【摘要】 对塔河油田奥陶系碳酸盐岩岩溶期次的研究一直处于从未间断和不断更新的状态。通过岩石学、沉积学、地震学等研究表明,塔河油田存在加里东中期第Ⅲ幕岩溶作用。其表现为在桑塔木组顶面发育近南北走向的古河流侵蚀沟谷、志留系覆盖区内桑塔木组地层的残留厚度呈现为北薄南厚等一系列识别标志。该幕岩溶的主要作用层位为中—下奥陶统纯灰岩地层,主要作用区域为西北部古地貌高处,在桑塔木组尖灭线以北地区呈现为暴露风化壳岩溶,以南地区则主要表现为沿断裂发生的岩溶作用。更多还原

【Abstract】 Researches on the karst stage of Ordovician carbonates in the Tahe Oilfield have been ceaselessly renewed.Predecessors considered that there were mainly mid-Caledonian(Episode Ⅰ,Episode Ⅱ) karst and early-Hercynian karst in the Tahe Oilfield.However,through the study of petrology,sedimentology and seismology,this paper concluded that the Episode Ⅲ karst of mid-Caledonian existed in the Tahe Oilfield.The evidence indicated a series of recognition markers,such as there developed a corroded valley of a NS-trend paleo-river at the top of the Sangtamu Formation and the residual thickness of the formation within the Silurian coverage became thinner from southeast to northwest,etc.The main layer and area affected by the Episode Ⅲ were in the middle-lower Ordovician pure limestone stratum and the northwestern paleo-geographic high,respectively.Restricted by an aquifuge of the Sangtamu Formation and the global ice age from the end of Ordovician to early Silurian,this karst was represented by an exposed weathering crust and the karstification occurring along fractures,respectively in the north and the south to the wedge out of the Sangtamu Formation.更多还原