Abstract
In an effort to evaluate mineral-water isotopic exchange during cyclic steam stimulation (CSS), solutions and <2 μm berthierine-dominated="" solids="" from="" the="" clearwater="" formation="" oil="" sands="" of="" alberta,="" canada="" were="" analyzed="" for="" stable="" isotope="" compositions="" before="" and="" after="" reaction="" in="" autoclaves="" for="" 1008 h="" at="" 250 °c.="" there="" was="" no="" significant="" change="" in="" solution="" δ18o="" and="" δ2h,="" which="" is="" consistent="" with="" the="" high="" water/mineral="" ratio="" used="" in="" the="" experiments.="" the="" solids="" showed="" a="" marked="" decrease="" in="" both="" δ18o="" and="" δ2h="" following="" the="" experiments.="" pre-run="" solids="" have="" δ18o="" of="" +9.5="" to="" +12.9‰="" and="" δ2h="" of="" −114="" to="" −113‰,="" whereas="" post-run="" solids="" have="" δ18o="" of="" −4.7="" to="" +2.1‰="" and="" δ2h="" of="" −147="" to="" −128‰.="" neither="" oxygen-="" nor="" hydrogen-isotope="" equilibrium="" was="" established="" between="" the="" solids="" and="" the="" solutions.="" calculation="" suggests="" that="" oxygen-isotope="" exchange="" (44–58%)="" was="" greater="" between="" the="" solids="" and="" the="" solutions="" than="" was="" the="" case="" for="" hydrogen="" isotopes="" (23–50%).="" we="" propose="" that="" this="" behaviour="" resulted="" from="" partial="" inheritance="" of="" the="" pre-run="" berthierine="" structure="" during="" formation="" of="" the="" post-run="" smectite,="" chlorite-smectite="" and="" chlorite.="" this="" process="" confounds="" the="" use="" of="" clay="" mineral="" stable="" isotope="" compositions="" as="" a="" temperature="" indicator="" of="" in="" situ="" steam/steam="" condensate="" interaction="" with="" oil-sands="" reservoirs.="" the="" results="" also="" suggest="" an="" additional="" mechanism="" by="" which="" new="" clay="" minerals="" can="" be="" formed="" during="" css-related,="" artificial="">