琼东南盆地二号断裂带坡折区速度研究进展

PROGRESS OF RESEARCH ON QIONGDONGNAN BASIN SLOPE FAULT ZONE VELOCITY

琼东南盆地二号断裂带是构造分区的标志性断层之一,该断裂带下降盘为中央凹陷带。区域研究表明中央凹陷带具有良好的生烃潜力,所以该区带一直被认为是有利的油气勘探区带。但是由于该区带水深剧烈变化,多期坡折带快速推进沉积形成大套泥岩,使得该区带的速度很难确定,所以速度问题成为制约着琼东南盆地坡折带勘探的难点问题。笔者首先分析现有速度谱的质量,了解速度整体变化趋势;其次考虑已钻井的速度分析结果;结合地震剖面地层的变化信息进行速度解释,采用解释能量团中心的标准进行速度解释;最后在精细速度解释的基础上,对二维剖面正演模型速度进行分析,建立速度体,证实构造目标的存在。

Qiongdongnan basin fault zone is one of the marker faults for fauh partition and one of the central depression downthrown fault zones. Regional studies show that the central depression has a good hydrocarbon potential, so the area has been considered to be a favorable oil and gas exploration area. However, due to the formation of large sets of deposited shale resulting from drastic changes and rapid progress of water depth and slope, it is difficult to determine the velocity in this area, so the velocity problem constrains the exploration of the slope break in Qiongdongnan basin and becomes a difficult problem. In this study, the authors first analyzed the quality of the speed spectra available so as to understand the overall variation trend of the velocity, followed by considering the velocity obtained by drilling results; in combination with stratigraphic variation information, the velocity interpretation was carried out, and the energy in the center was used to explain the standards of velocity interpretation. Finally, on the basis of careful velocity interpretation, the forward model of two-dimensional velocity profile analysis confirmed the existence of a target structure.