In 1966 petroleum production in western Europe decreased 3% compared with 1965, with all countries except Yugoslavia and Spain having declining output. Natural gas production increased greatly, chiefly as a result of expansion of pipelines in The Netherlands and Germany, though much greater production from those countries is expected after completion of facilities under construction. In the southern part of the United Kingdom sector of the North Sea, a 1966 discovery, the Leman field, 30 mi offshore, was estimated to have reserves of 6 Tcf of gas in the Lower Permian sandstone. Another field, Hewett, found gas in 2 sandstone members of the Lower Triassic, and an oil discovery was made in a Permian dolomite on another structure. At least 2 other Lower Permian new-field gas discoveries were made. The West Sole gas field, discovered in 1965, was connected to shore by a pipeline. The first wells were completed in the Danish and Norwegian sectors of the North Sea, and drilling continued at a reduced rate in the German sector. No progress was made in enactment of North Sea oil and gas regulations by The Netherlands, and the boundaries between Germany and its neighbors, Denmark and The Netherlands, remained unsettled except for short segments near shore. In Austria a new deep oil discovery was made in Mesozoic limestone in the Vienna basin and other oil and gas discoveries were made in Miocene sandstones in that basin. Three deep wells were drilled through frontal Alpine nappes to total depths in crystalline basement. In France exploration activity declined exce t along the frontal zone of the Pyrenees, where several deep wells were drilled in search of gas. In this area the Meillon gas field was extended 6 mi west and there was also an oil discovery. A new depth record for Europe, 20,686 ft, was made by Meillon No. 2. The first wells were drilled off the French coast and one of these had significant but noncommercial oil shows. In Germany 2 gas discoveries were made. Gas high in nitrogen was found in Lower Permian sandstone in Wustrow, near the East German border. Schnaitsee field in southern Bavaria, was productive in the Oligocene. Important new-pool and extension wells were completed in northwest German gas fields. In Italy significant outpost and new-pool extension wells were completed in the continuation of the Po basin into the Adriatic S a. Several apparently minor gas discoveries were made in peninsular Italy. There was a great decrease in exploration in The Netherlands while new legislation was awaited. A gas discovery was made in Friesland. In Spain there were 2 minor oil discoveries and another exploratory well tested gas. In the United Kingdom an important gas discovery and a smaller one were made in Yorkshire. A gas field south of London found in 1965, was further developed. An oil discovery was made in the Drava Valley of Yugoslavia, and exploration interest in the Adriatic zone increased. A deep test in Spitsbergen was abandoned. In the Soviet Union, oil production increased to more than 5 million b/d and gas production to 14 Bcf/d. Plans were made to connect large gas fields found in recent years in northwestern Siberia to consuming areas in European Russia and possibly to Italy, by a large-diameter pipeline. The first offshore self-elevating drilling platform was placed in operation in the Caspian Sea. An important gas discovery, Achak, was made in Turkmenistan and there were significant oil discoveries in Crimea and in various parts of the Ural-Volga region.