四川盆地东部黄龙组古岩溶地貌研究

作为川东地区最重要的天然气储集类型之一的石炭系黄龙组古岩溶型储层,业已引起众多油气地质工作者的重视。通过古岩溶作用标志识别和成因分析,采用残余地层厚度法、地貌法和印模法等技术手段对川东地区黄龙组古岩溶地貌进行恢复,从中划分出岩溶高地、岩溶斜坡和岩溶盆地三个岩溶地貌单元和峰丛、溶沟、落水洞、坡地、谷地、浅洼、残丘和槽地等微地貌单元,在平面上细分出七个典型的古岩溶地貌分区,并对分区内的岩溶地貌特征进行了研究,认为不同古岩溶地貌分区所处的地理位置及微地貌单元组成特征具有明显差异,从而直接影响到天然气藏的发育。在此基础上,对川东地区古岩溶及储层发育控制因素进行了分析,认为构造、气候、岩性、层位、古地形、古水文条件和不同的岩溶地貌形态影响和控制着古岩溶储层的发育与区域分布。上述研究成果将为川东石炭系古岩溶型储层评价与有利区带优选提供可靠依据。

Study on the Carboniferous Palaeokarst Landform in Eastern Sichuan Basin

A number of geological workers take it seriously that palaeokarst reservoir in the Huanglong Formation of Carboniferous are the most important types of natural gas reservoir.Through the sign recognition and the causes analysis of karstification, palaeokarst landform in the Huanglong Formation of Carboniferous is resumed with the erosion thicknesses method, geomorphologic method and impression method in eastern of the Sichuan Basin. The karst morphological unit, such as karst highlands, karst slopes and karst basin and the minor morphological unit, such as peak cluster, ponor, hillsides, valley, shallow depression, remnant hills and trough valley are subdivided. The seven subareas of palaeokarst landform are subdivided in the area of the east Sichuan Basin, and the karst morphological characteristics is studied in different subarea. It is considered that the geographical location of palaeokarst landform and the characteristics of karst morphological unit have significant differences and a direct impact on the formations of gas fields.On this basis, the palaeokarst reservoirs development controlling factors in eastern Sichuan Basin are analysed and it is put forward that structure, climate, lithology, strata, ancient terrain, hydrogeologic conditions and different karst morphological forms influenced or even controlled the development and regional distribution of palaeokarst reservoirs.So the research findings will provide reliable evidence for the palaeokarst reservoirs evaluation and favorable area optimization.