| Abstract |
Well Bar10 in the Bariis sector of the Tiwi field was drilled in 1996 and it produced highly corrosive acid sulfate fluids at a pH of ~3.7. The results of Bar10 and other previously drilled acid-sulfate producers in the same sector (Bar02, Bar03 and Bar09) were discouraging that further drilling in the area, despite its high reservoir temperatures and permeabilities, was shelved. In 1996 a previously non-corrosive well, Bar08, started producing acid sulfate fluids. Fieldwide studies of the chemistry and occurrence of the acid sulfate fluids indicated that they form near the top of the reservoir, due to the interaction of H2S-bearing reservoir steam with downflowing air-saturated meteoric water. Therefore, well Bar08 was redrilled in 2005 and cemented liner installed below the original casing shoe, with the objective of excluding the acid sulfate fluids from the wellbore. The well has been an excellent producer of benign fluids since then. A new well Bar11, was drilled in 2008 with a similar design and is also currently producing a similar high-temperature, benign fluid. |