塔里木盆地玉北地区奥陶系储层成因及分布

Origin and distribution of the Ordovician carbonate reservoir in Yubei area, Tarim Basin

基于岩心观察、薄片鉴定、成像测井及物性等资料,结合地球化学分析,塔里木盆地玉北地区奥陶系岩溶储层具有明显的"上下分层、东西分异"特征。纵向上储层可以分为3套,分别为表层(以鹰山组上段为主)、鹰山组下段和蓬莱坝组,表层储层储集空间以裂缝型为主,鹰山组下段以裂缝-溶蚀孔洞型为主,蓬莱坝组则以溶蚀孔洞型为主。平面上储层特征具有明显差异,东部断褶区的断裂带,储层发育,以裂缝型为主,东部断褶区的断洼区、中部平台区及西部斜坡区,储层相对较差。纵向上按成因分类,将储层划分为2种类型:表层风化壳岩溶型和内幕断控岩溶型。建立了玉北地区储层发育地质模式。表层风化壳岩溶储层主要分布在南部斜坡区、中部平台区、东部断褶区的断裂带、西部斜坡区罗斯2井区的断裂带等古构造高部位,断控岩溶储层主要沿规模断裂分布。指出中部平台区为下一步有利勘探区带。

The Ordovician reservoir has a good potential for oil and gas exploration in Yubei area,Tarim Basin.Based on the cores,thin sections,imaging logging,physical property data,and geochemical data,the karst reservoirs of Lower-Middle Ordovician in Yubei area have obvious features of"stratification from upper to lower and differentiation from east to west".Longitudinally,there are three sets of reservoirs:the upper section of Yingshan Formation,mainly fracture type;the lower section of Yingshan Formation,mainly fracture-vug type;and the Penglaiba Formation,mainly vug type.Horizontally,the reservoirs developed in the eastern fault zone,mainly fracture type,while it is relatively poor in the central and western regions.According to the palaeo-geomorphology and fracture evolution,the Ordovician reservoir can be divided into two genetic types:weathering crust karst reservoir,mainly distributed in the high parts of palaeo-structures,and fault-controlled karst reservoir,mainly distributed along larger scale fractures.The model of Ordovician reservoir is established in Yubei area,by which the central platform of Yubei could be the next favorable play.