Effects of magnetic field intensity and gradient on measurement results of core nuclear magnetic resonance T2 spectrum
-
摘要: 核磁共振测井仪器一般在共振频率为2 MHz的均匀场或共振频率小于1 MHz的梯度场中测量储层流体的核磁信号，而实验室核磁共振岩心分析仪的共振频率除了常用的2 MHz外，对于页岩等致密储层常会用到12 MHz或21 MHz的设备进行实验测量。为确定磁场强度和磁场梯度对核磁共振测量结果的影响程度，系统研究了饱和水状态下的砂砾岩、页岩核磁共振岩心实验对磁场强度和磁场梯度的敏感性，分析了不同岩样的T2谱形态、位置、核磁孔隙度、T2几何均值与磁场强度、磁场梯度的关系。实验结果显示，均匀场下，砂砾岩样品对磁场强度的变化非常敏感，而页岩样品对磁场强度变化的敏感性相对较弱；外部梯度场的存在会使砂砾岩和页岩的短弛豫信息缺失，导致核磁信号无法被完全测量。研究表明，利用核磁共振岩心实验刻度核磁共振测井解释参数时，若实验室核磁共振岩心分析仪与核磁共振测井仪的磁场强度或磁场梯度存在较大差异，需对实验测量结果进行校正。Abstract: Nuclear magnetic resonance(NMR) logging instruments generally measure the NMR signal of reservoir fluid in a uniform field with a resonance frequency of 2 MHz or a gradient field with a resonance frequency of less than 1 MHz. For laboratory NMR core analyzers, in addition to the commonly used 2 MHz, the resonance frequency of 12 MHz or 21 MHz is often used for experimental measurement of tight reservoirs such as shale. In order to determine the effects of magnetic field intensity and gradient on the NMR measurement results, the sensitivity of the magnetic field intensity and gradient of the core experiments of glutenite and shale cores under water-saturatedstate was systematically studied, and the relationship between the T2 spectrum shape, position, nuclear magnetic porosity, T2 geometric mean and the magnetic field intensity and gradient of different rock samples was analyzed. The experimental results show that under the uniform field, glutenite samples are very sensitive to the change of magnetic field intensity, while shale samples are less sensitive. The existence of external gradient field will make the short relaxation information of glutenite and shale missing, resulting in that the NMR signal cannot be measured completely. When the NMR core experiment is used to calibrate the interpretation parameters of NMR logging, the experimental measurement results must be corrected if there is a large difference in the magnetic field intensity or gradient between the laboratory NMR core analyzer and the NMR logging instrument.
-
Key words:
- nuclear magnetic resonance /
- magnetic field intensity /
- magnetic field gradient /
- T2 spectrum /
- glutenite /
- shale
-
图 3 核磁共振实验中4块饱水样品在不同磁场强度、梯度下的T2谱测量结果
Figure 3. T2 spectrum results of four water-saturated samples in different magnetic field intensities and gradients in NMR experiment
图 4 核磁共振实验样品的气测孔隙度与核磁视孔隙度对比
Figure 4. Comparison of gas porosity and nuclear magnetic apparent porosity of NMR experimental samples
图 5 核磁共振实验样品在不同磁场强度、梯度下的核磁视孔隙度对比
Figure 5. Nuclear magnetic apparent porosity comparison of NMR experimental samples in different magnetic field intensities and gradients
图 6 核磁共振实验样品在不同磁场强度、磁场梯度下的T2几何均值对比
Figure 6. T2 geometric mean comparison of NMR experimental samples in different magnetic field intensities and gradients
表 1 核磁共振实验岩心基础参数
