焦石坝地区页岩孔隙连通性及有效性评价  

Evaluation of Shale Pore Connectivity and Effectiveness in the Jiaoshiba Area,Sichuan Basin

作　　者：苟启洋 徐尚 郝芳[2] 舒志国[3] GOU QiYang;XU Shang;HAO Fang;SHU ZhiGuo(Key Laboratory of Tectonics and Petroleum Resources Ministry of Education,China University of Geosciences(Wuhan),Wuhan 430074,China;School of Geosciences,China University of Petroleum(Huadong),Qingdao,Shandong 266580,China;Research Institute of Exploration and Development,Jianghan Oilfield Company,SINOPEC,Wuhan 430070,China)

机构地区：[1]中国地质大学(武汉)构造与油气资源教育部重点实验室,武汉430074 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [3]中国石化江汉油田分公司勘探开发研究院,武汉430070

出　　处：《沉积学报》2022年第5期1419-1426,共8页Acta Sedimentologica Sinica

基　　金：国家自然科学基金(41690134,41821002);山东省重点研发计划项目(2020ZLYS08);中国石油大学(华东)自主创新研究计划项目(21CX06001A)。

摘　　要：页岩孔隙连通性直接影响油气分子在储层内的运移,从而控制页岩气产出的难易程度,是评价页岩气勘探开发潜力的重要参数之一。以焦石坝地区两口关键井(JYA井和JYB井)五峰组—龙马溪组主力层段页岩为例,开展柱塞样的氦气孔隙度与饱和盐水后的核磁共振孔隙度实验,确定页岩储层孔隙连通性特征,探讨孔隙连通性对页岩气开发的影响。研究结果显示:1)氦气膨胀法主要识别页岩储层中的连通孔隙,而核磁共振法可有效反映样品整体的孔隙空间,两者的比值可量化表征页岩孔隙连通性;2)JYA井氦气孔隙度和核磁孔隙度差异较小,具有强烈的正相关关系,页岩样品整体以连通孔隙为主,连通孔隙占比为69.13%~94.94%,平均为85.12%;3)JYB井页岩孔隙连通性相对较差,连通孔隙占比为36.15%~81.71%,均值为58.19%,仅依靠连通孔隙无法充分反映页岩样品的真实孔隙度,导致氦气孔隙度和核磁孔隙度无明显线性关系。纳米CT三维成像技术模拟的孔隙连通性特征及研究样品的脉冲渗透率差异证实了研究结果的有效性。Shale pore connectivity directly affects the migration of oil and gas in a reservoir,thus influencing the level of difficulty in shale gas production.It is an important consideration in the evaluation of exploration and development potential of shale gas.Samples from two key wells(JYA and JYB)in the Jiaoshiba area of the Sichuan Basin were tested by helium porosity of plunger samples and nuclear magnetic resonance(NMR)saturated brine porosity to determine the pore connectivity of shale in the reservoir;the influence of pore connectivity on shale gas development is discussed.The results show that the helium expansion method mainly identifies the connected pores in the shale,while the NMR test reflects the overall pore space of the sample.Thus,the ratio of helium porosity to NMR porosity quantitatively characterizes pore connectivity.Only a small difference was found between helium porosity and NMR porosity in well JYA,and they both have a strong positive correlation,suggesting that the pores are mainly connected(69.13%-94.94%,average 85.12%).Conversely,the pore connectivity of shale samples from well JYB was relatively poor(about 36.15%-81.71%,average 58.19%).Therefore,the proportion of connected pores does not fully reflect the true porosity of these samples,and no obvious linear relationship was evident in either the helium porosity or the NMR porosity.These findings were confirmed by nano-computed tomography(nano-CT)and pulse permeability difference tests.

关 键 词：页岩 孔隙度 孔隙连通性 焦石坝地区 四川盆地 

分 类 号：P618.13[天文地球—矿床学]