The use of tracers to assess drill-mud penetration depth into sandstone cores during deep drilling: method development and application

Influence of drill mud on the microbial communities of sandstone rocks and well fluids at the Ketzin pilot site for CO2 storage

“…Pristine StF rock cores were collected in 2012, during the coring of the deep (~700 m) well CO2 Ktzi 203/2012 (short name: Ktzi 203) across the storage formation (Martens et al 2014). Pristine Exter Formation (here named ExF) rocks (first aquifer above the StF caprock) were acquired in 2011, during the drilling of the shallow (~450 m) hydraulic and geochemical monitoring well Hy Ktzi P300/2011 (short name: Ktzi P300) (Pellizzari et al 2013). …”

“…Only uncontaminated rock core samples were used in the laboratory experiments. The drill mud contamination control using fluorescein and the preparation of pristine inner core plugs are explained in detail in Pellizzari et al (2013). The microbial baseline characterization of the ExF rock cores (ExF 4-BL, ExF 6-BL and ExF 9-BL) is included in Pellizzari et al (2016) and is compared to the results of this work in the discussion part.…”

Comparison of the microbial community composition of pristine rock cores and technical influenced well fluids from the Ketzin pilot site for CO2 storage

“…During the pump test in the SOW, six samples were collected after 3, 5, 7, 10, 11 and 14 m 3 of fluid production to characterize the microbial community composition. The drill fluid contamination control is described in Pellizzari et al (2013). , 9600 x-g for 1 h at 4 °C) and fixed with PFA (4 % final concentration).…”

“…For highly sensitive molecular biological analyses, it is important to assess the drill mud content in well fluid and rock samples Pellizzari et al 2013) because microorganisms might be introduced with the mud. Moreover, organic polymers can serve as nutrients for microorganisms, as occurred in the injection well, where these polymers stimulated microbial activity, affecting the injectivity Morozova et al 2010).…”

“…A microbiological sampling of pristine rock cores and water samples from these wells requires specific techniques to avoid contamination (Pedersen et al 1997;Basso et al 2005;Kallmeyer et al 2006). A fluorescent dye tracer, sodium fluorescein, was added to the drill mud to estimate the drill mud penetration depth into the rock cores and determine the amount of this mud in the collected fluid samples Pellizzari et al 2013). …”