Table 1. Basic parameters of NMR experimental core
岩心编号 岩性 长度/cm 直径/cm 取样深度/m 气测孔隙度/% 1号 砂砾岩 3.108 0 2.474 0 4 067.32 7.96 2号 砂砾岩 3.727 3 2.531 7 4 071.44 9.22 3号 页岩 2.301 3 2.489 0 3 034.20 5.76 4号 页岩 2.417 0 2.489 5 3 578.50 4.63 
下载: 导出CSV
表 2 核磁共振实验采集参数
Table 2. Parameters acquired by NMR experiment
磁场环境 等待时间(TW)/ms 回波间隔(TE)/ms 回波个数(NECH) 扫描次数(SCAN) 1 MHz梯度场 6 000 0.2 1 600 2 048 1 MHz均匀场 6 000 0.2 1 600 256 2 MHz均匀场 6 000 0.2 1 600 256 21 MHz均匀场 6 000 0.2 1 600 32
下载: 导出CSV
表 3 核磁共振实验样品在不同磁场强度、梯度下的T2谱形态
Table 3. T2 spectrum shape of NMR experimental samples in different magnetic field intensities and gradients
样品编号 1 MHz梯度场 1 MHz均匀场 2 MHz均匀场 21 MHz均匀场 1 双峰 双峰 双峰 梯形 2 双峰 三峰 双峰 梯形 3 双峰(左、右峰占比相当) 4 双峰(以左峰为主，右峰占比较小)
下载: 导出CSV
表 4 核磁共振实验砂砾岩样品在不同磁场强度、梯度下的T2谱位置
Table 4. T2 spectrum positions of NMR experimental glutenite samples in different magnetic field intensities and gradients
ms 岩心编号 1 MHz梯度场 1 MHz均匀场 2 MHz均匀场 21 MHz均匀场 半弛豫时间 起始时间 终止时间 半弛豫时间 起始时间 终止时间 半弛豫时间 起始时间 终止时间 半弛豫时间 起始时间 终止时间 1 10.50 0.80 80.31 13.90 0.52 193.07 10.16 0.11 299.36 4.12 0.06 2 154.44 2 29.40 1.93 372.76 33.42 1.00 719.69 24.19 0.06 896.15 5.78 0.05 1 115.88
下载: 导出CSV
表 5 核磁共振实验页岩样品在不同磁场强度、梯度下的T2谱谱峰位置
Table 5. T2 peak positions of NMR experimental shale samples in different magnetic field intensities and gradients
ms 岩心编号 1 MHz梯度场 1 MHz均匀场 2 MHz均匀场 21 MHz均匀场 左峰 右峰 左峰 右峰 左峰 右峰 左峰 右峰 3 1.93 80.3 0.80 100 0.42 100 0.33 26.8 4 1.55 193.1 1.25 155.1 1.0 193.1 0.80 299.4
下载: 导出CSV
-
[1] 王伟, 赵延伟, 毛锐, 等. 页岩油储层核磁有效孔隙度起算时间的确定: 以吉木萨尔凹陷二叠系芦草沟组页岩油储层为例[J]. 石油与天然气地质, 2019, 40(3): 550-557. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT201903011.htmWANG Wei, ZHAO Yanwei, MAO Rui, et al. Determination of the starting time for measurement of NMR effective porosity in shale oil reservoir: a case study of the Permian Lucaogou shale oil reservoir, Jimusaer Sag[J]. Oil & Gas Geology, 2019, 40(3): 550-557. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT201903011.htm [2] 彭石林, 胡以良, 刘崇汉. 岩心核磁共振实验分析与常规物性测量对比[J]. 测井技术, 1998, 22(S1): 6-10. https://www.cnki.com.cn/Article/CJFDTOTAL-CJJS8S1.001.htmPENG Shilin, HU Yiliang, LIU Chonghan. Comparison between core NMR experimental analysis and conventional physical property measurement[J]. Well Logging Technology, 1998, 22(S1): 6-10. https://www.cnki.com.cn/Article/CJFDTOTAL-CJJS8S1.001.htm [3] 邓克俊. 核磁共振测井理论及应用[M]. 东营: 中国石油大学出版社, 2010.DENG Kejun. Nuclear magnetic resonance logging theory and application[M]. Dongying: China University of Petroleum Press, 2010. [4] ANAND V, ALI M R, AL-ADANI N, et al. New generation NMR tool for robust, continuous T1 and T2 measurements[C]//Proceedings of SPWLA 201656th Annual Logging Symposium. Long Beach: SPWLA, 2015. [5] 王俊明, 邵维志, 韩成, 等. MRIL-Prime核磁共振测井仪[J]. 石油仪器, 2002, 16(6): 18-20. doi: 10.3969/j.issn.1004-9134.2002.06.007WANG Junming, SHAO Weizhi, HAN Cheng, et al. MRIL-Prime nuclear magnetic resonant image logging tool[J]. Petroleum Instruments, 2002, 16(6): 18-20. doi: 10.3969/j.issn.1004-9134.2002.06.007 [6] 邰子伟, 刘德叶, 黎明华. 