基于双峰高斯函数的海上低渗储层孔隙结构定量表征——以琼东南盆地 BD21 气田陵水组三段为例

Quantitative characterization of pore structure in offshore low-permeability reservoirs based on double-peak Gaussian function: a case study of the third member of the Lingshui Formation in the BD21 Gas Field, Qiongdongnan Basin

摘要

海上低渗气藏占比增加，孔隙结构的差异影响气井产能，制约海上低渗气藏规模开发。根据高压压汞和核磁共振实验，采用测井曲线与储层分类参数、双峰高斯函数拟合曲线等方法，利用球状孔隙模型将核磁共振 T₂ 谱转化为伪毛细管压力曲线定量表征孔径大小及分布，分析核磁共振 T₂ 谱反映的大孔孔隙度、大中孔孔隙度与物性、压汞参数之间关系，分析反映储层渗流能力的孔隙结构评价参数，建立孔隙结构和物性参数预测模型。结果表明：陵水组三段低渗储层孔隙结构分布呈双峰型和单峰型，其中小孔曲线与大孔曲线存在重叠区域，双峰型曲线的重叠区域较小，单峰型曲线的重叠区域较大，孔隙可按双峰高斯函数拟合的小孔曲线、大孔曲线和重叠区域的分布范围划分为大孔、中孔和小孔；大中孔孔隙度、大孔孔隙度可有效评价储层物性和孔隙结构，储层大中孔越发育，物性越好，可动流体饱和度相对较高。以大孔和大中孔综合评价参数为主要指标的低渗储层分类标准，将研究区低渗储层划分为三种类型，其中 I 类、II 类储层大中孔较为发育，储层物性较好，大孔、大中孔综合评价参数值分别大于 7 、 10 ，可动流体饱和度相对较高，普遍在 65.75% 以上；III类储层物性相对较差，大孔和大中孔综合评价参数值较小，孔隙结构复杂，可动流体饱和度相对较低。该结果为海上低渗气田经济有效开发提供指导。

Abstract

The proportion of offshore low-permeability gas reservoirs has increased, and the differences in pore structure have affected well productivity, limiting the development of offshore low-permeability gas reservoirs on a larger scale. To characterize the complex pore-throat structure of low-permeability reservoirs, high-pressure mercury intrusion and nuclear magnetic resonance (NMR) experiments were conducted on low-permeability core samples. The double-peak Gaussian function fitting curve method was used to convert the NMR T₂ spectrum into pseudo-capillary pressure curves to quantitatively characterize pore size and distribution. Furthermore, by analyzing the correlation between the NMR T₂ spectrum and parameters such as large pore volume and medium-large pore porosity, a new parameter that better reflects reservoir flow capacity was constructed for pore-throat evaluation. Lastly, a prediction model for pore-throat and petrophysical parameters was established using multivariate regression based on the response relationship between logging curves and reservoir classification parameters. The results show that the pore-throat distribution of the third section of the Lingshui Formation low-permeability reservoir exhibits bimodal and unimodal patterns, with overlapping regions between small and large pore curves in both types. The overlapping region is smaller in the bimodal pattern and larger in the unimodal pattern. The pore system can be divided into large pores, medium pores, and small pores based on the distribution ranges of the fitted curves for small and large pores and the overlapping region. The medi-um-large pore porosity and large pore porosity effectively evaluate reservoir petrophysical properties and pore structure. The better the large-medium pore system developed, the better the petrophysical properties are, and the higher the movable fluid saturation is. A classification standard for low-permeability reservoirs was established based on comprehensive evaluation parameters primarily focusing on large pores and medium-large pores. The reservoirs were divided into three types. Type I and type II reservoirs have better development of large-medium pores and good petrophysical properties, comprehensive evaluation parameter values are greater than 7 and 10 respectively, and relatively high movable fluid saturation is generally above 65.75%. Type III reservoirs have relatively poor petrophysical properties, smaller values for comprehensive evaluation parameters of large pores and medium-large pores, complex pore-throat structure, and relatively low movable fluid saturation. These results can provide guidance for the economic and effective development of low-permeability gas fields.

