摘要
在盆地模拟中,利用“回剥”技术恢复古埋深,关键在于确定地层古孔隙度演化关系式。确定古孔隙度的传统方法(等效深度法)仅适用于无间断匀速沉积的地层,对于埋藏史复杂的地层计算结果误差较大。为此,提出同时考虑地层埋藏时间和埋藏深度对孔隙度演化的影响,即采用孔隙度埋藏时间、孔隙度埋藏深度关系式作为计算孔隙度的函数,并利用数值积分法,计算出地层的骨架厚度值,然后利用回剥技术,计算地层古埋深。在进行数值积分时,可以根据研究精度的需要,确定合适的步长。此方法在东营凹陷的应用表明,计算结果的准确度、可信度要高于传统的计算方法。
The key to restoring the paleoburial depth of the strata in a basin is to get the
accurate paleoporosity of the strata. Backstripping process has become a comparatively good
technique to restore the paleoburial depth of strata in a depositional basin. It has been known
that the age of a stratum has an influence on the evolution of its porosity. Due to various
reasons, for a long time, even nowadays the variation of porosity as a function of strata's
depth, which is called the equivalentdepth method, has still been used to get the paleoburial
depth of a stratum. In the paper, the relationship simultaneously considering the effects of age
and burial depth of a stratum on the evolution of its porosity has been presented to obtain the
paleoburial depth, a reasonable algorithm is proposed in backstripping process. The
application in Dongying depression shows that there is a relatively apparent difference between
the results of using the presented relation and that of using traditional method. The eroded
thickness of Dongying formation is got by means of geometric mapping. The effect of extra
pressure and diagenesis on the evolution is not included. If a stratum in a certain basin is
buried deeply and under a apparently extra high pressure and/or has experienced lots of
diagenetic changes, the calculated paleoburial depth of the stratum may deviated from the real
one and should be further modified.
出处
《石油勘探与开发》
SCIE
EI
CAS
CSCD
北大核心
1999年第3期33-35,共3页
Petroleum Exploration and Development
关键词
沉积盆地
地层埋藏史
构造演化
Basin numerical simulation, Formation, Burial
history, Paleoburial depth, Porosity