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

•We review in detail five sampling techniques to acquire fluids from deep aquifers.•We examine and discuss benefits and drawbacks of these sampling methodologies.•We present two sample recovery techniques for one and two phase fluids.•We present a tabulated summary to guide acquisition of deep fluid samplers.

SummarySampling fluids from deep wells and subsequent sample treatment prior to gas and liquid analysis requires special equipment and sampling techniques to account for the relatively high temperatures, pressures, and potential gas content present at depth. This paper reviews five major sampling methodologies, ranging from different in situ wireline samplers to producing pumps and the U-tube and discusses their advantages and drawbacks in the light of three principal applications, deep groundwater research, unconventional geothermal exploration, and carbon storage. Geochemical modelling is used to investigate the probability of decarbonation and concomitant carbonate scaling during sampling in geothermal and carbon sequestration applications. The two principal sample recovery techniques associated with the fluid samplers are also presented.