Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield

Wang Xixi; Meng Yue; Li Yongfeng; Hu Guilin

doi:doi:10.11648/j.sd.20251302.11

Research Article |

| Peer-Reviewed

Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield

Wang Xixi^*, Meng Yue, Li Yongfeng, Hu Guilin

Published in Science Discovery (Volume 13, Issue 2)

Received: 7 March 2025 Accepted: 27 March 2025 Published: 31 March 2025

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Abstract

This study presents a comprehensive investigation of the pore-throat characteristics in the Chang 9 tight sandstone reservoir of Ansai Oilfield, Ordos Basin, utilizing an integrated multiscale characterization approach. By combining image-based pore analysis, high-pressure and rate-controlled mercury intrusion porosimetry, nuclear magnetic resonance (NMR) relaxation spectroscopy, and nano-CT three-dimensional reconstruction, we established a complete pore-throat characterization methodology spanning multiple scales.The experimental results demonstrate that the reservoir exhibits a bimodal pore-throat distribution, with an average two-dimensional pore radius of 21.51 μm. The three-dimensional pore-throat network is characterized by predominant throat sizes of 0.15 μm (ranging 0.006-1 μm) and pore sizes of 120 μm (60-270 μm). NMR analysis reveals that the lower threshold radius for movable fluids ranges from 0.88 to 8.94 μm, showing significant positive correlation with reservoir quality parameters.A well-developed microfracture network with apertures of 0.07-4.80 μm was identified, which substantially enhances the reservoir's flow capacity. The successful integration of multiple characterization techniques enables complete pore-throat structure characterization across all relevant scales in tight sandstone reservoirs.These findings provide both theoretical foundations and practical guidance for sweet spot identification, reservoir evaluation, and hydrocarbon exploration/development in tight sandstone formations. The established methodology offers valuable insights for understanding fluid storage and flow mechanisms in low-permeability reservoirs.

Published in	Science Discovery (Volume 13, Issue 2)
DOI	10.11648/j.sd.20251302.11
Page(s)	16-24
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2025. Published by Science Publishing Group

Keywords

Pore-throat Structure, Mercury Intrusion Capillary Pressure (MICP), Nuclear Magnetic Resonance (NMR), CT Examination, Ansai Oilfield

1．引言

致密砂岩储层作为重要的非常规油气资源，具有分布广泛、资源潜力巨大的特点，已成为全球油气勘探开发的重点领域之一

[1, 2]

。深入研究致密砂岩储层的微观孔喉结构特征，有助于识别优质"甜点"区，为提升油气勘探开发效率提供关键理论支撑

[3, 4]

。由于致密储层以微米-纳米级孔隙为主，需采用系统实验方法进行表征，而现有研究多局限于单一实验方法的对比分析，如铸体薄片、扫描电镜观察孔喉类型，高压压汞、核磁共振定量表征孔隙结构，或利用纳米CT三维刻画孔喉分布

[5]

。由于不同实验手段在表征范围和尺度上各具特点，难以全面揭示储层孔隙结构特征。因此，采用多方法联合表征已成为深入研究储层微观孔喉结构的必然趋势

[6]

。

尽管安塞油田长9储层已受到广泛关注，但将多种实验手段有机结合、系统表征其孔喉特征的研究仍较为匮乏。基于此，本研究在传统铸体薄片显微观察的基础上，整合多种现代实验技术，对安塞地区长9储层开展系统的微观孔喉结构分析，以期为该地区致密油藏的优化开发提供科学依据和实践指导。

2．区域地质背景

鄂尔多斯盆地位于华北克拉通西部，安塞油田地处盆地伊陕斜坡中东部，构造上表现为东倾西缓的大型单斜，受差异压实作用影响，发育一系列南北向展布的鼻隆构造

[7, 8]

。

研究区上三叠统延长组为主要产层，与下伏纸坊组及上覆富县组、延安组呈平行不整合接触

[9]

。该组自下而上划分为10个油层组（长1-长10）

[10]

，其中长9段厚80-120m，呈现东厚西薄的特征，岩性以深灰-灰色细粒砂岩与灰黑色粉砂岩、泥岩不等厚互层为主，属浅水三角洲前缘沉积

[11-13]