关键词

低渗储层 / 孔隙结构表征 / 双峰高斯函数 / 孔隙结构评价参数 / 预测模型 / 陵水组三段 / 琼东南盆地

Key words

low-permeability reservoirs / pore structure characterization / double-peak Gaussian function / pore-throat evaluation parameters / prediction model / the third member of Lingshui Formation / Qiongdongnan Basin

参考文献

[1] 房涛, 张立宽, 刘乃贵, 等. 核磁共振技术定量表征致密砂岩气储层孔隙结构:以临清坳陷东部石炭系一二叠系致密砂岩储层为例[J]. 石油学报, 2017, 38(8):902-915.

[2] FANG Tao, ZHANG Likuan, LIU Naigui, et al. Quantitative characterization of pore structure of tight gas sandstone reservoirs by NMR T₂ spectrum technology:a case study of Carboniferous-Permian tight sandstone reservoir in Linqing Depression[J]. Acta Petrolei Sinica, 2017, 38(8):902-915.

[3] 贾承造, 郑民, 张永峰. 中国非常规油气资源与勘探开发前景[J]. 石油勘探与开发, 2012, 39(2):129-136.

[4] JIA Chengzao, ZHENG Min, ZHANG Yongfeng. Unconventional hydrocarbon resources in China and the prospect of exploration and development[J]. Petroleum Exploration and Development, 2012, 39(2):129-136.

[5] 赵华伟, 宁正福, 段太忠, 等. 基于微米 CT 扫描成像实验及格子 Boltzmann 模拟方法的致密砂岩孔隙结构表征[J]. 东北石油大学学报, 2019, 43(5):1-10.

[6] ZHAO Huawei, NING Zhengfu, DUAN Taizhong, et al. Pore structure characterization of tight sand stones by X-ray computed tomography experiment combined with lattice Boltzmann method[J]. Journal of Northeast Petroleum University, 2019, 43(5):1-10.

[7] 张浩. 阿尔凹陷腾一段储层微观孔隙结构与渗流特征研究[D]. 西安: 西北大学,2017:31-57.

[8] ZHANG Hao. Research of micro-pore structure and seepage characteristics of Et₁ in A'er Sag of Erlian Basin[D]. Xían: Northwest U- niversity,2017:31-57.

[9] 孟婧, 张莉莹, 李芮, 等. 致密砂岩储层微观孔隙结构特征及其分类评价[J]. 特种油气藏, 2023, 30(4):71-78.

[10] MENG Jing, ZHANG Liying, LI Rui, et al. Microscopic pore structure characteristics of tight sandstone reservoirs and its classification evaluation[J]. Special Oil & Gas Reservoirs, 2023, 30(4):71-78.

[11] 刘丽萍, 白海涛, 王西强, 等. 鄂尔多斯盆地白豹油田长 8₁ 储层水驱油特征及驱油效率影响因素[J]. 东北石油大学学报, 2022, 46(6): 63-74.

[12] LIU Liping, BAI Haitao, WANG Xiqiang, et al. Water flooding characteristics and influencing factors of oil displacement efficiency of Chang 81 Reservoir in Baibao Oilfield,Ordos Basin[J]. Journal of Northeast Petroleum University, 2022, 46(6):63-74.

[13] 卫弘媛, 谢然红, 王跃祥, 等. 四川盆地沙溪庙组致密砂岩储层孔隙结构与分类[J]. 东北石油大学学报, 2023, 47(3):34-43.

[14] WEI Hongyuan, XIE Ranhong, WANG Yuexiang, et al. Pore structure characterization and reservoir classification in tight sandstone reservoirs of the Shaximiao Formation in Sichuan Basin[J]. Journal of Northeast Petroleum University, 2023, 47(3):34-43.

[15] DESBOIS G, URAI J L, KUKLA P A, et al. High-resolution 3D fabric and porosity model in a tight gas sandstone reservoir:a new approach to investigate microstructures from mm to nm scale combing argon beam cross sectioning and SEM imaging[J]. Journal of Petroleum Science and Engineering, 2011,78:243-257.

[16] 钟红利, 张凤奇, 赵振宇, 等. 致密砂岩储层微观孔喉分布特征及对可动流体的控制作用[J]. 石油实验地质, 2021, 43(1):77-85.

[17] ZHONG Hongli, ZHANG Fengqi, ZHAO Zhenyu, et al. Micro-scale pore-throat distributions in tight sandstone reservoirs and its constrain to movable fluid[J]. Petroleum Geology & Experiment, 2021, 43(1):77-85.

