Paleocave architectures and controlling processes of the Ordovician carbonate paleokarst systems in western and central Tarim Basin, northwestern China
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引用次数: 0
Abstract
The paleokarst systems of the Ordovician carbonate rocks in the Tarim Basin, northwestern China, comprise economically significant oil and gas reservoirs and display complex cave architectures. Based on comprehensive analysis of seismic, well log, core, and outcrop data, the cave architecture and controlling processes of the Ordovician paleokarst systems in the western margin and central uplift belt of the basin are documented. Cave fills of the paleokarst systems are composed mainly of collapse breccias, crackle or mosaic breccias, chaotic breccias, terrestrial sediment fills, and calcareous muddy deposits. Primary architectural elements of the paleokarst systems include surface collapse caves or pits, fractured roofs and walls, sinkholes and associated small-scale caves, cave-level or fault-cave complexes, fractured layers with fractured pores or cavities, and densely spaced small cavity layers. The paleokarst cave structures are characterized by the development of multiple phreatic cave-level or fault-cave complexes and were constrained mainly by the interplay of changing phreatic zones due to multiple stage uplifts or relative sea-level falls and existing high-angle fault belts. They were also transformed by karstification with composite unconformities and hypogenic process. The paleokarst system in the central uplift belt formed in a carbonate island environment during the late Middle Ordovician, whereas the system in the western basin margin developed in an attached carbonate platform setting at the end of the Late Ordovician. Partially filled cave-level or fault-cave complexes, fractured cave roofs, or fractured intervals with fractured pores or cavities comprise the most significant reservoirs in the paleokarst systems.
期刊介绍:
While the 21st-century AAPG Bulletin has undergone some changes since 1917, enlarging to 8 ½ x 11” size to incorporate more material and being published digitally as well as in print, it continues to adhere to the primary purpose of the organization, which is to advance the science of geology especially as it relates to petroleum, natural gas, other subsurface fluids, and mineral resources.
Delivered digitally or in print monthly to each AAPG Member as a part of membership dues, the AAPG Bulletin is one of the most respected, peer-reviewed technical journals in existence, with recent issues containing papers focused on such topics as the Middle East, channel detection, China, permeability, subseismic fault prediction, the U.S., and Africa.