Abstract: The sandstone-conglomerate bodies from short axis source rock of Sha-4 member in west slope belt of Damintun sag have the characteristics of poor sorting,complex reservoir type and great difficulty in effective reservoir recognition.Aiming at the above problems,the research on reservoir types and oil control factor analysis,and the work on "sweet spots" identification by spontaneous potential with poor amplitude have been carried.The results show the low maturity structure and low compositional maturity are the key factors of tight sandstone reservoirs.There exists cracks in reservoirs of the area and the oil-bearing characteristic is controlled by permeability.Poor amplitude in spontaneous potential can better reflect reservoir permeability changes.On the basis of this,the research on reservoir classification and types of sandstone-conglomerate bodies of single well has been carried out and therefore,the classification standard of"sweet spot"in the research area has been established,which provides guidance for exploration in the next step.