[18] 蒋裕强, 陈林, 蒋婵, 等. 致密储层孔隙结构表征技术及发展趋势[J]. 地质科技情报, 2014, 33(3):63-70.

[19] JIANG Yuqiang, CHEN Lin, JIANG Chan, et al. Characterization techniques and trends of the pore structure of tight reservoirs[J]. Geological Science and Technology Information, 2014, 33(3):63-70.

[20] 朱如凯, 白斌, 崔景伟, 等. 非常规油气致密储集层微观结构研究进展[J]. 古地理学报, 2013, 15(5):615-623.

[21] ZHU Rukai, BAI Bin, CUI Jingwei, et al. Research advances of microstructure in unconventional tight oil and gas reservoirs[J]. Journal of Palaeogeography, 2013, 15(5):615-623.

[22] 刘刚, 吴浩, 张春林, 等. 基于压汞和核磁共振对致密油储层渗透率的评价:以鄂尔多斯盆地陇东地区延长组长 7 油层组为例[J]. 高校地质学报, 2017, 23(3):511-520.

[23] LIU Gang, WU Hao, ZHANG Chunlin, et al. Permeability evaluation of tight oil sandstone reservoirs based on MICP and NMR data:a case study from Chang 7 Reservoir of the Yanchang Formation in the Longdong Area,Ordos Basin[J]. Geological Journal of China Universities, 2017, 23(3):511-520.

[24] 公言杰, 柳少波, 赵孟军, 等. 核磁共振与高压压汞实验联合表征致密油储层微观孔喉分布特征[J]. 石油实验地质, 2016, 38(3): 389-394.

[25] GONG Yanjie, LIU Shaobo, ZHAO Mengjun, et al. Characterization of micro pore throat radius distribution in tight oil reservoirs by NMR and high pressure mercury injection[J]. Petroleum Geology & Experiment, 2016, 38(3):389-394.

[26] YUAN H H, SWANSON B F. Resolving pore-space characteristics by rate-controlled porosimetry[R]. SPE 14892,1989:23-28.

[27] 肖佃师, 卢双舫, 陆正元, 等. 联合核磁共振和恒速压汞方法测定致密砂岩孔喉结构[J]. 石油勘探与开发, 2016, 43(6):961-970.

[28] XIAO Dianshi, LU Shuangfang, LU Zhengyuan, et al. Combining nuclear magnetic resonance and rate-controlled porosimetry to probe the pore-throat structure of tight sandstones[J]. Petroleum Exploration and Development, 2016, 43(6):961-970.

[29] GAULIER C. Studying vugular rocks by-constant-rate mercury injection[R]. SPE 3612,1971:35-39.

[30] 张冲, 杨朝强, 汪新光, 等. 北部湾盆地复杂低渗储层品质分级表征[J]. 断块油气田, 2022, 29(4):483-488.

[31] ZHANG Chong, YANG Zhaoqiang, WANG Xinguang, et al. Classification and characterization of complex low-permeability reservoir quality in Beibuwan Basin[J]. Fault-Block Oil and Gas Field, 2022, 29(4):483-488.

[32] 汪新光, 张冲, 张辉, 等. 涠西南凹陷低渗储层可动流体百分数定量表征方法[J]. 中国海上油气, 2020, 32(6):90-98.

[33] WANG Xinguang, ZHANG Chong, ZHANG Hui, et al. Quantitative characterization method of movable fluid percentage in low permeability reservoirs of Weixinan Sag[J]. China Offshore Oil and Gas, 2020, 32(6):90-98.

[34] 王学武, 杨正明, 李海波, 等. 核磁共振研究低渗透储层孔隙结构方法[J]. 西南石油大学学报(自然科学版), 2010, 32(2):69-72.

[35] WANG Xuewu, YANG Zhengming, LI Haibo, et al. Experimental study on pore structure of low permeability core with NMR spectra[J]. Journal of Southwest Petroleum University(Science & Technology Edition), 2010, 32(2):69-72.

[36] 高辉, 孙卫, 田育红, 等. 核磁共振技术在特低渗砂岩微观孔隙结构评价中的应用[J]. 地球物理学进展, 2011, 26(1):294-299.

