offshore settings. CO2 can be used alone or in combination with other fluids to extract hydrocarbons, a process known as CO2 enhanced oil recovery (EOR). EOR generates revenue for the capture and storage process and results in large volume effective storage at low risk. However the whole system carbon balance is impacted by oil production and operations. Each of these storage site types has a distinctive risk profile for the class, as well as a site specific risk of costs, Co2 loss, or other unacceptable events such as induced seismicity

Investigation of water displacement following large CO2 sequestration operations

The scale of CO2 injection into the subsurface required to address CO2 atmospheric concentrations is unprecedented. Multiple injection sites injecting into multiple formations will create a large excess pressure zone extending far beyond the limited volume where CO2 is present. In a closed system, additional mass is accommodated by the compressibility of system components, an increase in fluid pressure, and possibly an uplift of the land surface. In an open system, as assumed in this analysis, another coping mechanism involves fluid flux out of the boundaries of the system, in which case the fresh-water-bearing outcrop areas, corresponding to the up-dip sections of the down-dip formations into which CO2 is injected, could be impacted. A preliminary study using a MODFLOW groundwater model extending far down-dip shows that injecting a large amount of fluid does have an impact some distance away from the injection area but most likely only in localized areas. A major assumption of this preliminary work was that multiphase processes do not matter some distance away from the injection zones. In a second step, presented in this paper, to demonstrate that a simplified model can yield results as useful as those of a more sophisticated multiphase-flow compositional model, we model the same system using CMG-GEM software. Because the chosen software lacks the ability to deal easily with unconfined water flow, we compare fluxes through time, as given by MODFLOW and CMG-GEM models at the confined/unconfined interface.Bureau of Economic Geolog

The state of the art in monitoring and verification— ten years on

In the ten years since publication of the IPCC Special Report on CCS, there has been considerable progress in monitoring and verification (M&V). Numerous injection projects, ranging from small injection pilots to much larger longer-term commercial operations, have been successfully monitored to the satisfaction of regulatory agencies, and technologies have been adapted and implemented to demonstrate containment, conformance, and no environmental impact. In this review we consider M&V chiefly from the perspective of its ability to satisfy stakeholders that these three key requirements are being met. From selected project examples, we show how this was done, and reflect particularly on the nature of the verification process. It is clear that deep-focussed monitoring will deliver the primary requirement to demonstrate conformance and containment and to provide early warning of any deviations from predicted storage behaviour. Progress in seismic imaging, especially offshore, and the remarkable results with InSAR from In Salah are highlights of the past decade. A wide range of shallow monitoring techniques has been tested at many sites, focussing especially on the monitoring of soil gas and groundwater. Quantification of any detected emissions would be required in some jurisdictions to satisfy carbon mitigation targets in the event of leakage to surface: however, given the likely high security of foreseeable storage sites, we suggest that shallow monitoring should focus mainly on assuring against environmental impacts. This reflects the low risk profile of well selected and well operated storage sites and recognizes the over-arching need for monitoring to be directed to specific, measureable risks. In particular, regulatory compliance might usefully involve clearer articulation of leakage scenarios, with this specificity making it possible to demonstrate “no leakage” in a more objective way than is currently the case. We also consider the monitoring issues for CO2-EOR, and argue that there are few technical problems in providing assurance that EOR sites are successfully sequestering CO2; the issues lie largely in linking existing oil and gas regulations to new greenhouse gas policy. We foresee that, overall, monitoring technologies will continue to benefit from synergies with oil and gas operations, but that the distinctive regulatory and certification environments for CCS may pose new questions. Overall, while there is clearly scope for technical improvements, more clearly posed requirements, and better communication of monitoring results, we reiterate that this has been a decade of significant achievement that leaves monitoring and verification well placed to serve the wider CCS enterprise