三种核磁共振测井仪器的比较[J]. 核电子学与探测技术, 2006, 26(6): 1049-1051. doi: 10.3969/j.issn.0258-0934.2006.06.095TAI Ziwei, LIU Deye, LI Minghua. The comparison for three type of NMR logging tool[J]. Nuclear Electronics & Detection Technology, 2006, 26(6): 1049-1051. doi: 10.3969/j.issn.0258-0934.2006.06.095 [7] 孙中良, 李志明, 申宝剑, 等. 核磁共振技术在页岩油气储层评价中的应用[J]. 石油实验地质, 2022, 44(5): 930-940. doi: 10.11781/sysydz202205930SUN Zhongliang, LI Zhiming, SHEN Baojian, et al. NMR technology in reservoir evaluation for shale oil and gas[J]. Petroleum Geology & Experiment, 2022, 44(5): 930-940. doi: 10.11781/sysydz202205930 [8] 江昀, 许国庆, 石阳, 等. 致密岩心带压渗吸规律实验研究[J]. 石油实验地质, 2021, 43(1): 144-153. doi: 10.11781/sysydz202101144JIANG Yun, XU Guoqing, SHI Yang, et al. Forced imbibition in tight glutenite cores[J]. Petroleum Geology & Experiment, 2021, 43(1): 144-153. doi: 10.11781/sysydz202101144 [9] 谢然红, 肖立志, 刘天定. 原油的核磁共振弛豫特性[J]. 西南石油大学学报, 2007, 29(5): 21-24. doi: 10.3863/j.issn.1674-5086.2007.05.006XIE Ranhong, XIAO Lizhi, LIU Tianding. NMR relaxation properties of crude oils[J]. Journal of Southwest Petroleum University, 2007, 29(5): 21-24. doi: 10.3863/j.issn.1674-5086.2007.05.006 [10] KAUSIK R, FELLAH K, FENG L, et al. High- and low-field NMR relaxometry and diffusometry of the Bakken petroleum system[J]. Petrophysics, 2017, 58(4): 341-351. http://www.nstl.gov.cn/paper_detail.html?id=ef053bfa5ff1c09e22fe287680dcc029 [11] TROMP R R, PEL L. NMR T1 dispersion of crude oils from 10 kHz to 20 MHz[J]. Journal of Magnetic Resonance, 2021, 325: 106949. doi: 10.1016/j.jmr.2021.106949 [12] KORB J P. Nuclear magnetic relaxation of liquids in porous media[J]. New Journal of Physics, 2011, 13(3): 035016. doi: 10.1088/1367-2630/13/3/035016 [13] CUI Yingzhi, SHIKHOV I, LI Rupeng, et al. A numerical study of field intensity and clay morphology impact on NMR transverse relaxation in glutenites[J]. Journal of Petroleum Science and Engineering, 2021, 202: 108521. http://www.sciencedirect.com/science/article/pii/S0920410521001807 [14] 覃莹瑶, 张宫, 张嘉伟, 等. 磁场强度对T2-T1二维核磁共振实验的影响研究[J]. 地球物理学进展, 2021, 36(5): 2082-2089. https://www.cnki.com.cn/Article/CJFDTOTAL-DQWJ202105030.htmQIN Yingyao, ZHANG Gong, ZHANG Jiawei, et al. Study on the influence of magnetic field intensity on T2-T1 two-dimensional nuclear magnetic resonance experiment[J]. Progress in Geophysics, 2021, 36(5): 2082-2089. https://www.cnki.com.cn/Article/CJFDTOTAL-DQWJ202105030.htm [15] 梁灿, 肖立志, 周灿灿, 等. 岩石润湿性的核磁共振表征方法与初步实验结果[J]. 地球物理学报, 2019, 62(11): 4472-4481. https://www.cnki.com.cn/Article/CJFDTOTAL-DQWX201911039.htmLIANG Can, XIAO Lizhi, ZHOU Cancan, et al. Nuclear magnetic resonance characterizes rock wettability: preliminary experimental results[J]. Chinese Journal of Geophysics, 2019, 62(11): 4472-4481. https://www.cnki.com.cn/Article/CJFDTOTAL-DQWX201911039.htm [16] 余玥, 孙一迪, 高睿, 等. 