Research progress and prospect of Ordovician carbonate rocks in Tahe oilfield: karst feature

Inspired by structural geology, karstology, geomorphology, as well as petroleum geology, coupling excellent documented research works and the field investigation, the status and prospect for the studies on karst feature of Tahe oilfield are discussed comprehensively. Results indicate: (a) the majority of research works have appeared since 2000 and can be classified as three categories and 12 subclasses, in which caves, fracture cave systems and fault-karst reservoirs are considered as the main research topics, (b) existed studies can be divided into four stages, and fault-karst reservoir analysis is a hot spot recently, focusing on the scale of the formed reservoir. It is the common sense that faults control both fractures and caves. Originally, there exist close relationships among karst phenomena whether they're on the ground or underground. Revealing these relationships mentioned above is the important direction for the studies of Tahe oilfield in the future. As for the areas where faults are widely distributed in karst, there exist hierarchical properties in karstology: (1) fault controls topography and landform, (2) fault, topography and landform control the water system and (3) fault, topography, landform and water system control karst. These hierarchical properties are the basic connotation of the laws for karst evolution, and the vital goals of the karst study of Tahe oilfield as well. Applications of methods and techniques and field-karst investigation are the solid guarantees to achieve these goals.