Evaluation of effectiveness of crystalline basement buried hill reservoirs has long been a difficult geological problem.In this paper

JZ25-1S metamorphosed basement buried hill in Bohai Bay Basin is taken as an example.First

fracture characteristic parameters are studied by using various data such as core

thin section

well logging

production test and experimental analysis.Then

the effectiveness of fractures and matrix in the buried hill reservoirs are evaluated based on the analysis of both dynamic data and static data.The research results show that fractures are highly developed in JZ25-1S and their effectiveness is high.The most effective fractures are open oblique fractures which are formed in later period

followed by the half-filled and full-filled vertical fractures

and the worst fractures are the filled horizontal fractures which are formed in early period.With the characteristics of rock physics

PLT and core centrifuge test

the lower limits of physical properties in buried hill reservoirs are determined.By using static imbibition experiment

it is possible to quantitatively evaluate the development potential of Matrix system.Capillary force is the main driving force for drainage process in matrix blocks.And the main factors influencing drainage process are the distribution and growth level of micro-fractures.