玉北地区奥陶系碳酸盐岩风化壳岩溶储层特征及其主控因素

Reservoir characterization and controlling factors of Ordovician weathering crust reservoir in Yubei area,Tarim basin

利用测井解释数据、岩心及薄片观察结果,分析塔里木盆地玉北地区奥陶系碳酸盐岩风化壳岩溶储层特征、分布规律及其主控因素。结果表明:玉北地区奥陶系碳酸盐岩主要发育加里东中期和海西早期风化壳岩溶,鹰山组是风化壳岩溶最为发育的地层。储层垂向分布于水平潜流带高角度溶缝、半充填的溶蚀孔洞、粒间溶孔和晶间溶孔,以及垂直渗流带半充填的高角度溶缝和中小型溶蚀孔洞;储层平面分布于岩溶高地和岩溶斜坡古地貌单元,发育滑塌堆积物、溶洞、溶孔和溶缝等储集空间。研究区裂缝发育,与溶蚀孔洞相互沟通,明显改善碳酸盐岩储层的渗透性能。加里东中期—海西早期构造运动导致的地层长期暴露剥蚀、断裂活动和裂缝发育是风化壳岩溶储层形成的主要原因,东部断裂带鹰山组碳酸盐岩为勘探首选目标。

To analyze Ordovician weathered crust reservoir in Yubei area of Tarim basin,based on logging data,cores and microscope observation,studies of weathering crust reservoir characteristic,reservoir distribution and reservoir controlling factors have been carried out.It is considered that weathering crust developed in middle Caledonian and early Hercynian.Yingshan formation is the best developed weathering crust formation.Reservoir distributed vertically in high-angle solution fissures,half filling dissolution pores,interparticle dissolution pores and intercrystalline solution pores of horizontal undercurrent belts and half filling high-angle solution fissures and small and medium-sized dissolution pores of vertical vadose belts.Favorable reservoirs are mainly distributed in karst highland and karst slope.Large cave collapse breccias,karst cave,dissolved pores and solution fissures are the main reservoir space.Fissures in Yubei area,which are connected with solution pores,are so well developed that they can enhance penetrating quality of carbonate reservoir.Development of long-term exposure and erosion of formation caused by Caledonian-Hercynian tectonic movement,fracture movement and fracture development are the important controlling factors of the weathering crust reservoir formation.Yingshan formation carbonatite of the eastern fault is the favorable exploration area.