油田开发中后期储层面临的问题与基于沉积成因的地质表征方法

随着中国已开发老油田进入高含水阶段,储层研究的核心发生了一定的转移,重点从优质储层的评价转向影响油藏注采矛盾的层内与平面储层非均质性。层内非均质研究的重点从传统的非均质参数评价转向储层构型研究,即针对不同沉积成因来研究砂体在不同方向上的几何形态与其内部隔夹层的展布特征;而平面非均质的研究则走进了依据储层规模、沉积成因及特点,尤其是岩性特征与其厚度的差异来选择合理的表征参数,并进行成因统计与定量编图的阶段;构成了"微相导向、相序指导、成因量化、平剖结合"的储层表征新方法,以便更好地体现储层表征的功能与作用,即识别不同储集体(对开发而言就是小层或单砂体)自身的成因特征与分布规律并依此来解决油田开发矛盾的作用。功能的核心就是科学地进行成因分类并最大限度地逼近地质的真实,而作用则是预测地下油气的分布规律并为其有效或高效开发提供可靠的系统指导。

Existing problems and sedimentogenesis-based methods of reservoir characterization during the middle and later periods of oilfield development

During the high watercut stage of proven old oil fields in China,reservoir study has changed from the evaluation of high-quality reservoirs to interlayer and plane reservoir heterogeneity which affects the conflict between oil reservoir injection and production.The key issue for interlayer heterogeneity study has transferred from evaluation of traditional heterogeneity parameters to reservoir architecture,where the core of reservoir architecture research is to figure out the geometric shape of sandbodies with different genies and different directions and the distribution characteristics of interbeds;while the core of planar heterogeneity research is to choose scientific and reasonable parameters for accurate calculation and quantitative mapping according to reservoir scale,depositional genesis and characteristics,especially the differences between lithologic characteristics and thickness.All the above formed a new method for reservoir characterization,which can be summarized as "led by microfacies,guided by facies sequence,genesis quantification and integration of plane and profile".It can better reflect the function and effect of reservoir characterization,which was to identify the genetic characteristics and distribution rules of different reservoirs(sublayers or sandbodies in development) to figure out the problems in oilfield development.The function of reservoir characterization is to approach the geological reality in maximum scale by scientific genesis classification,while the effect of reservoir characterization is to predict the distribution rules of subsurface oil/gas and to provide reliable and synthetic guidance for effective development.