水锁损害会对油气井产能造成极大的影响,建立一种对水锁损害进行快速预测的方法十分必要。针对低渗砂岩储层发生水锁损害的特点,选取一定数量的低渗砂岩岩心,较系统地评价了在不同的气测渗透率、孔隙度、初始水饱和度以及油水界面张力...水锁损害会对油气井产能造成极大的影响,建立一种对水锁损害进行快速预测的方法十分必要。针对低渗砂岩储层发生水锁损害的特点,选取一定数量的低渗砂岩岩心,较系统地评价了在不同的气测渗透率、孔隙度、初始水饱和度以及油水界面张力条件下的水锁损害程度,采用灰关联分析法对低渗砂岩储层的水锁损害进行了评价和预测研究,并编制了相应的计算程序。灰关联分析实际上就是分析参考序列与比较序列间曲线几何形状的接近程度,一般情况,几何形状越接近,关联度就越大,变化趋势就越接近。灰关联分析步骤为,确定比较序列(子序列)和参考序列(母序列);数据规一化处理;求关联系数;求关联度;关联度按大小排序。结果表明,利用该方法评价和预测低渗砂岩储层的水锁损害是可行的,对影响水锁损害的气测渗透率、孔隙度、初始水饱和度和油水界面张力的4种因素权值分配是合理的。经验证,预测结果有较高的符合率。该方法中的数值计算程序均使用Fortran 4.0在FORTRAN POWER STATION环境下编制而成,在实际应用中能较方便地利用该方法预测低渗砂岩储层的水锁损害程度。展开更多
致密砂岩气已成为非常规天然气勘探开发的重点领域,但由于自身的特性,在钻完井、生产、增产等作业过程中极易造成水锁损害,目前致密砂岩水锁评价方法主要关注水相侵入前后岩心尺度的渗透率变化,未从微观尺度上刻画其水相侵入过程.在深...致密砂岩气已成为非常规天然气勘探开发的重点领域,但由于自身的特性,在钻完井、生产、增产等作业过程中极易造成水锁损害,目前致密砂岩水锁评价方法主要关注水相侵入前后岩心尺度的渗透率变化,未从微观尺度上刻画其水相侵入过程.在深入认识水锁机理的基础上,利用克深J井区巴什基奇克组致密低渗天然岩心,基于毛管自吸实验和水相返排实验,采用核磁共振成像和T2谱技术对水相侵入过程进行了可视化、定量化研究,探讨了水锁过程的微观机理及控制因素.获得了以下认识:(1)离心法建立的初始含水饱和度主要占据相对较小的小孔喉;而T2>100 ms这部分孔喉,代表岩心中相对大的孔喉,自吸水速度快,易于饱和,当含水饱和度Sw=45%~60%时,这部分孔喉吸水就基本达到饱和;(2)核磁共振成像表明,致密岩心(渗透率≤0.02 m D)水相侵入过程中自吸速率较慢,水相饱和度在岩心中呈均匀增加;低渗岩心(渗透率>0.1 m D)水相侵入呈段塞式均匀推进,且自吸速率相对较快;裂缝-基质双重介质岩心水相优先沿裂缝推进,然后基质沿缝面自吸,微裂缝自吸速率最快.(3)物性、微裂缝、初始含水饱和度、侵入流体矿化度、黏土矿物类型及含量和生产压差是影响水相侵入及水相滞留的重要因素.深入认识了致密砂岩水锁机理,完善了水锁效应的控制因素研究,对有效勘探开发致密低渗气藏具有指导意义.展开更多
A pore network model was used in this paper to investigate the factors, in particular, throat radius, wettability and initial water saturation, causing water block in low permeability reservoirs. A new term - ＇relati...A pore network model was used in this paper to investigate the factors, in particular, throat radius, wettability and initial water saturation, causing water block in low permeability reservoirs. A new term - ＇relative permeability number＇ （RPN） was firstly defined, and then used to describe the degree of water block. Imbibition process simulations show that the RPN drops in accordance with the extension of the averaged pore throat radius from 0.05 to 1.5 μm, and yet once beyond that point of 1.5 μm, the RPN reaches a higher value, indicating the existence of a critical pore throat radius where water block is the maximum. When the wettability of the samples changes from water-wet to weakly water-wet, weakly gas-wet, or gas（oil）-wet, the gas RPN increases consistently, but this consistency is disturbed by the RPN dropping for weakly water-wet samples for water saturations less than 0.4, which means weakly waterwet media are more easily water blocked than water-wet systems. In the situation where the initial water saturation exceeds 0.05, water block escalates along with an increase in initial water saturation.展开更多
