ABSTRACT:

OMV (ALBANIEN) onshore Exploration GmbH operates three exploration blocks in Albania in co-operation with Hellenic Petroleum S.A. In 2003/4 OMV drilled two exploration wells in Blocks 4 and 5 onshore, namely Palokastra-1 and Kanina-1. Kanina-1 was located near Vlora at an elevation of 616m above sealevel on Tragjasi Mountain, a fractured and karstified carbonate outcrop. Losses were expected as observed in other wells drilling surface carbonates. Shifting of location was not feasible for geological and technical reasons. Preparations were made in accordance with expectations, including construction of a lined 5,000m3 water pit sourced from Vlora water enterprise station, having a cementing unit with bulk silos standby on site, and mixing a thixotropic mixed metal hydroxide mudsystem. Total losses occurred in 26" and 18–1/2" hole sections and the decision was made to not to drill blind, but to cure the losses for the following reasons: - vibrations on the drillstring - excessive wear on the stabilizers - environmental considerations to avoid any groundwater pollution The measures to cure losses included conventional techniques such as LCM pills or cement plugs, but due to the unsatisfactory results of these techniques, additional unconventional methods were applied. Efforts to cure losses reached an economic limit and so it was decided to drill blind until section TD. This needed environmentally sensitive mud systems, provision of sufficient amounts of water for hole cleaning, bit cooling and vibration dampening, regular blacklight inspections of the drillstring components and nonstandard geological monitoring based on drilling parameters, cuttings taken from the bit or BHA components, and junk sub runs for samples. Another challenge was to conduct the cement jobs for the 20" and 16" casings. Cementing after drilling without returns needed special planning to get sufficient cement behind the casings to support the BOP loadings and the integrity of the shoe. The two sections were successfully drilled, casing run and cemented down to 1,613 m MD

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