摘要:
轮古7井区地处轮南古潜山一级地貌单元岩溶高地上,该次研究利用残厚法对研究区岩溶古地貌特征及古水动力条件进行刻画,划分为岩溶高地、岩溶坡地两种二级地貌单元类型,并应用现代岩溶分类方法,根据微地貌组合形态对二级地貌做精细刻画,划分了六种三级地貌单元。通过对岩溶储层展布规律深入研究,认为其储集空间主要为后期构造及岩溶作用所形成的次生溶蚀孔洞、溶蚀裂缝和洞穴系统。根据孔、洞、缝组合特征,及裂缝孔隙度和孔洞孔隙度的物性关系,将奥陶系鹰山组岩溶储层类型划分为裂缝型、孔洞型、裂缝—孔洞型、洞穴型四类。岩溶高地由于剥蚀作用强烈,相对于岩溶坡地来讲后者更易于岩溶储集空间的保存;岩溶坡地地带水动力条件较强,水平径流带岩溶管道系统发育,连通性较好,为洞穴型岩溶储层发育带,易于形成大型缝洞体。
Abstract:
The Tabei uplift of the Tarim basin is one of the three largest ancient uplifts.Lungu7 well block is located in the northern uplift in Lunnan buried hill in the primary geomorphic unit karst highland,high area of Lunnan low raise.It is rich in oil and gas resources,and the Ordovician carbonates are one of the richest oil-bearing series,and one of the main formations for exploration and development.The different geomor-phic units control the ancient hydrodynamic conditions,and further determine the diversity of karst develop-ment.Therefore,the precise shape of the karst paleogeomorphology is of great significance for the reasona-ble arrangement of high production and efficient wells.
This study uses the relative residual thickness method to characterize ancient karst landforms and ancient hydrodynamic conditions.Two types of secondary geomorphic unit are classified,karst highland and karst slope.Furthermore,six types of tertiary geomorphic unit are classified after the precise description of the secondary geomorphic unit on the basis of combinations of micro-geomorphologic landforms.
Through further research on the karst reservoir distribution pattern,this study considered that the res-ervoir volume is mainly comprised of secondary solution pores,corrosion cracks and cave systems,formed by later structure and karstification.According to the combined characteristics of the holes,caves and seams,as well as the relationship between fracture porosity and hole porosity,the Ordovician Yingshan karst reser-voirs are divided into four types,fracture,hole,crack-hole,and cave.
Compared to karst slopes,karst highlands more easily preserve karst reservoir space due to stronger de-nudation.The karst slope zone easily forms a large fracture-cave cube because of it strong hydrodynamic con-ditions,well-developed karst piping system and good connectivity.It can be treated as karst cave reservoir, which provides the basis for future exploration and development.
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