计算剥蚀厚度的优化孔隙度法:程序及应用

Optimum Estimation of the Thickness of Erosion by Porosity Data: Program and A Case

碎屑岩 (泥岩和砂岩 )在正常压实埋藏过程中 ,原始孔隙度的演化随埋深的增加呈指数减小。利用在深度zi 处的孔隙度实测值Φi 及其理论值Φ ,考虑m次观察中的误差平方和 ,找到最有可能使得该误差平方和达到最小的原始孔隙度Φ0 及地层的剥蚀厚度h。对地层剥蚀厚度的一种新的计算方法—优化孔隙度法的原理作了简单介绍 ,并给出了实用的计算机应用程序和应用实例 ,还就本方法应用中的问题进行了简单的讨论。

A new approach is briefly introduced for the optimum estimation of the thickness of erosion using primary porosity data. There are two keys that should be considered in this method: (1) the porosity data must be primary; (2) the porosity on the ground surface is not a fixed constant, but a variable changing with the sedimentation condition and other factors. In this paper we deal with these two aspects separately. For the former, we revise the porosity based on study of diagenesis. For the latter, optimum statistic principle is used. The method is applied to both the mudstone and sandstone from Mingshui Formation of Changling Depression in southern Songliao Basin. Both two estimations yield a similar result of about 500 m of erosion by using computer program. Considerations that should be taken into account in geological application are also discussed in this paper.