文摘水锁损害会对油气井产能造成极大的影响,建立一种对水锁损害进行快速预测的方法十分必要。针对低渗砂岩储层发生水锁损害的特点,选取一定数量的低渗砂岩岩心,较系统地评价了在不同的气测渗透率、孔隙度、初始水饱和度以及油水界面张力条件下的水锁损害程度,采用灰关联分析法对低渗砂岩储层的水锁损害进行了评价和预测研究,并编制了相应的计算程序。灰关联分析实际上就是分析参考序列与比较序列间曲线几何形状的接近程度,一般情况,几何形状越接近,关联度就越大,变化趋势就越接近。灰关联分析步骤为,确定比较序列(子序列)和参考序列(母序列);数据规一化处理;求关联系数;求关联度;关联度按大小排序。结果表明,利用该方法评价和预测低渗砂岩储层的水锁损害是可行的,对影响水锁损害的气测渗透率、孔隙度、初始水饱和度和油水界面张力的4种因素权值分配是合理的。经验证,预测结果有较高的符合率。该方法中的数值计算程序均使用Fortran 4.0在FORTRAN POWER STATION环境下编制而成,在实际应用中能较方便地利用该方法预测低渗砂岩储层的水锁损害程度。
文摘致密砂岩气已成为非常规天然气勘探开发的重点领域,但由于自身的特性,在钻完井、生产、增产等作业过程中极易造成水锁损害,目前致密砂岩水锁评价方法主要关注水相侵入前后岩心尺度的渗透率变化,未从微观尺度上刻画其水相侵入过程.在深入认识水锁机理的基础上,利用克深J井区巴什基奇克组致密低渗天然岩心,基于毛管自吸实验和水相返排实验,采用核磁共振成像和T2谱技术对水相侵入过程进行了可视化、定量化研究,探讨了水锁过程的微观机理及控制因素.获得了以下认识:(1)离心法建立的初始含水饱和度主要占据相对较小的小孔喉;而T2>100 ms这部分孔喉,代表岩心中相对大的孔喉,自吸水速度快,易于饱和,当含水饱和度Sw=45%~60%时,这部分孔喉吸水就基本达到饱和;(2)核磁共振成像表明,致密岩心(渗透率≤0.02 m D)水相侵入过程中自吸速率较慢,水相饱和度在岩心中呈均匀增加;低渗岩心(渗透率>0.1 m D)水相侵入呈段塞式均匀推进,且自吸速率相对较快;裂缝-基质双重介质岩心水相优先沿裂缝推进,然后基质沿缝面自吸,微裂缝自吸速率最快.(3)物性、微裂缝、初始含水饱和度、侵入流体矿化度、黏土矿物类型及含量和生产压差是影响水相侵入及水相滞留的重要因素.深入认识了致密砂岩水锁机理,完善了水锁效应的控制因素研究,对有效勘探开发致密低渗气藏具有指导意义.
基金support from the National Key Technology R&D Program in the 11th Five-Year Plan Period (Grant No: 2008ZX05054)the Non-main Petroleum Subject Cultivating Fund of China University of Petroleum.
文摘A pore network model was used in this paper to investigate the factors, in particular, throat radius, wettability and initial water saturation, causing water block in low permeability reservoirs. A new term - ＇relative permeability number＇ （RPN） was firstly defined, and then used to describe the degree of water block. Imbibition process simulations show that the RPN drops in accordance with the extension of the averaged pore throat radius from 0.05 to 1.5 μm, and yet once beyond that point of 1.5 μm, the RPN reaches a higher value, indicating the existence of a critical pore throat radius where water block is the maximum. When the wettability of the samples changes from water-wet to weakly water-wet, weakly gas-wet, or gas（oil）-wet, the gas RPN increases consistently, but this consistency is disturbed by the RPN dropping for weakly water-wet samples for water saturations less than 0.4, which means weakly waterwet media are more easily water blocked than water-wet systems. In the situation where the initial water saturation exceeds 0.05, water block escalates along with an increase in initial water saturation.
