东濮凹陷盐岩地震地质特征研究

东濮凹陷为一典型的盐湖盆地,盐岩与油气成藏关系非常密切,但是盐岩地震反射特征多变,增加了地震岩性预测的难度和不确定性.通过对东濮凹陷盐岩纵横向分布规律的研究,以及对砂、泥、盐岩等地球物理属性的统计分析,落实了砂、泥、盐岩等3种岩性的时空关系和地球物理参数特征.利用正、反演技术明确了盐岩层的地震反射特征除了与密度、速度等参数有关外,还与盐岩层的组合韵律和埋深有关.一般情况下盐岩层具有强振幅、高连续、相对低频的地震反射特征,在盐岩沉积中心厚度较大的特殊情况下,可形成弱反射、较高频、中高连续的地震反射特征.提出在盐岩发育段进行岩性预测宜采用逆向地震储层预测方法,即先将岩盐的分布范围确定下来,然后再进行储层砂体描述.将该方法应用于东濮凹陷多个含盐区块,砂体预测结果与钻井揭示结果相吻合.

Seismogeologic features of halite in Dongpu depression. Pang Shangming

There are four sets of halite related to the reservoirs of Eogene in Dongpu depression. But the changeful seismic reflection of halite increases more difficult and more uncertain to predict reservoir, therefore enlarges the exploration risk and debases the well successful ratio. After studied on distribution of halite and analyzed the geophysical characteristics of sand-rock, mud-rock and halite, their spatio-temporal relationship and geophysical parameters are ascertained. Using the forward and inverse modeling techniques, one is conformed that the seismic reflection characteristics of halite are not only influenced by the density and velocity, but also by stratum rhythm and depth. The paper presented that the seismic reflection of halite is usually strong amplitude, good continuity and low frequency. But it also may be a weak amplitude, middle continuity and high frequency reflection at the salt sedimentary center. At last the author pointed out that it is should use the reverse prediction method in salt-bearing formation to obtain a good exploration result.