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Production is compartmentalized due to numerous intraformational seals.

Stratigraphic trapping and faulting are important locally. Carbonate and sandstone reservoirs produce oil and gas primarily from anticlinal traps of Plio-Pleistocene age. Reserves of 4.3 billion barrels of oil equivalent have been discovered in reservoirs that range from pre-Tertiary basement through upper Miocene sandstones and carbonates deposited as synrift strata and as marine shoreline, deltaic-fluvial, and deep-water strata. Eocene through lower Oligocene lacustrine shales and Oligocene through lower Miocene lacustrine and deltaic coaly shales are the mature source rocks. The province consists of Tertiary half-graben basins infilled with carbonate and clastic sedimentary rocks unconformably overlying pre-Tertiary metamorphic and igneous rocks. In November, a magnitude 5.6 quake killed at least 340 people and damaged more than 62,600 homes in parts of West Java.Oil and gas are produced from the onshore South Sumatra Basin Province. Indonesia, a vast archipelago of 270 million people, is frequently struck by earthquakes, volcanic eruptions and tsunamis. Aftershocks measured as strong as 5.8.Īfter an initial tsunami alert, Indonesia’s Meteorology, Climatology and Geophysical Agency lifted the warning just before dawn, about two hours after the quake.Īuthorities said that based on sea level observations, minor tsunamis of 11 centimeters were detected in Tanah Bala coastal area of South Nias regency. The magnitude 7.1 earthquake was centered 170 kilometres southeast of Teluk Dalam, a coastal town in the South Nias region of North Sumatra, at a depth of 15 kilometres, the US Geological Survey said. “Many residents in several villages on Mentawai island chose to stay … in higher ground although the tsunami alert was ended, due to fears of aftershocks,” he said, adding that authorities were still collecting information about the damage. Residents in parts of West Sumatra province, including the provincial capital of Padang, felt the earthquake strongly for about 30 seconds, disaster agency spokesperson Abdul Muhari said. The shocks were felt in districts and cities of West Sumatra and North Sumatra provinces, and some places ordered evacuations to higher ground.