。

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Figure 1. 图1 安塞油田构造位置及延长组长9地层综合柱状图。

3．储层基本特征

3.1．岩石学特征

手标本和铸体薄片观察显示，安塞油田长9储层以细粒长石砂岩为主，含少量岩屑长石砂岩。碎屑组分含量为75%-95%，其中石英（26%-37%）以单晶为主，长石（35%-49%）以钾长石占优，岩屑（0.1%-4%）主要为变质岩岩屑。填隙物含量较低（2%-17%），以胶结物为主，含少量杂基。胶结物类型多样，包括碳酸盐（以铁方解石为主，平均5.56%）、硅质（石英次生加大边）及自生粘土矿物（0.1%-5%），其中伊利石（3.16%）、绿泥石（2.53%）和高岭石（1.57%）为主要类型。碎屑颗粒粒径0.25-0.625mm，磨圆度以次圆-次棱角状为主，分选良好。颗粒接触关系以线接触为主，局部见点-线接触，胶结类型主要为接触式和薄膜式。

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Figure 2. 图2 安塞油田长9储层砂岩分类三角图。

I-石英砂岩；II-长石石英砂岩；Ⅲ-岩屑石英砂岩；Ⅳ-长石砂岩；Ⅴ-岩屑长石砂岩；Ⅵ-长石岩屑砂岩；Ⅶ-岩屑砂岩

3.2．物性特征

安塞油田长9储层的孔隙度介于2.49%~15.33%，平均7.72%；渗透率介于0.017mD~0.281mD，平均0.123mD，物性相关性好（图3）。根据国家能源局制定的SY/T6285-2011油气储层分类标准，认为鄂尔多斯盆地安塞油田长9储层属于典型的特低孔-超低渗透致密砂岩储层。

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Figure 3. 图3 安塞油田长9储层孔隙度与渗透率关系。

3.3．储集空间类型

3.3.1．孔隙类型

铸体薄片及典型样品扫描电镜观察显示，安塞油田长9储层主要发育残余粒间孔、溶蚀孔及少量晶间孔，面孔率为0.1%-5.0%。

残余粒间孔为成岩演化过程中碎屑颗粒间残留孔隙，形态多样（图4a）。石英颗粒间孔隙多呈三角状或多角状，孔径5-100μm；长石及岩屑颗粒间孔隙呈狭长形或多边形（图4b），孔径10-70μm。残余粒间孔面孔率0.1%-4.0%，平均1.32%；溶蚀孔隙包括粒内溶孔、粒间溶孔及晶间孔。粒内溶孔以长石溶孔为主，溶蚀强烈时呈不规则状或蜂窝状（图4c），孔径5-50μm；岩屑溶孔多呈筛状，孔径1-20μm。粒间溶孔包括残余孔隙溶蚀扩大型及新生溶蚀型，孔径10-60μm。晶间孔发育较少，孔径小于1μm。溶蚀孔隙面孔率0.3%-2.2%，平均0.89%；微裂缝发育，宽度1-10μm，长度200μm-1mm，面孔率0.1%-1.0%，平均0.56%，为重要的储集空间和渗流通道（图4d）。

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Figure 4. 图4 安塞油田长9储层显微特征。

a. 残余粒间孔与溶蚀孔，单偏光；b.石英与长石颗粒，单偏光；c. 梳状长石溶蚀孔，单偏光；d. 微裂缝，单偏光

3.3.2．喉道类型

喉道作为孔隙间的连通通道，其形态与规模是控制储层渗流能力的关键因素

[14, 15]

。安塞油田长9致密砂岩储层以片状、弯片状和管束状喉道为主，缩颈状和点状喉道次之。

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Figure 5. 图5 安塞油田长9储层孔喉发育镜下特征。

a.片状、弯片状喉道，单偏光；b.管束状喉道，单偏光；c.缩颈型喉道；d.点状喉道，单偏光

片状和弯片状喉道主要受机械压实作用控制，表现为碎屑矿物定向重排，颗粒间呈线接触或凹凸接触，喉道形态多被压扁呈狭长条状（图5a）。管束状喉道由蠕虫状高岭石充填孔隙后分割形成，呈毛管状或束状，显著降低了储层连通性（图5b）。缩颈状喉道发育于矿物颗粒窄小处，颗粒多呈点接触，胶结物不发育，表明压实作用较弱，孔喉连通性良好（图5c）。

