The Global Energy Assessment (GEA) brings together over 300 international researchers to provide an independent, scientifically based, integrated and policy-relevant analysis of current and emerging energy issues and options. It has been peer-reviewed anonymously by an additional 200 international experts. The GEA assesses the major global challenges for sustainable development and their linkages to energy; the technologies and resources available for providing energy services; future energy systems that address the major challenges; and the policies and other measures that are needed to realize transformational change toward sustainable energy futures. The GEA goes beyond existing studies on energy issues by presenting a comprehensive and integrated analysis of energy chalenges, opportunities and strategies, for developing, industrialized and emerging economies. This volume is a invaluable resource for energy specialists and technologists in all sectors (academia, industry and government) as well as policymakers, development economists and practitioners in international organizations and national governments.

Global Energy Assessment: Toward a Sustainable Future

Geological storage of CO2 in saline aquifers—A review of the experience from existing storage operations

This paper provides a review of the geomechanics and modeling of geomechanics associated with geologic carbon storage (GCS), focusing on storage in deep sedimentary formations, in particular saline aquifers. The paper first introduces the concept of storage in deep sedimentary formations, the geomechanical processes and issues related with such an operation, and the relevant geomechanical modeling tools. This is followed by a more detailed review of geomechanical aspects, including reservoir stress-strain and microseismicity, well integrity, caprock sealing performance, and the potential for fault reactivation and notable (felt) seismic events. Geomechanical observations at current GCS field deployments, mainly at the In Salah CO2 storage project in Algeria, are also integrated into the review. The In Salah project, with its injection into a relatively thin, low-permeability sandstone is an excellent analogue to the saline aquifers that might be used for large scale GCS in parts of Northwest Europe, the U.S. Midwest, and China. Some of the lessons learned at In Salah related to geomechanics are discussed, including how monitoring of geomechanical responses is used for detecting subsurface geomechanical changes and tracking fluid movements, and how such monitoring and geomechanical analyses have led to preventative changes in the injection parameters. Recently, the importance of geomechanics has become more widely recognized among GCS stakeholders, especially with respect to the potential for triggering notable (felt) seismic events and how such events could impact the long-term integrity of a CO2 repository (as well as how it could impact the public perception of GCS). As described in the paper, to date, no notable seismic event has been reported from any of the current CO2 storage projects, although some unfelt microseismic activities have been detected by geophones. However, potential future commercial GCS operations from large power plants will require injection at a much larger scale. For such large-scale injections, a staged, learn-as-you-go approach is recommended, involving a gradual increase of injection rates combined with continuous monitoring of geomechanical changes, as well as siting beneath a multiple layered overburden for multiple flow barrier protection, should an unexpected deep fault reactivation occur.

/pdf/the-geomechanics-of-co2-storage-in-deep-sedimentary-3k6vmdsuf7.pdf

The geomechanics of CO2 storage in deep sedimentary formations

We present an interpretational framework for the analysis of a diverse set of geological structures that breach sealing sequences and allow fluids to flow vertically or subvertically across the seal. In so doing, they act as seal bypass systems (SBS). We define SBS as seismically resolvable geological features embedded within sealing sequences that promote cross-stratal fluid migration and allow fluids to bypass the pore network. If such bypass systems exist within a given seal sequence, then predictions of sealing capacity based exclusively on the flow properties (capillary entry pressure and hydraulic conductivity) of the bulk rock can potentially be negated by the capacity of the bypass system to breach the grain and pore network. We present a range of examples of SBS affecting contrasting types of sealing sequences using three-dimensional (3-D) seismic data. These examples show direct evidence of highly focused vertical or subvertical fluid flow from subsurface reservoirs up through the seal sequence, with leakage internally at higher levels or to the surface as seeps.We classify SBS into three main groups based on seismic interpretational criteria: (1) fault related, (2) intrusion related, and (3) pipe related. We show how each group exhibits different modes of behavior with different scaling relationships between flux and dimensions and different short- and long-term impacts on seal behavior.

Seal bypass systems

The Messinian Salinity Crisis: Past and future of a great challenge for marine sciences

Lessons learned from 14 years of CCS operations: Sleipner, In Salah and Snøhvit

Constraints on the in situ density of CO2 within the Utsira formation from time-lapse seafloor gravity measurements

Virgin rock temperatures are important to hydrocarbon exploration, as these temperatures are necessary for the computation of source rock temperatures, and for hydrocarbon generation computations. Several methods have been developed for determination of virgin rock temperatures from maximum temperatures recorded during logging in the past decades. This paper describes an investigation where the calculated virgin rock temperatures from several different methods were examined for bias and accuracy using 18 different measurement series at the Oseberg field. The temperatures were corrected for different depths of burial, and then compared with each other and with drill stem test (DST) measurements to investigate the inaccuracy of the methods. The most advanced methods gave values close to the DST temperatures on average, but with standard deviations as high as 9 degrees C. The less advanced models (like the Horner plot method) have systematically too low virgin rock temperatures (by about 8 degrees C) for the Oseberg field, with standard deviations of 8 degrees C.The errors in calculated virgin rock temperatures are large enough to completely alter predictions of hydrocarbon generation in an area. The large errors are attributed to poor quality data and to physical effects that are not properly taken into account in the temperature calculations. Improved sampling of temperature data can probably reduce the errors to some extent.

Estimates of virgin rock temperature derived from BHT measurements: Bias and error

Storage of CO2 in saline aquifers–Lessons learned from 10 years of injection into the Utsira Formation in the Sleipner area

https://www.sintef.no/globalassets/project/matmora/papers/paper-ghgt.pdf

Christian Hermanrud

Papers

Lessons learned from 14 years of CCS operations: Sleipner, In Salah and Snøhvit

Constraints on the in situ density of CO2 within the Utsira formation from time-lapse seafloor gravity measurements

Estimates of virgin rock temperature derived from BHT measurements: Bias and error

Storage of CO2 in saline aquifers–Lessons learned from 10 years of injection into the Utsira Formation in the Sleipner area

Field-case simulation of CO2 -plume migration using vertical-equilibrium models