Apparent Effective Thickness Prevision through Spontaneous Potential Method and Its Application in Oil Development

The upper spontaneous potential produced by oil and gas accumulation remains with stable potential field. Its intensity is in direct ratio to the content of the source and in inverse ratio to the radius apart from the source. Theoretical researches and practice show that abnormalities of spontaneous potential can indicate oil-bearing sandstone and locate oil-and-gas-enriched area. In oil area which is devoid of sufficient reservoir beds, the thickness of the petroleum reservoir can be predicted by determining the linear relationship between potential intensity and apparent effective thickness. In Weixing field, which is devoid of sufficient reservoir beds, its apparent effective thickness can be predicted by the linear equation. Based on the geological research and by applying spontaneous potential, the effective thickness is predicted for selecting the most appropriate drill sites to increase the possibility of successful well boring for the next round progressive development.