H2S-generation by Methane-dominated TSR and Carbon Isotope Fractionation in Lower Triassic Feixianguan Formation, Northeast Sichuan Basin

详细信息   

• 责任者：Cai ChunFang(Key Lab of Petroleum Resources ; Institute of Geology and Geophysics ; Chinese Academy of Sciences ; Beijing 100029 ; China) ; Cai LiuLu
• 刊名：Acta Petrologica Sinica
• 出版年：2012
• 卷期：28(3)
• 页码：p.889-894
• issnNo：ISSN1000-0569
• isbnNo：CN11-1922/P

摘要

Methane-dominated TSR has been proposed to occur in Lower Triassic Feixianguan Formation oolitic dolomite reservoirs on the northeast side to the Kaijiang-Liangping basin (Cai WEIGHT: normal; FONT-SIZE: 12px; WORD-SPACING: 0px; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; LINE-HEIGHT: 15px; FONT-FAMILY: ����,verdana; WHITE-SPACE: normal; LETTER-SPACING: normal; BACKGROUND-COLOR: rgb(255,255,255); FONT-VARIANT: normal; orphans: 2; widows: 2; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px">et al., 2004), but not in oolitic limestone on the southwest side where there is no significant H₂S and low porosity. TSR-calcite is shown to have δ¹³C

    

values mainly from -10‰ to -19‰ and coexists with solid bitumen, elemental sulfur, pyrite and quartz, and has replaced dolomite, anhydrite and celestite. However, present CO₂ gas has δ¹³C values mainly from -2‰

    

to +2‰, suggestive of dissolution of carbonates (likely dolomite) after TSR-calcite precipitation. Natural gases from Changxing Fm., Feixianguan Fm. and Jialingjiang Fm. from the East to Puguang gasfield show a logarithmic relationship between methane δ¹³C₁ and residual hydrocarbons (HCs). Based on this relationship, it can be

    

calculated that about 15% methane of well Du4 gas from the Feixianguan Fm. may have been oxidized as the result of TSR.