RECOGNITION OF SAND-GRAVEL BODY AND FORECASTING ITS PETROLEUM-BEARING FEATURE IN NORTHERN STEEP SLOPE OF CHEZHEN SAG

Sand-gravel body of Es3x in the northern steep slope of Chezhen sag are well developed, but their spreading range and boundary are not obvious, and the distribution of effective reservoirs are not affirmative either. Due to above conditions of the research area, the authors first block out the sediment facies of the sand-gravel fan by using coherent analysis technique and affirm the spreading range and boundary of the sand-gravel fan. Then they discuss the Es3x pressure of the research area by using sound wave data and velocity spectrum data, believing there exists under-compaction hyper-pressure zone in Es3x in the research zone. At last the authors forecast the petroleum-bearing feature of the sand-gravel body by using techniques of attenuation gradient of seismic energy. The favorable petroleum-bearing zone forecasted by techniques of attenuation gradient of seismic energy is located in under-compaction hyper-pressure zone. Techniques of attenuation gradient of seismic energy not only forecast the petroleum-bearing feature of the well, but can be used as step-out evidence of the oil field. The conformity of petroleum-bearing feature between the results forecasted by techniques of attenuation gradient of seismic energy and by the drilling results is good.