Abstract：Foreign geophysicists have offered some examples of various oil and gas fieldswhich are related to negative gravity effect.Theoretical gravity research shows thatthe density difference between saturated oil and water in rock may be -0.3×103~-0.1×103kg/m3,and that the density difference between hydrocarbon reservoir and country rock may be -0.6×103~0.2×103kg/m3.Hence,the high-accurategravimetric survey may lead to the discovery of the hydrocarbon accumulationswhich are related to negative gravity effect.Two examples are given of performing high-accurate gravimetric survey in Xiaermen and Anpeng oil-field areas in Miyang depression.The quantitative gravimetric data interpretation confirms that Xiaermen oil field coincides with negative gravity effect while the minimum negative gravity effect observed in Anpeng oil field is much higher than the theoretical value corresponding to the oil reservoir because the oil reservoir is small,thin and deep.Suchdeviation indicates that there may be other low density bodies in the area.
