Review of available fluid sampling tools and sample recovery techniques for groundwater and unconventional geothermal research as well as carbon storage in deep sedimentary aquifers

The syringe sampler: An inexpensive alternative borehole sampling technique for CO2-rich fluids during mineral carbon storage

“…These pressurized downhole samples are routinely degassed, either at the wellhead during production or after transporting the sample to the surface and the in situ pH, alkalinity, and mineral saturation indices are consistently recalculated with geochemical modeling software . This is a legitimate approach as long as carbonate precipitation during CO 2 degassing can be compellingly ruled out; the pH/pCO 2 conditions under which carbonate formation is likely during sampling into a vacuum sampler have been discussed in detail elsewhere . Those carbon storage projects, such as CarbFix, targeting (ultra)mafic terrains and/or the use of a carbonated solution as injection fluid are more prone to potential carbonate precipitation upon degassing and rely more than any other carbon storage initiative on accurate data of the aqueous geochemistry and its temporal evolution in the reservoir.…”

“…Another important goal was to design an affordable, cost‐conscious alternative to already available well‐based subsurface monitoring tools and commercial wireline samplers. Based on the recent review on available downhole sampling techniques for groundwater in different deep settings, our syringe sampler is a very economic sampling solution. Besides extensive lab and field tests, the PDS was successfully deployed during a small scale CO 2 injection test in spring of 2012.…”

“…In this study, the terms ‘syringe sampler’ and ‘PDS’ (for ‘positive displacement sampler’) are used interchangeably to describe this type of wireline deep well sampler. A recent review article describes and explains in detail the fundamental differences of available downhole sampling techniques, which is beyond the scope of this paper. Suffice it here to say that our sampler works similar to a combination of a positive displacement sampler and a syringe.…”

“…Any pressure loss and concomitant gas bubble formation during sampling and subsequently on the surface has to be suppressed which requires maintaining the in situ reservoir pressure of the sample prior to analysis. It is not desirable to evacuate the sampler prior to sampling as this would lead to vigorous phase segregation, which could cause carbonate precipitation and clogging of the valve orifices . Hence, commercial vacuum samplers cannot be deployed.…”

Integrated Research as Key to the Development of a Sustainable Geothermal Energy Technology

“…Several wireline probes for sampling borehole water from different companies exist. [139] Very simple devices samplet he fluid by opening an inlet valve of an evacuated sample chamber. Flow-through samplers trap as ampleb yc losing inlet and outletv alves.T hese probes avoid temperature shockb ecause the devices are permanently heated to the reservoir temperature.T he disadvantage of this sampling strategy is that it may lead to contamination on surfaces and in dead volumes.…”