Complex sentence: In 1998, Talisman made one of its most controversial moves when it purchased Arakis Energy, which was involved in the Sudanese oil industry through a 25% interest an oil project operated by the Greater Nile Petroleum Operating Company (GNPOC).
Split into simpler sentences: In 1998, Talisman made one of its most controversial moves when it purchased Arakis Energy. The acquired business had involvement in the Sudanese oil industry through a 25% interest in an oil project operated by the Greater Nile Petroleum Operating Company (GNPOC).