[37] GAO Hui, SUN Wei, TIAN Yuhong, et al. Application of NMR technique in evaluation of micro pore structure in extra-low permeability sandstone[J]. Progress in Geophysics, 2011, 26(1):294-299.

[38] 张超谟, 陈振标, 张占松, 等. 基于核磁共振 T₂ 谱分布的储层岩石孔隙分形结构研究[J]. 石油天然气学报, 2007, 29(4):80-86.

[39] ZHANG Chaomo, CHEN Zhenbiao, ZHANG Zhansong, et al. Fractal characteristics of reservoir rock pore structure based on NMR T₂ distribution[J]. Journal of Oil and Gas Technology, 2007, 29(4):80-86.

[40] 郭兰, 丁超, 门艳萍, 等. 基于核磁共振(NMR)技术进行致密储层参数研究:以鄂尔多斯盆地南部富县油田延长组长 8 致密储层为例[J]. 非常规油气, 2017, 4(3):29-35.

[41] GUO Lan, DING Chao, MEN Yanping, et al. Research on tight reservoir parameters based on nuclear magnetic resonance(NMR) technology:a case study of Chang 8 tight reservoir in Yanchang Formation,Fuxian Oilfield,Southern Ordos Basin[J]. Unconventional Oil and Gas, 2017, 4(3):29-35.

[42] 崔雁虎, 朱国涛, 朱杰, 等. 玛 2 井区百口泉组砂砾岩储层可动流体赋存特征及主控因素[J]. 东北石油大学学报, 2022, 46(6):14-25.

[43] CUI Yanhu, ZHU Guotao, ZHU Jie, et al. Occurrence characteristics and control factors of movable fluids in Baikouquan Formation glutenite reservoirs in Ma 2 Block[J]. Journal of Northeast Petroleum University, 2022, 46(6):14-25.

[44] 付炜, 胡望水, 王晓晨, 等. 致密砂岩储层特征及质量影响因素:以鄂尔多斯盆地西北部二叠系下石盒子组为例[J]. 东北石油大学学报, 2023, 47(5):36-48.

[45] FU Wei, HU Wangshui, WANG Xiaochen, et al. Characteristics of tight sandstone reservoir and influencing factors of reservoir quality:a case study in Lower Shihezi Formation of Permian,Northwest Ordos Basin[J]. Journal of Northeast Petroleum University, 2023, 47(5):36-48.

[46] 张玥, 汤济广, 胡美玲, 等. 松辽盆地南部大安地区青山口组一段页岩储层微观孔隙结构[J]. 特种油气藏, 2023, 30(5):58-66.

[47] ZHANG Yue, TANG Jiguang, HU Meiling, et al. Microscopic pores structure of shale reservoir in member 1 of Qingshankou Formation,Daan Area of Southern Songliao Basin[J]. Special Oil & Gas Reservoirs, 2023, 30(5):58-66.

[48] 宁凡, 赵欣, 邹妞妞, 等. 柴北缘侏罗系大煤沟组砂岩储层孔喉分布特征[J]. 非常规油气, 2022, 9(3):42-51.

[49] NING Fan, ZHAO Xin, ZOU Niuniu, et al. Distribution characteristics of pore throat of sandstone reservoir of Jurassic Dameigou Formation in Northern Qaidam Basin[J]. Unconventional Oil & Gas, 2022, 9(3):42-51.

[50] 杜焕福, 侯瑞卿, 孙鑫, 等. 基于核磁共振的页岩孔隙结构特征研究[J]. 非常规油气, 2023, 10(5):38-47.

[51] DU Huanfu, HOU Ruiqing, SUN Xin, et al. Study on pore structure characteristics of shale based on NMR[J]. Unconventional Oil & Gas, 2023, 10(5):38-47.

[52] 钟红利, 吴雨风, 张风奇, 等. 陕北斜坡东南部致密砂岩孔喉分布及其对含油性的影响[J]. 断块油气田, 2021, 28(1):21-27.

[53] ZHONG Hongli, WU Yufeng, ZHANG Fengqi, et al. Pore throat distribution of tight sandstone in the southeast of the Northern Shaanxi Slope and its influence on oil-bearing property[J]. Fault-Block Oil & Gas Field, 2021, 28(1):21-27.

