克拉通盆地微古地貌恢复的构造趋势面转换法

发布时间：2019-02-21 12:31

【摘要】：为推算克拉通盆地弱构造变形区海相沉积期微幅度古地貌,提出了一种基于构造趋势面转换的沉积期微幅度古地貌推算方法。方法假设克拉通盆地的多阶段升降或扭转构造运动表现为构造趋势面的变动,但该变动并没有改变局部古高地与其周围地形的拟构造幅度。该方法的技术流程为,首先利用现今构造图及其趋势面求得拟构造幅度;然后将地层剥蚀线的平均走向近似于沉积期构造趋势面的走向,求得沉积期构造趋势面倾向;利用将今论古的思想借用现今潮坪相平均坡度作为沉积期构造趋势面的倾角;最后将沉积期构造趋势面与拟构造幅度相加即得沉积期古地形图。在此基础上,结合取心井的岩石学、白云石化类型,可以更好地确定海相沉积体系中各亚相或微相的分布范围。将此方法应用于苏里格气田东区下奥陶统马家沟组五段5亚段潮坪相碳酸盐岩地层的应用效果表明,研究区构造趋势面由NW—SE倾向变动到NE—SW倾向,其并没有改变沉积期局部古地貌与其周围地形的相对高低关系,该方法能够有效地刻画出潮坪相沉积期微幅度古地貌。沉积期水下微幅度古地貌隆起部位是控制该区潮坪相碳酸盐岩颗粒滩分布的关键因素,颗粒滩又是后期白云石化并发育为优质储层最有利的微相。因此,在准确刻画沉积期微幅度古地貌的基础上可以发现高产气井。该方法可以为其他克拉通盆地弱构造变形区沉积期古地貌研究提供有益的思路。
[Abstract]:In order to calculate the micro-amplitude paleogeomorphology of marine sedimentary period in weak tectonic deformation area of craton basin, a method of calculating micro-amplitude paleogeomorphology of sedimentary period based on structural trend surface transformation is proposed. Methods it is assumed that the multi-stage uplift or torsional tectonic movement of the craton basin is the change of the tectonic trend surface, but this change does not change the pseudotectonic amplitude of the local paleohighlands and their surrounding topography. The technical flow of this method is as follows: firstly, the pseudotectonic amplitude is obtained by using the present tectonic map and its trend surface, then the average strike of the strata denudation line is approximated to the strike of the sedimentary tectonic trend surface, and the tendency of the sedimentary tectonic trend surface is obtained. The present thought of ancient times is used to use the average gradient of the present tidal flat facies as the dip angle of the sedimentary tectonic trend surface, and finally the sedimentary paleotopographic map is obtained by adding the sedimentary tectonic trend surface with the pseudotectonic amplitude. On this basis, combining the petrology of coring wells and dolomitization types, the distribution range of subfacies or microfacies in marine sedimentary system can be better determined. The application of this method to the Chaoping carbonate strata of the 5th member of the Lower Ordovician Majiagou formation in the eastern part of Sulige gas field shows that the tectonic trend surface of the studied area has changed from NW-SE tendency to NE-SW tendency. It does not change the relative relationship between the local paleogeomorphology of sedimentary period and its surrounding topography. This method can effectively depict the micro-amplitude paleogeomorphology of tidal flat facies during sedimentary period. The subaqueous micro-range paleogeomorphic uplift is the key factor to control the distribution of tidal flat carbonate granular beach, which is the most favorable microfacies in late dolomitization and developed into high quality reservoir. Therefore, high-yield gas wells can be found on the basis of accurately depicting the paleogeomorphology of the sedimentary period. This method can provide useful ideas for the study of sedimentary paleogeomorphology in weak tectonic deformation areas of other craton basins.
【作者单位】：中国石油大学石油工程教育部重点实验室;中国石油长庆油田公司第五采气厂;
【基金】：中国石油大学(北京)科研基金项目(2462015YQ0222)资助
【分类号】：P618.13;P531

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