基于T2截止值确定致密岩心表面弛豫率[J]. 石油实验地质, 2022, 44(2): 342-349. doi: 10.11781/sysydz202202342YU Yue, SUN Yidi, GAO Rui, et al. Determination of surface relaxivity for tight glutenite cores based on T2 cut-off value[J]. Petroleum Geology & Experiment, 2022, 44(2): 342-349. doi: 10.11781/sysydz202202342 [17] MCDONALD P J, KORB J P, MITCHELL J, et al. Surface relaxation and chemical exchange in hydrating cement pastes: a two-dimensional NMR relaxation study[J]. Physical Review E, 2005, 72(1): 011409. http://www.xueshufan.com/publication/2134673969 [18] GODEFROY S, KORB J P, FLEURY M, et al. Surface nuclear magnetic relaxation and dynamics of water and oil in macroporous media[J]. Physical Review E, 2001, 64(2): 021605. http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PLEEE8000064000002021605000001&idtype=cvips&gifs=Yes [19] COATES G, 肖立志, PRAMMER M. 核磁共振测井原理与应用[M]. 孟繁莹, 译. 北京: 石油工业出版社, 2007.COATES G, XIAO Lizhi, PRAMMER M. Principles and applications of NMR logging[M]. MENG Fanying, trans. Beijing: Petroleum Industry Press, 2007. [20] 张宫, 何宗斌, 曹文倩, 等. 回波间隔对核磁共振表观孔隙度的影响及矫正方法[J]. 波谱学杂志, 2020, 37(2): 172-181. https://www.cnki.com.cn/Article/CJFDTOTAL-PPXZ202002005.htmZHANG Gong, HE Zongbin, CAO Wenqian, et al. Effects of echo time on NMR apparent porosity and correction methods[J]. Chinese Journal of Magnetic Resonance, 2020, 37(2): 172-181. https://www.cnki.com.cn/Article/CJFDTOTAL-PPXZ202002005.htm [21] 毛克宇. 火成岩核磁共振数值模拟与影响因素分析[J]. 地球物理学进展, 2015, 30(4): 1755-1762. https://www.cnki.com.cn/Article/CJFDTOTAL-DQWJ201504031.htmMAO Keyu. Analysis on influence factors based on NMR simulation in igneous rocks[J]. Progress in Geophysics, 2015, 30(4): 1755-1762. https://www.cnki.com.cn/Article/CJFDTOTAL-DQWJ201504031.htm [22] 国家能源局. SY/T 6490-2014, 岩样核磁共振参数实验室测量规范[S]. 北京: 石油工业出版社, 2015.National Energy Administration. SY/T 6490-2014, Specification for measurement of rock NMR parameter in laboratory[S]. Beijing: Petroleum Industry Press, 2015. [23] 刘欢, 徐锦绣, 郑炀, 等. 渤海J油田储层核磁共振测井孔隙度影响因素分析及校正[J]. 波谱学杂志, 2020, 37(3): 370-380. https://www.cnki.com.cn/Article/CJFDTOTAL-PPXZ202003011.htmLIU Huan, XU Jinxiu, ZHENG Yang, et al. Factors affecting and correction methods for porosity measured by NMR logging in the J oilfield of Bohai Bay[J]. Chinese Journal of Magnetic Resonance, 2020, 37(3): 370-380. https://www.cnki.com.cn/Article/CJFDTOTAL-PPXZ202003011.htm [24] 张宫, 冯庆付, 武宏亮, 等. 基于核磁T2谱对数均值差异的碳酸盐岩气水识别[J]. 天然气地球科学, 2017, 28(8): 1243-1249. https://www.cnki.com.cn/Article/CJFDTOTAL-TDKX201708012.htmZHANG Gong, FENG Qingfu, WU Hongliang, et al. Gas-water identification of carbonate reservoir based on log mean difference of T2 spectrum[J]. Natural Gas Geoscience, 2017, 28(8): 1243-1249. https://www.cnki.com.cn/Article/CJFDTOTAL-TDKX201708012.htm -
图(6) / 表(5)
计量
- 文章访问数: 478
- HTML全文浏览量: 277
- PDF下载量: 56
- 被引次数: 0
苏公网安备32021102000780号