鄂尔多斯盆地陇东地区延长组中上段沉积相及砂体预测:基于地震属性的约束OACHSSCD

The Yanchang Formation in the Ordos Basin is an important interval for continental tight sandstone reservoir exploration in China.In the slope zone of the Longdong area,sand bodies are characterized by complex genesis,rapid lateral variation,and high prediction difficulty.Previous studies relying on drilling and logging data,constrained by well points,have insufficiently understood the progradational structures and deep-water sand body distribution.This study integrates 3D seismic,drilling,logging,and core data,and employs methods such as well-seismic integrated sequence division and seismic attribute analysis to systematically investigate reservoir sand bodies and sedimentary facies characteristics.The results show that in the middle and upper Yanchang Formation,the lake basin transitioned from deep-water undercompensated deposition to delta progradation.Seismic attribute analysis effectively constrains the spatial distribution of sand bodies:the gentle slope zone develops delta front underwater distributary channel and mouth bar sand bodies;the slope zone is dominated by muddy deposits with locally developed slump or gravity-flow sand bodies;and the foot of the deep-water slope break zone to the depression zone is the enrichment area of deep-water gravity-flow sand bodies.Accordingly,a sedimentary model of"gentle slope zone delta front sand bodies-slope zone muddy deposits-depression zone gravity-flow sand bodies"is established.The introduction of 3D seismic data significantly improves the accuracy of sand body characterization in the slope zone,providing a basis for lithological reservoir exploration in the deep-water to semi-deep-water areas of the Yanchang Formation.