Characteristics of Metamorphic Rock Reservoirs and Its Influencing Factors on Chengbeigu 7 Buried Hill in Chengdao Oilfield

Chengbeigu 7 buried hill is strike slip thrust structure, developed under the strike slip extrusion of the basement of the eastern fault basin during orogenic period in Chengbei low uplift fracture zone of Chengning uplift belt in Bohai Bay Basin. The strata of buried hill consist mainly of metamorphic rocks, dominated by granitic gneiss. Due to the multi phase tectonic movement and weathering alteration, excellent reservoirs with pores and fractures are well developed. However, this set of reservoir is serious in heterogeneity, with complex lithology, and mixed metamorphic crystallization has occurred commonly. In this study, by using the rich core and electric imaging logging data which obtained during the process of reservoir development, study has been conducted on the characteristics of metamorphic rock, the reservoir physical properties and the types of reservoir space. Through study of the structure characteristics and interwell correlation, analysis has been finished on the reservoir planar distribution, vertical development and the influence factors. The metamorphic rocks have granoblastic texture, gneiss structure. Reservoirs are rich in fractures and karsts, with planar difference and vertical partition, and the crack development was significantly affected by structure and tectonic stage.