Burial diagenesis and thermochemical sulfate reduction, Smackover Formation, southeastern Mississippi salt basin

Deep Fluids in Sedimentary Basins

“…This line passes very close to the point giving the d-values for the water in the Norphlet Formation, which is that expected from evaporating seawater at the point of halite precipitation. The d-values of the samples from the Smackover Formation were initially close to those from the Norphlet Formation; the 1-2% shifts in d 18 O values are probably related to isotopic exchange with the enclosing carbonate minerals (Heydari and Moore, 1989).…”

The separate production of H2S from the thermal reaction of hydrocarbons with magnesium sulfate and sulfur: Implications for thermal sulfate reduction

“…Sedimentary gypsum and anhydrite are thermodynamically unstable in the presence of hydrocarbons (Worden and Smalley, 1996). The hydrophile nature of solid anhydrite could increase the likelihood of TSR (Heydari and Moore, 1989). The presence of MgSO 4 can significantly reduce the temperatures at which TSR occurs (Gillaizeau and Tang, 2001;Zhang et al, 2007Zhang et al, , 2008aLu et al, 2011), the high reactivity of this sulfate being attributed to HSO À 4 formation under acidic conditions reducing the activation energy between MgSO 4 and hydrocarbon reactants (Zhang et al, 2008b) and so destabilisation the SO 4 by the formation of contact ion-pairs (Ma et al, 2008 The most common TSR product is H 2 S, which has high solubility.…”

Generation of isotopically and compositionally distinct water during thermochemical sulfate reduction (TSR) in carbonate reservoirs: Triassic Feixianguan Formation, Sichuan Basin, China

“…Thermochemical sulfate reduction (TSR) occurs when petroleum reacts with dissolved sulfate, derived from the dissolution of sulfate minerals (mainly anhydrite but also celestite and barite) at elevated temperatures (greater than approximately 100 to 140ºC for oil and greater than 140ºC for gas) (Cai et al, 2004;Heydari and Moore, 1989;Worden and Smalley, 2004;Worden et al, 1995). A general reaction Page 3 can simply be written as follows:…”

“…sulfate + petroleum  calcite + H 2 S ± H 2 O ± CO 2 ± S ± altered petroleum (R1) TSR leads to significant alteration of petroleum and generates a variety of reduced forms of sulfur (S and H 2 S) and oxidized forms of carbon (carbonate minerals and CO 2 ) as well as a combination of water, sulfides, organosulfur compounds and bitumen (Bildstein et al, 2001;Cai et al, 2010;Cai et al, 2003;Cai et al, 2004;Heydari, 1997;Heydari and Moore, 1989;Krouse et al, 1988;Machel, 1987;Machel et al, 1995;Worden et al, 2000;Worden et al, 1995.…”