点状喉道（孔缩型喉道）由碎屑矿物经压实-溶蚀作用形成，颗粒间呈点接触，骨架支撑结构松散（图5d）。该类型喉道与相邻孔隙差异显著，非均质性强，具有大孔粗喉特征，流体流动阻力小，是致密砂岩储层"甜点"区的标志

[16]

。

4．致密砂岩储层微观孔喉结构综合评价

致密砂岩储层孔隙系统具有纳米至微米级连续分布特征，单一实验方法难以全面表征其孔径分布

[17, 18]

。本文采用多方法联合表征：通过图像孔隙法分析二维孔隙分布特征，结合高压压汞和恒速压汞实验区分孔隙与喉道，利用核磁共振测试确定可动流体孔喉半径下限，并借助纳米CT扫描技术直观呈现。

4.1．基于图像孔隙法的孔喉二维平面分布特征

基于铸体薄片与数字图像分析技术，对安塞油田长9储层22个样品进行图像孔隙分析，获取了孔径、孔隙配位数、比表面积、均质系数、形状因子、孔喉比及分选系数等关键参数（表2），系统评价了储层孔喉结构的二维特征。

分析结果表明，长9储层致密砂岩平均孔隙半径为21.51μm（15.28-24.98μm），平均比表面积为0.35μm^-1（0.21-0.5μm^-1），平均孔喉比为6.95（1.06-13.63）。孔隙配位数为0.18（0.02-0.50），分选系数为4.45（2.61-6.37），均质系数为0.61（0.5-0.74）。

表1 安塞油田长9储层基于图像孔隙法的孔喉特征。

参数	平均孔隙半径/μm	孔隙结构参数
参数	平均孔隙半径/μm	平均比表面/μm^-1	平均形状因子	平均配位数	平均孔喉比	分选系数	均质系数
最大值	24.98	0.50	0.85	0.50	13.63	6.37	0.74
最小值	15.28	0.21	0.49	0.02	1.06	2.61	0.50
平均值	21.51	0.35	0.70	0.18	6.95	4.45	0.61

长9储层致密砂岩平均孔隙半径主要分布于10.0-30.0μm的小孔范围。比表面积和平均形状因子与孔隙半径呈负相关，表明微孔隙发育较少。孔隙配位数与孔隙半径呈正相关，反映大孔隙连通性较好，有利于提高储层渗透率。孔喉比和分选系数与孔隙半径呈正相关，而均质系数呈负相关，表明储层孔隙非均质性强，孔径差异显著。这种孔隙分布特征对改善储层储渗性能具有重要作用，是优质储层发育的关键控制因素。

4.2．基于压汞实验的储层微观孔喉特征

4.2.1．高压压汞曲线特征

高压压汞实验结果表明，长9储层样品毛管压力曲线形态差异显著，对应不同的微观孔喉结构参数（表2）。基于毛管压力曲线特征及孔喉结构参数，将储层划分为两类（图6）。

表2 安塞油田长9储层高压压汞实验特征参数。

分类		孔隙度（%）	渗透率（md）	平均孔喉半径(μm)	最大孔喉半径(μm)	孔喉半径中值(μm)	排驱压力(MPa)	中值压力 (MPa）	最大汞饱和度 (%)	退出效率（%）	分选系数	歪度
I类	最大值	15.17	0.30	0.13	0.54	0.12	2.74	26.99	96.61	31.46	2.49	0.28
	最小值	6.50	0.11	0.07	0.27	0.03	1.36	6.67	77.96	17.47	1.49	0.02
	平均值	10.46	0.23	0.11	0.45	0.07	1.82	15.29	84.87	26.46	2.06	0.18
II类		3.92	0.03	0.02	0.05	0.09	13.78	5.82	34.45	16.79	1.15	0.21

I类样品毛管压力曲线平缓，排驱压力较低（平均1.82MPa），中值压力15.29MPa（6.67-26.99MPa），最大孔喉半径约0.45μm。曲线特征表明孔喉连通性由好变差，分选系数2.06，歪度0.18，反映孔喉分选中等偏差。该类样品孔隙度10.46%（6.5%-15.17%），渗透率0.23mD（0.11-0.3mD），物性较好，为储层主要类型。

