Application of oil and gas detection technology for lithological targets in Qiongdongnan Basin
The Y target in the ultra deep water area of Qiongdongnan Basin is a high-level delta underwater distributary channel sedimentary reservoir controlled by multi-level fault steps.The gas and water layers revealed by drilling data are both shown as"bright spots"in seismic data and have Class Ⅲ AVO features with amplitude enhancement along offset.Conventional oil and gas detection results based on amplitude information have multiple solutions.Therefore,a seismic full information hydrocarbon detection technology that fully utilizes the amplitude,frequency,and phase information of seismic data is proposed.Firstly,this paper comprehensively analyzes the post-stack and pre-stack seismic response characteristics of sandstone reservoirs and influencing factors via seismic forward modeling.It is pointed out that poro-sity and gas layer thickness are the main reasons affecting fluid identification by using amplitude information and proves that thick gas-bearing sandstones can be identified based on amplitude information.Secondly,the seismic reflection spectrum analysis shows that the attenuation of seismic waves caused by hydrocarbon layers is the main reason for the decrease in the main frequency and bandwidth of gas reservoirs.Finally,numerical simulation shows that both thick gas sand and thin gas sand under the background of water layers exhibit obvious absorption and phase anomalies,so the fre-quency and phase information related to seismic wave attenuation can be used for oil and gas detection.The application in the research area shows the proposed method can effectively distinguish between gas and water layers.The detection results are consistent with the actual drilling results,and provide a reliable basis for drilling implementation as well as effectively reduce exploration risks.
Qiongdongnan Basin deltalithological targetAVOformation absorptionwavelet phaseoil and gas detection
万方数据
维普
