Abstract
A well in Burgan field is producing oil with high H2S content from Burgan reservoir, which was never observed in this part of the field. The H2S appears to be leaking from different reservoir layers. Two possible sources of the H2S in this field are the shallow Umm Er Radhuma and Tayarat formations, above the Burgan reservoir, and the deep Ratawi and Minagish formations below the reservoir.
The Burgan formation for this well was cased with two casings (9.625 in. and 13.375 in.). The 9.625-in. casing was cemented, and cement evaluation logs were run. However, no cement evaluation logs were recorded after the 13.375-in. casing was cemented. In the past, it was not possible to evaluate cement for a second barrier. However, with the new development in the advanced sonic and ultrasonic measurement, it became possible to evaluate cement for the first barrier (9.625 in.) and the second barrier (13.375 in.) simultaneously, which was utilized for this well for cement evaluation and advanced fracture analyses. In addition to the cement evaluation, a combination of noise, corrosion, and production logs was used to further enhance the investigations. The noise and the production log investigations were performed through Y-tool with an electric submersible pump that was used to further increase the drawdown to activate and excite any source of leak during the investigation.
