Contrasting responses of sulphur isotopes on reservoir souring.

OSTERA, H. A.; PANARELLO, H.0.; CORDERO OTERO, R R; GALLIANO, G.; POLI, M.

Calafate

Congreso; XV Congreso Geológico Argentino; 2002

Petroleum Societe of Canada

<!-- /* Font Definitions */ @font-face {font-family:ArialMT; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-format:other; mso-font-pitch:auto; mso-font-signature:3 0 0 0 1 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0mm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 30.0mm 70.85pt 30.0mm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> ABSTRACT The main cause of reservoir souring in the oil fields is Bacterial Sulfate Reduction. The supporting evidences are the evolution of the exploitation, the dispersed sulfur isotope values of produced H2S for the first reservoir, the isotopic values of water, injection water, production water, and oxygen scavengers (bisulphite) and the relative volumes from different sources of sulphur, sulphate source feeding the process.    Also the distribution pattern, presence of fatty acids in formation waters.  The contrasting response of reservoir two is attributed to a BSR controlled by the rate of sulphate dissolution. However, we cannot discard in this case a pre-existent TSR due to the concentration of ethane-propane and their correlation with 13C values of CO2.