塔里木盆地轮南地区奥陶系潜山古岩溶及其所控制的储层非均质性  

Burial Hill Palaeokarst and Its Controlled Reservoir Heterogeneity in Ordovician, Lunnan Region of Tarim Basin

作　　者：郭建华[1] 

机构地区：[1]江汉石油学院

出　　处：《沉积学报》1993年第1期56-64,共9页Acta Sedimentologica Sinica

摘　　要：低孔低渗的碳酸盐岩通过长期的地表风化淋滤、溶蚀之后可能会成为较好的油气储集岩体。本文通过钻井、测井及岩心等资料探讨轮南地区奥陶系灰岩中的古岩溶及其对储集的控制作用。研究表明,区内古岩溶主要形成于早石炭世,岩溶作用所形成的角砾岩相是重要的储集岩类,无论是在横向上或垂向上这种储集岩体均表现出强烈的非均质性。Lunnan region locates in the southern part of Luntai County, belongs to the first class tectonic unit-Tabei rise belt in Tarim Basin. The top of the deep burial Ordovician carbonate rocks occurs in a NE- SW large burial hill. Ordovician System region only remained Upper Qiulitake Group of Lower Ordovician as a result of long-time surface exposition and intense weathering-denudation in Palaeozoic Era. Therock types are mainly the limestones formed in shallow water carbonite platform, which is one of the important oil-gas layers in this region. Many of the exploration wells have revealed that all of the oil-gas layers are distributed at 0-200m interval of the top of Upper Qiulitake Group. The rock cores of about 2000m long show that the palaeokarst is one of the important factors in controlling the development of reservoir. The palaeokarst is well-developed and characteried by clear vertical zonation at the top of Ordovician. From unconformity interface downward, the palaeokarst is divided into the following three zones: 1) surface karst zone, 2) transitional zone and 3) horizontal underground flow zone. Dissolved furrows, cracks and dolines are developed in zone 1; dissolution is not obvious in zone 2; large horizontal caves with the diameter up to 100m vertically, are developed in zone 3. The third zone feature is the most striking within this region. The overwhelming majority of the caves are filled. According to their features, four types of cave-fill deposits are identified: 1) debris flow, 2) underground river, 3) cave roof collapse and 4) gravitational sliding-dilapidation. The deposits in the horizontal caves are composed by the alternated sediments of debris flow, underground river and cave roof collapse. The filling deposits in the surface dissolved cracks and dolines are resulted from the sediments of debris flow and gravitational sliding-dilapidation. Sporo-pollen analysis in the cave-fill deposits shows that all of the sporoes are formed in Early Carboniferous. It can also be deduced from the

关 键 词：古岩溶 储层 非均质性 奥陶纪 

分 类 号：P642.25[天文地球—工程地质学]