Lithological and Petrophysical Core-Log Interpretation in CO2SINK, the European CO2 Onshore Research Storage and Verification Project

Abstract

The storage of carbon dioxide (CO2) in saline aquifers is one of the most promising options for Europe to reduce emissions of greenhouse gases from power plants to the atmosphere and to mitigate global climate change. The CO2SINK project is a R&D project, mainly supported by the European commission, the German Federal Ministry of Education and Research, and the German Federal Ministry of Economics and Technology, targeted at developing an in situ laboratory for CO2 storage. Its aims are to advance the understanding of the processes involved in underground CO2 storage, evaluate applicable monitoring techniques, and provide operational experience, which all contribute to the development of harmonized regulatory frameworks and standards for CO2 geological storage. The preparatory phase of the project involved a baseline geological site exploration and the drilling in 2007 of one injection and two observation wells, as well as the acquisition of a geophysical baseline and geochemical monitoring, in Ketzin located near to Berlin, Germany. The target saline aquifer is the Triassic Stuttgart Formation situated at about 630-710 m (2070-2330 ft), that is made of siltstones and sandstones interbedded by mudstones. A comprehensive borehole logging program was performed consisting of routine well logging to which an enhanced logging program was added for one well that record nuclear magnetic resonance and borehole resistivity images predominantly to better characterize the storage formation. A core analysis program carried out on reservoir rock and caprock included measurements of helium porosity, nitrogen permeability and brine permeability. Carbon dioxide injection started in 2008 and will last for about 2 years. The paper focuses on the integrated approach of combining lithological and petrophysical data from both laboratory and well logging analysis predominantly for the reservoir/storage section of the Ketzin site. This method was successfully applied in two wells with extensive core data. In the third well, where few core data exist, the section was characterized successfully by analogy. Introduction Since the publication of the Intergovernmental Panel on Climate Change Report (IPCC, 2005), geological storage of carbon dioxide (CO2) was recognized in the public as an important concept for reducing greenhouse gas emissions into the atmosphere. Notwithstanding technology, the understanding of the storage geometry, from the near surface to below the storage reservoir is mandatory. Another prerequisite for a successful operating storage project is the detailed knowledge of rock and fluid properties that do depend on pressure and temperature conditions. These data serve as an input for reservoir models and decisions on the injection regime as well as decisions on the monitoring of long-term CO2 migration after injection.

Zero-Offset VSP Monitoring of CO2Storage: Impedance Inversion and Wedge Modelling at the Ketzin Pilot Site

“…For the second sample, the maximum measurable CO 2 saturation was 40%, associated with a Pwave velocity reduction of 20%-21%. These results reflect the heterogeneity of the reservoir sandstone [21]. [19]).…”

Quantitative evaluation of thin-layer thickness and CO2mass utilizing seismic complex decomposition at the Ketzin CO2storage site, Germany

“…6). The baseline model was established according to the velocity and density data measured in the Ktzi 201 well (Norden et al 2010). The yellow inverted trapezoid, which is the second layer, (Fig.…”

“…Muddy, flood-plain-facies (poor reservoir quality) alternates with sandy channel-facies (good reservoir quality) in the heterogeneous Stuttgart Formation. The immediate caprock of the reservoir formation is formed by the 210-m-thick Weser and Arnstadt formations consisting of mudstones and anhydritic mudstones (Norden et al 2010). A 10-20-m-thick anhydrite layer with low porosity and permeability is present at the top of the Weser formation.…”

Borehole seismic monitoring of CO2 storage within a saline aquifer at Ketzin, Germany

“…• Various borehole logging techniques (sonic, density, cement bond, pulsed neutron gamma...) and the interpretation of cores (Prevedel et al (2008(Prevedel et al ( , 2009Norden et al (2010); Ivanova et al (2012)). …”