[54] 屈凯旋, 李国良, 于春勇, 等. 基于核磁共振 T₂ 谱的致密砂岩孔喉分布评价方法[J]. 录井工程, 2023, 34(2):1-8.

[55] QU Kaixuan, LI Guoliang, YU Chunyong, et al. Evaluation method of pore throat distribution in tight sandstones based on NMR T₂ spectrum[J]. Mud Logging Engineering, 2023, 34(2):1-8.

[56] 尤丽, 权永彬, 席雷, 等. 琼东南盆地深水区宝岛 2X-1 气田天然气来源及输导体系[J]. 石油与天然气地质, 2023, 44(5):1270-1278.

[57] YOU Li, QUAN Yongbin, TUO Lei, et al. Natural gas sources and migration pathways of the Baodao 2X-1 Gas Field in the deepwater area of the Qiongdongnan Basin[J]. Oil & Gas Geology, 2023, 44(5):1270-1278.

[58] 徐长贵, 邓勇, 吴克强, 等. 南海北部强活动型被动陆缘盆地宝岛 2X-1 大气田的发现及地质意义[J]. 石油学报, 2023, 44(5):713-729.

[59] XU Changgui, DENG Yong, WU Keqiang, et al. Discovery and geological significance of the large gas field Baodao 2X-1 in a passive epicontinental basin with strong activity in the Northern South China Sea[J]. Acta Petrolei Sinica, 2023, 44(5):713-729.

[60] 徐长贵, 尤丽. 琼东南盆地松南-宝岛凹陷北坡转换带特征及其对大中型气田的控制[J]. 石油勘探与开发, 2022, 49(6):1061-1072.

[61] XU Changgui, YOU Li. North slope transition zone of Songnan-Baodao Sag in Qiongdongnan Basin and its control on medium and large gas fields,South China Sea[J]. Petroleum Exploration and Development, 2022, 49(6):1061-1072.

[62] 邓勇, 裴健翔, 胡林, 等. 南海西部海域宝岛 2X-1 气田的发现与成藏模式[J]. 中国海上油气, 2022, 34(5):13-22.

[63] DENG Yong, PEI Jianxiang, HU Lin, et al. Discovery and hydrocarbon accumulation models of Baodao 2X-1 Gas Field in the Western South China Sea[J]. China Offshore Oil and Gas, 2022, 34(5):13-22.

[64] 宁传祥, 姜振学, 高之业, 等. 用核磁共振和高压压汞定量评价储层孔隙连通性:以沾化凹陷沙三下亚段为例[J]. 中国矿业大学学报, 2017, 46(3):578-585.

[65] NING Chuanxiang, JIANG Zhenxue, GAO Zhiye, et al. Quantitative evaluation of pore connectivity with nuclear magnetic resonance and high pressure mercury injection:a case study of the lower section of Es₃ in Zhanhua Sag[J]. Journal of China University of Mining & Technology, 2017, 46(3):578-585.

[66] ZHANG F, JIANG Z, SUN W, et al. A multiscale comprehensive study on pore structure of tight sandstone reservoir realized by nuclear magnetic resonance,high pressure mercury injection and constant-rate mercury injection penetration test[J]. Marine and Petroleum Geology, 2019,109:208-222.

[67] 谢增业, 杨春龙, 李剑, 等. 致密砂岩气藏充注模拟实验及气藏特征:以川中地区上三叠统须家河组砂岩气藏为例[J]. 天然气工业, 2020, 40(11):31-40.

[68] XIE Zengye, YANG Chunlong, LI Jian, et al. Charging simulation experiment and characteristics of tight sandstone gas reservoirs: a case study of the Upper Triassic Xujiahe Formation sandstone gas reservoir in the Central Sichuan Basin[J]. Natural Gas Industry, 2020, 40(11):31-40.

[69] 何晓群. 多元统计分析[M]. 第5版. 北京: 中国人民大学出版社,2019:112-136.

[70] HE Xiaoqun. Multivariate statistical analysis[M]. 5th ed. Beijing: Renmin University of China Press,2019:112-136.

基金资助

国家科技重大专项(2016ZX05026-002)

中海石油（中国）有限公司重大科技专项(CNOOC-KJ135ZDXM38ZJ)