Title: Investigation of the Early Hercynian Paleokarst in Block 12 of Tahe Oilfield,Northern Tarim Basin
Abstract: It has been investigated in this paper that karst occurred in Block 12 of Tahe Oilfield during early Hercynian stage where unconformity interface exists between lower Ordovician carbonate and lower Carbonic Bachu Formation bearing identification features including an existance of collapsed breccias and subsurface stream,differential properties of Sr/Ba ratio filled in caves,which was obtained through the latest research on sedimentology,seismology,geochemistry.The karst paleotopography can be divided into four units: karst highland,Ⅰ-and Ⅱ-karst slope,karst basin,according to which the study area grew in Ⅱ-karst slope.As for the characteristics of pulse-type uplift in early Hercynian stage,three karst cycles occur in the investigation region,where Ⅱ-and Ⅲ-cave stratigraphy grew chiefly.The karst zone predominately covers beyond the pinch-out line of upper Ordovician Sangtamu Formation to the north in plane surface,while it occurs in pure carbonate of mid-lower Ordovician vertically.Karst within this stage was not only controlled by paleotopography and fracture essentially but was the key to the fracture and corrosive caves formation affecting reservoir capability of accumulation and permeability.Finally,an engendering model during early Hercynian stage can be established which can be divided into three phases in terms of developing process: rapidly uplifting and eroding phase,three scene uplifting phase and declining phase.
Publication Year: 2013
Publication Date: 2013-01-01
Language: en
Type: article
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Cited By Count: 1
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