CHARACTERISTICS AND CONTROLLING FACTORS OF GRANITIC BURIED-HILL RESERVOIR IN PL OILFIELD OF BOHAI SEA

As the largest buried-hill oilfield in the Bohai Sea,the PL oilfield is characterized by its porous fractured granitic reservoir. Using the lithological and logging data from wells,the lithology,spatial distribution pattern and physical properties of the reservoir are carefully studied. According to its density and weathering intensity,the reservoir may be divided into several zones,namely,the very strong-weathered,strong-weathered,sub-weathered and weakly-weathered zones in a vertical direction. Comparison of various seismic attributes and drilling records indicates that there exists a high linear relationship between the maximum trough amplitude attribute and the reservoirs,upon which the reservoir spatial distribution were predicted. Furthermore,we discussed the influence factors based upon lithology,tectonic stress,geomorphology and other factors on the evolution of buried hill reservoirs. The study lays the foundation for searching high quality reservoirs and provides a clue for exploration of similar buried hill reservoirs.