II类样品毛管压力曲线平缓段缺失，排驱压力13.78MPa，中值压力5.82MPa，最大进汞饱和度34.45%，最大孔喉半径0.05μm。分选系数1.15，歪度0.21，表明孔喉分选较好。该类样品孔隙度3.92%，渗透率0.03mD，物性较差，退汞效率低，指示细孔大喉发育。

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Figure 6. 图6 安塞油田长9储层样品高压压汞曲线分类特征图。

4.2.2．高压压汞孔径分布

安塞油田长9储层孔喉半径分布范围为0.004-0.4μm，非均质性显著（图7）。根据Sing（1984）和IUPAC分类标准

[19]

，孔喉主要分布于微孔-大孔范围。渗透率贡献量呈正态分布，峰值集中于0.01-0.1μm孔喉半径区间（图7）。半径小于0.004μm和大于0.1μm的孔喉对渗透率贡献较小。由于高压压汞实验难以区分孔隙与喉道，该峰值可能反映两种孔喉结构特征：一是0.01-0.1μm孔隙集中发育；二是该尺度喉道控制的孔隙体积较大。

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Figure 7. 图7 安塞油田长9储层基于渗透率贡献量的孔喉半径分布特征。

4.2.3．恒速压汞曲线特征

针对物性差、孔喉结构复杂且非均质性强的致密砂岩储层，常规压汞实验难以区分孔隙与喉道的储渗贡献差异

[20]

。本文通过恒速压汞实验，系统刻画了安塞油田长9储层孔喉结构特征，揭示了孔隙与喉道对储层质量的差异性影响。

实验结果表明（表3），样品排驱压力平均3.98MPa（2.91-4.87MPa），最终进汞饱和度24.30%（14.49%-31.78%）。其中，孔隙进汞饱和度4.43%（1.96%-6.14%），喉道进汞饱和度19.87%（12.53%-26.59%），孔喉半径比平均703（595-916）。

表3 安塞油田长9储层恒速压汞法实验参数。

参数	孔隙度	渗透率	排驱压力	最终进汞饱和度	总孔隙进汞饱和度	总喉道进汞饱和度	孔隙半径平均值	最大连通喉道半径	喉道半径平均值	孔喉半径比平均值
	Φ	K	Pd	S_f	S_b	S_t	γ_p	R_max	γ_t	η
	%	mD	MPa	%	%	%	μm	μm	μm
最大值	7.80	0.16	4.87	31.78	6.14	26.59	149.87	0.25	0.33	916.59
最小值	5.38	0.07	2.91	14.49	1.96	12.53	132.32	0.15	0.16	595.05
平均值	6.72	0.11	3.98	24.30	4.43	19.87	140.58	0.19	0.25	703.76

长9储层样品孔隙半径分布曲线形态相似（图8a），主峰位于140μm，主要分布于100-250μm。喉道半径呈正态分布（图8b），排驱压力与喉道半径呈负相关，主要分布于0.1-1μm，平均0.16-0.33μm。半径小于0.15μm的喉道含量极少，表明恒速压汞对该尺度孔喉表征存在局限。

样品总进汞饱和度较低，渗流能力弱，且喉道进汞饱和度显著高于孔隙进汞饱和度，表明喉道控制渗流能力。孔喉比（65-1955）异常高（图8c），反映孔隙粗大而喉道细小，导致渗透率低、渗流能力差。

安塞油田长9储层喉道对渗透率的贡献率分布集中（图8），峰值对应的喉道半径为0.08-0.15μm，较喉道频率峰值（0.15-0.2μm）略向左偏移，表明储层渗透率主要受较小半径喉道控制。

4.2.4．联合压汞法表征孔径分布特征

基于高压压汞与恒速压汞实验数据，构建孔喉半径分布频率叠合图（图9），以1μm为界划分为喉道区（0.006-1.00μm）和孔隙区（60-270μm）。喉道区分布频率峰值小于30%（27%），对储层影响较小；孔隙区分布频率峰值大于30%（35.3%），对储层影响显著。

