Abstract:

Turbidite sandbody reservoir of the Shasan intermediate member at the Niuzhuang sag of Dongying in Shandong Province， mainly consists of feldspathic packsand，litharenite and silstone with low compositional maturity and textural maturity. An investigation for micoscopic reservoir characteristics shows that the type of the reservoir pore space include primary pore， micro-pore of clay mineral matrix，intergranuIar dissolution pore，intragranular dissolution pore and micro-fissure，and the pore structure is mainly characterized by low permeability-fine throat，and that the reservoir have medium-low porosity and
low permeability and poor physical properties. Through the study on the factors which affect the reservoir physical properties，the authors of this paper think that rock composition and texture，sedimentary micro-facies，diagenesis and the generation and distribution of the abnormal high pressure systems are the main factors to control the reservoir physical properties.The carbonate cement，siliceous cement and authigenic clay mineral are the main causes of the poor physical properties; The dissolution of organic acid produced in wide hydrocarbon generation and transformation of clay minerals may produce substantial secondary porosity in reservoir，and the existence of the abnomal high pressure，high geothermal field and early hydrocarbon invasion are a crucial requirement for partial original porosity and secondary porosity to be preserved.

Key words: turbidite sandbodies, reservoir characteristics, diagenesis, abnormal high pressure, the Niuzhuang sag, the Dongying, Shangdong Province