轮古西地区碳酸盐岩油藏特征与失利井研究

摘要： 以塔里木盆地塔北地区轮南西部奥陶系碳酸盐岩潜山风化壳油藏为例，通过对工区20多口探井的地质、测井资料以及地球化学分析化验资料的系统分析，研究了轮南西部轮古西地区碳酸盐岩油藏特点、成藏特征以及勘探失利原因。认为轮古西地区奥陶系鹰山组为主要含油层系，油气分布在风化壳面以下180m范围内，以晶间孔、粒内溶蚀孔以及各种构造缝和溶蚀缝为主要储集空间；晚海西期油气充注成藏，之后经历构造抬升，油气遭受强烈生物降解，原油具有高密度、高黏度、高沥青质、高蜡、高含硫、低饱芳比的特征；钻探失利的主要原因可归结为碳酸盐岩储层强烈的非均质性、圈闭的落实程度差、岩溶缝洞体系内复杂的油水分布关系、地震资料解释精度低等。古地貌、岩溶储层、断层是油气富集的主控因素，在深大断裂带附近，古岩溶、裂缝与溶洞发育区，油气产能较高。

Urban Landscape Classification:a Morphological Study Based on Town Plan Analysis

In this paper,the Ordovician weathering crust reservoir in west Lungu region of Tarim Basin is taken as an example.Through the systematic analysis of geological,seismic,logging,and geochemical data derived from more than 20 exploration wells,the carbonate reservoir characteristics and accumulation features of west Lunnan region are studied,and then,the reasons leading to exploration failure are discussed by detailed analysis on the wells.The study shows that in west Lungu region,the Ordovician Yingshan Group is demonstrated as the main oil-bearing formation,in which hydrocarbons are distributed within 180m beneath the weathering crust surface.The reservoir space here mainly includes intergranular pore,intragranular pore,structural fractures and corroded fissures.Hydrocarbons are initially charged and accumulated here as a reservoir in late Hercynian period,then undergone an intense biodegradation due to tectonic uplift,which lead to the characteristics of high density,high viscosity,high-quality asphalt,high wax,high sulfur and low saturated /aromatic of the petroleum.The failure of those wells can be generally summarized as: strong carbonate reservoir heterogeneity,ascertainment of traps and complex distribution of oil-water in the karst fracture-cave system,accuracy of seismic interpretation,etc.The palaeogeomorphology,karst reservoir and fault are critical factors for oil and gas accumulations,high petroleum production usually occurs near discordogenic fault where the fracture and cave are well developed.Therefore,deeper drillings are suggested to be performed in this zone in future.