研究区样品孔喉半径分布特征相似，主要发育0.15μm左右的喉道和120μm左右的孔隙。喉道半径分布范围为0.006-1μm，孔隙半径分布范围为60-270μm。

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Figure 8. 图9 高压压汞-恒速压汞联合评价安塞油田长9储层孔喉半径分布频率叠合图。

4.3．基于核磁共振法探究储层微观孔喉特征

基于核磁共振

T_{2}

谱分析，结合离心实验确定T₂截止值（T_2cutoff），系统表征了安塞油田长9储层微观孔喉结构及可动流体赋存特征，并通过经验公式计算了可动流体孔喉半径及等效球孔喉半径。

4.3.1．可动流体孔喉半径下限计算

核磁共振实验结果表明，安塞油田长9储层核磁孔隙度平均6.13%（5.49%-6.94%），渗透率平均0.08mD（0.02-0.2mD）。可动流体孔隙度平均1.6%（1.23%-1.97%），T2截止值平均80.31ms（27.25-167.94ms），束缚水饱和度平均74.16%（71.63%-77.62%）。

长9储层

T_{2}

谱呈明显双峰特征（图10），弛豫时间分布范围为0.1-1000ms。根据

T_{2}

谱形态特征，将孔隙结构划分为两类：I类（右峰高于左峰）和II类（左峰高于右峰），其中以I类为主。

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Figure 9. 图10 安塞油田长9储层典型核磁共振T₂谱图。

核磁共振弛豫时间与可动流体孔喉半径呈正相关。I类样品大孔喉发育程度高，体积占比大，孔喉连通性好，流体流动性强，储层物性优；II类样品小孔喉发育为主，孔喉连通性差，流体流动性弱，储层物性较差。

离心实验表明（图11），长9储层可动水孔隙度为1.27%-1.98%，远低于不可动水孔隙度（4.23%-4.98%），反映小孔径孔隙占主导。可动水与不可动水孔隙度比值为0.30-0.39，表明储层孔喉连通性和渗流能力较差。基于T₂谱分布，将左、右峰分别定义为小、大孔喉。离心后孔隙度分量显著降低，其中大孔降幅更大，结合铸体薄片观察，表明可动流体主要赋存于大孔喉（粒间孔和溶蚀孔），而束缚水主要存在于小孔喉（黏土矿物晶间孔）。

根据

T_{2}

横向弛豫时间与孔隙半径R之间的转换关系式，计算可动流体的孔隙半径下限：

R = C T_{2}^{1 / n}

C代表转换系数，鄂尔多斯盆地低孔超低渗致密砂岩储层的C值取经验值0.013；n取值0.7842。计算得出可动流体孔隙半径下限为0.88-8.94μm。随着孔隙度增大，可动流体孔隙半径下限值增加，表明储层物性与可动流体孔隙半径呈正相关，孔隙半径越大，储层品质越好。

4.3.2．等效球的孔喉半径计算

基于球管模型

[21-23]

，建立核磁共振T₂谱与喉道半径的转换关系：

R = ρ F_{s} T_{2}

其中

R

为等效球半径，μm；

T_{2}

是横向弛豫时间，ms；

ρ

为横向弛豫率，μm/ms，

F_{s}

为孔隙形状因子。当

\sqrt{K/φ} ＜ 0.5

时（K-渗透率，10^-3μm²；φ-孔隙度，%），

ρ

取3.2×10^-6μm/ms；0.5≤

\sqrt{K / φ}

＜1.0时，

ρ

取2.5×10^-6μm/ms。

计算结果表明，长9储层喉道半径为0.16-0.67μm，反映孔喉偏细小。恒速压汞与核磁

T_{2}

谱数据相关性分析显示，孔隙半径均值与

T_{2}

弛豫时间的相关系数为0.91，喉道半径均值与

T_{2}

弛豫时间的相关系数为0.81，表明核磁共振可有效补充表征致密砂岩孔喉结构特征。

4.4．基于纳米CT法的储层裂隙特征

二维图像显示，样品在微米尺度上呈现强非均质性（图12）。典型样品整体致密（图12a、b），发育少量微孔和粒内孔，主要储集空间为粒间孔（图12c）、黏土充填/半充填粒间残余孔、石英长石粒内溶孔、黏土矿物晶间孔及石英长石颗粒间压溶缝（图12d）。

