Predicted water chemistry trends in North Sea formation brines

Osborne, Carly; Ravenscroft, Peter; McCracken, I. R.

doi:10.1016/0264-8172(94)90005-1

Cited by 4 publications

(1 citation statement)

References 4 publications

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“…Secondary phases start precipitating from a pore fluid when the latter becomes saturated with these phases and a dynamic, tightly temperature dependent equilibrium between fluid and phase evolves. This principle of mineralfluid interaction reaching equilibrium, which is the basis of geothermometry (Giggenbach, 1981(Giggenbach, , 1988), has been extensively studied in sedimentary settings (Bjørlykke and Gran, 1994;Connolly et al, 1990;Furlan et al, 1995;Garrels and MacKenzie, 1972;Hanor, 1994;Hutcheon et al, 1993;Michael and Bachu, 2002;Osborne et al, 1994;Stueber and Walter, 1991;Yardley et al, 2003) and successfully applied to reconstruct in-situ compositions of sedimentary formation waters (Bazin et al, 1997;Palandri and Reed, 2001). Especially the latter of these last two references provides a detailed protocol that can be applied to the scarce chemical information of the petroleum well dataset to stitch together a consistent picture of the likely chemical composition of the geothermal waters permeating the Perth Basin.…”

Section: Formation Water Reconstructionmentioning

confidence: 99%

Geochemical modelling of petroleum well data from the Perth Basin. Implications for potential scaling during low enthalpy geothermal exploration from a hot sedimentary aquifer

Wolff-Boenisch

Evans

2013

Applied Geochemistry

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Chemical analyses derived from petroleum exploration wells are notorious for their lack of key solute data and their potential to represent mixtures of reservoir and drilling fluids rather than pristine formation compositions. These drawbacks notwithstanding, they usually pose the only access to the reservoir geochemistry. Two literature protocols were applied to a dataset of incomplete major element analyses from 148 petroleum well samples from a database compilation of the Perth Basin whose deeper aquifers may serve as potential hot sedimentary aquifers for geothermal direct heat applications. The first protocol included a set of quality control criteria that reduced the number of relatively genuine formation well samples from the raw data pool by 71%. The remaining well analyses are invariably NaCl solutions of low to medium alkalinity and an ionic strength only occasionally reaching seawater salinity. The low amount of total dissolved solids indicates the absence of extended evaporites in the North Perth Basin and the prevalence of meteoric water infiltration and circulation at depths. The culled well samples underwent as a second protocol a forced equilibrium treatment to reconstruct in-situ reservoir concentrations of missing elements (Si, Al, K), organic acid anions and non-carbonate alkalinity, and pH. The petroleum well samples were modelled to be in equilibrium with chalcedony (and kaolinite, albite, and paragonite) in the reservoir which yielded better convergence than using quartz instead. The derived formation temperatures correspond to geothermal gradients in the majority of cases between 25-35°C, in accord with literature findings. Those wells drilled to depth <1600 m returned questionably high geothermal gradients, an indication of incomplete mineral-fluid equilibrium. The measured pH (at ambient temperature) deviated in >90% of the wells from the calculated pH, either due to degassed CO 2 or unaccounted acetate alkalinity. The wells were further modelled to be undersaturated with respect to amorphous silica and anhydrite and not likely to experience scaling of any of these two phases during geothermal 2 production at depth <3800 m. For calcite, scaling predictions depend in how far bubbling and phase segregation can be suppressed. For the six different stratigraphies investigated here, calculated bubble points were low, indicating that pressurisation of the entire production and reinjection line seems viable. Based on a calcite growth model from the literature it is shown that, if bubble formation and concomitant carbonate flash scaling cannot be averted, the production well should be as shallow as the temperature requirements of the geothermal production allow for. This study promotes the application of readily accessible protocols and a scaling model to deep well samples that may otherwise appear to have little geochemical value because of the way the samples were collected and handled. After data culling and treatment, insights into the geochemistry and scaling potential of deep clastic format...

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Section: Formation Water Reconstructionmentioning

confidence: 99%

Geochemical modelling of petroleum well data from the Perth Basin. Implications for potential scaling during low enthalpy geothermal exploration from a hot sedimentary aquifer

Wolff-Boenisch

Evans

2013

Applied Geochemistry

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Coupled Analysis of Damage Formation Around Wellbores

Guimarães

Gens

Olivella

2004

Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems - Fundamentals, Modelling, Experiments and Applications

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Part 4: Compositional variations of North Sea formation waters

Warren

Smalley

Howarth

1994

Memoirs

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A total of 236 individual water analyses from over 70 fields in the North Sea and Norwegian Haltenbanken area were provided by field operators or collated from the literature (Table 4.1). All the data from the field operators were supplied as representative analyses of the formation water for that field. Most of the analyses supplied were routine ten ion analyses with accompanying data on sample type, water resistivity and reservoir conditions. Where these accompanying data were not supplied but were available from other sources, they have been added to the original contribution. Previously published formation water analyses have also been included with accompanying data where available.Minor ions, such as bromide and lithium, trace metals, organic species such as acetate, and isotopic data were seldom reported. Consequently, maps and figures have only been constructed of the major cations, anions, total dissolved solids and Rw.All users of the water data compiled here should be aware of possible variations in data quality. There are a number of concerns, most notably the chemical analysis method, sampling artifacts and sample contamination.The majority of the chemical analyses of formation waters compiled were not performed by the North Sea field operators themselves, but were produced under contract by a number of service companies. Although routine laboratory methods were used to obtain the data reported here, different methods have been used between laboratories and over time due to improved instrumentation and analytical methods over the last 25 years of oil and gas production from the

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Predicted water chemistry trends in North Sea formation brines

Cited by 4 publications

References 4 publications

Geochemical modelling of petroleum well data from the Perth Basin. Implications for potential scaling during low enthalpy geothermal exploration from a hot sedimentary aquifer

Geochemical modelling of petroleum well data from the Perth Basin. Implications for potential scaling during low enthalpy geothermal exploration from a hot sedimentary aquifer

Coupled Analysis of Damage Formation Around Wellbores

Part 4: Compositional variations of North Sea formation waters

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