The Research On Factors That Influence The Velocity Of Low Porosity Sandstone

Low porosity and permeability reservoir has drawn ever-increasing attention in geophysical prospecting.Low porosity sandstone velocity is crucial to seismic inversion,processing and interpretation.This paper has mainly discussed the factors that influenced the velocity of low porosity sandstone using several laboratory tests.The results have shown that these factors include microscopic structure of sandstone and its reservoir characteristics.The newly-designed pressure transducer which intended to be used in ultrasonic test system has stronger signal energy and more detectable preliminary wave under p-t conditions.With this new pressure transducer being used,the accuracy of wave velocity tests had been greatly enhanced.The laboratory ultrasonic test results and rock casting thin section results have shown that the velocity of low porosity sandstone is influenced by pore connectivity,pore type and grain size,etc.It is indicate that the poor pore connectivity,inter-granular dissolved pores and larger grains may lead to a lower velocity.Experimental results indicate that the sandstone velocity is influenced by reservoir characteristics,such as pressure,pore fluid,pore fluid saturation and shale content.Low porosity sandstone velocity shows less pressure sensitivity compared to high porosity sandstone velocity.The P-wave velocity of low porosity sandstone is increased with water saturation.The higher shale content leads the lower velocity of low porosity sandstone.