Exploration of drilling techniques for ultra-high pressure fluid traps in salt gypsum layers encountered during drilling in the BU block of the Missan oilfield in Iraq
The Missan Oilfield in Iraq contains high-pressure brine layers in the composite saline layer section,in which the 12-1/4"section of a well in the BU block was drilled through ultra-high-pressure fluid traps,which made the operation of this section of the well without a safe drilling fluid density window,and the downhole complexities,such as gas intrusion,brine overflows,leakage,and tight hole,were frequently occurred during the operation.During subsequent drilling,strict ECD control technology was adopted to simplify the combination of drilling tools and optimize the parameters;during non-drilling time,the borehole was stabilized by layered slurry columns,and the speed of RIH/POOH was controlled in sections,which avoided the downhole complications caused by local ultra-high-pressure fluid formations such as surging,leaking and stuck,and ensured the safety of the borehole operation,and accumulated the operation experience of the same well condition in the oilfield,and also provided the operation ideas for the same kind of formations in other oilfields.
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