东濮凹陷东营组地层剥蚀厚度估算及其意义

判断能否运用声波时差法进行地层剥蚀厚度估算的标准应该是依据抬升剥蚀前地层的压实效应是否被后来的沉积地层所改造;在适当的条件下,声波时差法也可能适用于地层沉积厚度过补偿的情况.综合利用镜质体反射率和声波时差测井资料对东濮凹陷单井的东营组地层剥蚀厚度进行了计算.通过对多口井的东营组残余地层厚度与地层剥蚀厚度之间的关系分析,绘制了东濮凹陷东营组地层剥蚀厚度等值线图.结果表明,构造部位不同,东营组地层剥蚀厚度也不同:从凸起(或边缘隆起)-斜坡-凹陷中心,地层剥蚀厚度顺次减小;洼陷中心及斜坡部位,新近纪以来沉积过补偿厚度较大,沙四上亚段-沙三中亚段烃源岩自新近纪以来发生了二次生烃过程,二次生烃和晚期成藏的油气就近发生聚集,并得以有效地保存,预示着东濮凹陷环洼斜坡深层仍具有较大的油气勘探潜力.

Calculation of the Erosion Thickness of Dongying Formation in Dongpu Depression and Its Significance

The calculation of erosion thickness by sonic time difference should depend upon whether the compaction of the previous formations before uplift and erosion has been transformed by the later depositions. Sometimes, sonic time difference can be used in the circumstances with over compensation thickness. This paper describes the calculation of the erosion thicknesses of Dongying Formation in single wells based on the vitrinite reflectance and sonic time difference data. It also analyses the relationship between residual thickness of the formation and erosion thickness, and then constructs of the contour map of erosion thickness for the formation. The results indicate that the erosion thicknesses vary with tectonic positions and decrease from uplift or marginal rise, slope to sag centers. The Es3-Es4 source rocks of sag centers and slopes have experienced secondary hydrocarbon generation since Neogene, for the large over compensation thickness. The oil and gas formed in the secondary hydrocarbon generation are accumulated nearby and preserved effectively. It is forecasted that there still exists good exploration potential in the deep and circulated area of sub-sags in Dongpu Depression.