摘要
注采模式优选对缓解厚油层层内矛盾,提高纵向波及效率具有重要意义。目前尚未形成油水井同时部分打开的井间解析渗流模型,无法支撑厚油层波及特征的研究。为此,采用保角变换方法,将油水井同时部分打开剖面地层依次变换为圆形边界偏心裂缝井地层、单位圆形边界两分支裂缝井地层、注水井全部打开采油井部分打开剖面地层,之后重复上述变换,将注水井全部打开采油井部分打开剖面地层变换为油水井全部打开剖面地层,从而将原始二维渗流过程变换为一维渗流过程,实现了不同注采模式下厚油层层内压力及流线分布的解析计算。与精细数值模拟方法的对比表明,该方法对不同井距/厚度比的情形均可获得较高计算精度。利用该方法,开展了注采模式对纵向波及特征的研究。结果表明:对于底注高采模式,注水井顶部为主力注入层段,注水井顶部1/3的井段控制超过1/2的地层,使超过2/3的采油井段受效;注水对地层的波及主要作用于注水突破前的阶段。在相同的打开厚度下,底注高采的注水突破最晚、波及效率最高,底注中采、中注高采次之,高注高采、底注底采注水突破最早、波及效率最低。采油井的打开厚度越大,注水突破时间越短,但注水突破时的波及系数增大,应综合考虑注水突破时间和波及系数两方面的因素,优选最佳打开厚度。
The optimization of injection-production modes is of great significance in alleviating intra-layer contradiction and improving longitudinal sweep efficiency for thick reservoirs.The analytical flow model of both producer and injector partially penetrating the reservoir is absent currently,which fails to support the study of the sweep characteristics of thick reservoirs.Therefore,based on the conformal mapping method,this article transformed the section formation with partially penetrating producer and injector into a formation with a circular boundary and off-center fractured well,a formation with a unit circular boundary and two-branch fractured well,and a section formation with fully penetrating injector and partially penetrating producer,sequentially.The above transformations were repeated to transform the section formation with fully penetrating injector and partially penetrating producer into that with fully penetrating injector and producer.In consequence,the original two-dimensional flow process was transformed into a one-dimensional one,achieving analytical calculations of pressure and streamline distribution in thick reservoirs under different injection-production modes.The comparison with refined numerical simulation methods shows that the proposed method has high computational accuracy for different well spacing-thickness ratios.The influence of injection-production modes on longitudinal sweep characteristics of thick reservoirs was researched using the method presented in this article.The results show that for the bottom-injection-high-production mode,the top section of the injector acts as the main injection layer,and the top 1/3 of the injec‐tor controls more than 1/2 of the formation,resulting in more than 2/3 of the producer being affected.The main impact of water in‐jection on the formation lies in the stage before the water breakthrough.The water breakthrough of bottom-injection-high-production mode is the latest and has the highest sweep efficiency,followed by bottom-injection-medium-produc
作者
童凯军
李长勇
姜俊帅
姜汉桥
李俊键
TONG Kaijun;LI Changyong;JIANG Junshuai;JIANG Hanqiao;LI Junjian(CNOOC International Limited,Beijing City,100008,China;College of Petroleum Engineering,China University of Petroleum(Beijing),Beijing City,102249,China)
出处
《油气地质与采收率》
CAS
CSCD
北大核心
2024年第2期148-154,共7页
Petroleum Geology and Recovery Efficiency
基金
国家自然科学基金项目“水平井控水完井多重耦合精细数值模拟与优化设计方法”(52374055)
中海油“十四五”重大科技项目“米桑油田厚层碳酸盐岩油藏储层表征及加密调整技术研究”(YXKY-GJ-02-202)。
关键词
厚油层
部分打开井
注采模式
保角变换
纵向波及
thick reservoirs
partially penetrating well
production-injection mode
conformal mapping
longitudinal sweep
