英东萨尔图低渗透砂岩油藏单砂体内部相对高渗透段定量识别

Quantitative identification of high-permeability sections in Saertu low-permeability single sand-body reservoir,Jilin Oilfield

通过对岩心分析化验数据分析整理,总结出渗透率极差法、累计渗透率贡献值法、驱动压力梯度法定量求取低渗透储层单砂体内部高渗透段的下限值,3种方法相互验证.强水动力条件是低渗透砂岩油藏单砂体内部高渗透段的沉积成因,后期次生溶蚀孔是其微观成因.高渗透段相渗曲线具有驼背型特点,初期稳定高产,后期水窜.采用贝叶斯判别分析法建立了不同渗透层段的判别函数,进行了非取心井的高渗透段的定量识别,在此基础上,详细描述了高渗透段的空间分布规律,席状砂微相的高渗透段主要发育在单砂体内的中下部,连通性好,分布面积大,长宽比为3∶2;河口坝微相的高渗透段主要分布在中部,长条状分布,长宽比4∶1.结合高渗透段的生产特征,提出封堵高渗透段,扩大波及面积,采用泡沫气驱方式提高采收率.

Based on the analysis of core data,three methods for quantitatively determining the lower limit of permeability of high permeability section in low-permeability single sand body are summarized: range method,accumulative permeability contribution value method and driving pressure gradient method.Three results are verified each other.It is held that strong water dynamic condition is sedimentary origin of the high permeability sections,and secondary dissolution pore is their micro genesis.The relative permeability curves of the high permeability sections are humpback-shaped,and therefore there is high oil yield in the initial period of development and water channeling will occur in the later period of development.The functions for determining high permeability sections were established using Bayes analysis method,and they are used for quantitatively identifying high permeability sections in a non-coring well.The spatial distribution of the high permeability sections is described.The results show that,the high permeability sections of sheet sand microfacies develop in middle-lower part of the single sand body,they are of good connectivity and large area,and their length-to-width ratio is 3∶ 2;the high permeability sections of debouch bar microfacies develop in middle part of the single sand body,they are of long strip shape and their length-to-width ratio is 4∶ 1.According to the production performance of the high permeability sections,the measures for enhancing the recovery factor of Saertu low-permeability single sand-body reservoir are using foam gas flooding and sealing high permeability sections for expanding sweeping area.