千米桥古潜山岩溶地貌演化及古岩溶洞穴发育特征

运用印模法和残厚法以及地震相位追踪对比等古地貌分析法研究揭示,千米桥古潜山岩溶地貌的演化形成先后经历了加里东—海西暴露发育期、印支—燕山暴露改造期、喜马拉雅埋藏定形期等演化阶段。古岩溶洞穴的发育和分布不仅受地貌形态及潜水面的控制,而且与岩性组合、古水文环境及断裂构造密切相关。加里东—海西暴露期地壳的持续抬升和区域潜水面的不断下移,造成古岩溶洞穴的多旋回层状分布,孔洞多被砂泥质充填,有效孔洞保存较少;印支—燕山暴露期发育的古岩溶洞穴受断裂体系影响,分布具有一定随机性,并且多被埋藏期化学半充填,成为目前古潜山油气储层的主要储集空间。利用钻井和测井信息及洞穴充填物,可在生产现场识别古岩溶洞穴的存在及分布,为古潜山油气储层的综合评价提供依据。

Evolution of Karst Paleogeomorphology and Development Features of Paleokarstic caves in the Qianmiqiao Buried Hill in Huabei Oil Fields

By the "moldic" and "residual thickness" methods and the seismic phase tracing and contrasting,the karst paleogeomorphology is analyzed to the Qianmiqiao Buried Hill in Huanghua Depression,Bohaiwan Basin.It is revealed that karst geomorphic of Qianmiqiao buried hill had successively experienced three evolution stages including the exposure and development during Caledonian-Hercynian period,the exposure and reformation during Indosinian-Yanshan period and the sinking,burial and formation during Himalayan period.The development and distribution of palaeokarst caves are not only under control of the geomorphic form and ground water surface,but also are closely related with the lithologic combination,palaeohydrologic environment and fractures.Accompanied with the continuous uplifting of the crust and the unceasingly descending down of regional water table during Caledonian-Hercynian period,palaeokarst caves evolved into multicycle bedded distribution with arenaceous fulling in pores and little available pores preserved.Influenced by fracture system,the palaeokarst caves were distributed with certain randomness and most of pores were partly filled with chemical matters during the Indosinian-Yanshan period.These caves and pores are the present significant reserving spaces for oil and gas in the buried hill.By using drilling and well logging information and cave fillers,the existence and the distribution of the palaeokarst caves may be distinguished,which can provide some information for the comprehensive reservoir evaluation to buried hill reservoirs in oil and gas fields.