注水前后储层变化特征及动态建模研究

Study on reservoir variation characteristics and dynamic modeling before and after water injection

针对我国东部老油田普遍进入注水开发后期,其地下储层性质发生明显的变化,影响油田进一步勘探开发的问题,依据岩心分析、录井、测井和分析化验资料,充分结合生产动态开发数据,以孔店油田馆陶组为例,分析了注水前后储层变化特征,建立了不同开发阶段的渗透率动态模型。研究结果表明:1)受到长期注水冲刷及水质的影响,孔店油田馆陶组稳定矿物占比相对增大,不稳定矿物占比相对减小;薄膜状黏土矿物占比相对增大,粒状等多状态黏土矿物占比相对减小;储层孔隙度、渗透率和粒径中值变大,分选系数变小;原油黏度增大。2)建立了开发早期、中期和后期3个阶段渗透率模型。NgⅠ_(3)小层原始储层渗透率整体较高,渗透率高值分布在东部及西北部部分区域。由于新钻井附近注水开发力度加大,使得开发中期中西部区域储层渗透率明显增大,开发后期西北部、东北部及东南部区域储层渗透率明显增大。以上成果对长期注水老油田的后续开发具有指导意义。

In view of the problems that the old oilfields in eastern China have generally entered the late stage of water injection development,and the properties of underground reservoirs have changed obviously,which affects the fur-ther exploration and development of oilfields.Based on core analysis,logging,well logging and analytical laboratory data,fully combined with the production dynamic development data,taking Guantao Formation of Kongdian Oilfield as an example,the characteristics of reservoir changes before and after water injection are analyzed,and the permea-bility dynamic models of different development stages are established.The results show that:1)Due to the influence of long-term water flooding and water quality,the proportion of stable minerals in Guantao Formation of Kongdian Oilfield increases relatively,while the proportion of unstable minerals decreases relatively;The proportion of thin film clay minerals increases relatively,while the proportion of granular and other multi-state clay minerals decreases relatively.The porosity,permeability and median particle size of the reservoir become larger,and the sorting coeffi-cient becomes smaller.The viscosity of crude oil increases.2)Three stage permeability models were established in the early stage,middle stage and late stage of development.The permeability of the original reservoir of small layer Ng Ⅰ_(3)is higher overall,and the high permeability values are distributed in parts of the east and northwest.Due to the increase of water injection development near the new drilling,the permeability of the reservoir in the middle and western regions of the middle stage of development increases significantly.The permeability of reservoirs in north-west,northeast and southeast regions increased obviously in the late stage of development.The above results are of guiding significance to the subsequent development of old oilfields with long-term water flooding.