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Figure 10. 图12 安塞油田长9储层样品扫描电镜下储集空间。

a. 样品X-001的MAPS扫描，扫描电镜；b. 样品X-002的MAPS扫描，扫描电镜；c.未被充填的粒间孔，扫描电镜；d.压溶缝，扫描电镜

基于Avizo软件，采用滤波算法增强信噪比，结合图像分割技术对三维纳米CT灰度图像进行二值化处理，识别孔喉与裂隙结构。通过区域渲染获得二值化分割图像（图13），其中蓝色区域代表孔隙，紫色区域代表裂缝，为孔隙网络模型构建提供基础数据。

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Figure 11. 图13 安塞油田长9储层基于纳米CT法的岩心3D模型图。

a. 样品X-001的孔喉模型三维图；b. 样品X-002的孔喉模型三维图；c. 样品X-001的裂缝模型三维图；d. 样品X-002的裂缝模型三维图

基于孔喉网络和连通性模型分析，样品X-001物性较好，孔喉半径0.53-1.56μm，裂缝宽度0.18-4.80μm，其中0.51μm裂缝占比超30%；样品X-002物性较差，孔喉半径0.39-1.38μm，裂缝宽度0.07-1.22μm，0.18-0.30μm裂缝占比超20%。典型样品孔喉半径非均质性强，裂缝发育程度高，储集空间连通性较好。

4.5．联合多种手段探讨安塞油田长9储层的微观孔喉结构特征

本研究通过多方法联合表征，系统揭示了安塞油田长9储层微观孔隙结构特征。图像孔隙法有效表征了10.0-30.0μm尺度孔隙，揭示储层平均孔隙半径为21.51μm（15.28-24.98μm），孔隙半径与配位数呈正相关，与孔喉比、分选系数呈负相关，表明储层非均质性强。高压压汞与恒速压汞联合分析表明，储层主要发育0.15μm喉道（0.006-1μm）和120μm孔隙（60-270μm）。核磁共振实验确定了可动流体孔隙半径下限为0.88-8.94μm，且与物性呈正相关。基于T₂谱和等效球半径法建立的球管模型显示喉道半径为0.16-0.67μm，与压汞实验结果相互印证。纳米CT扫描揭示了裂缝发育特征（缝宽0.07-4.80μm），表明裂缝对储层物性具有重要贡献。多种实验方法的有机结合，实现了致密砂岩储层全尺度孔喉结构的系统表征，为储层评价和油气开发提供了可靠依据。

5．结论与展望

（1）安塞油田长9储层岩性以细粒长石砂岩为主，含少量岩屑长石砂岩。储集空间以残余粒间孔和溶蚀孔为主，发育少量晶间孔；喉道类型主要为片状、弯片状和管束状。

（2）多方法联合表征表明，长9储层致密砂岩平均孔隙半径21.51μm，属小孔范围。联合实验揭示储层主要发育0.15μm的喉道（0.006-1μm）和120μm的孔隙（60-270μm）。核磁共振测试确定可动流体孔隙半径下限为0.88-8.94μm，与物性呈正相关。裂缝发育集中，缝宽0.07-4.80μm，分布广泛。

（3）本研究孔喉结构表征虽覆盖多尺度，但微观参数与宏观渗流特征的关联机制尚不明确，未来需要结合数字岩心与流体模拟技术，构建储集空间-渗流能力的多物理场模型，以量化不同尺度储集空间对储层产能的控制作用。

致谢

本文为陕西省自然科学基础研究计划一般项目《孔隙型致密砂岩甜点储层形成的沉积约束》（2023-JC-QN-0.315）的阶段性成果之一。

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Xixi, W., Yue, M., Yongfeng, L., Guilin, H. (2025). Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield. Science Discovery, 13(2), 16-24. https://doi.org/10.11648/j.sd.20251302.11

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Xixi, W.; Yue, M.; Yongfeng, L.; Guilin, H. Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield. Sci. Discov. 2025, 13(2), 16-24. doi: 10.11648/j.sd.20251302.11

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Xixi W, Yue M, Yongfeng L, Guilin H. Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield. Sci Discov. 2025;13(2):16-24. doi: 10.11648/j.sd.20251302.11

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@article{10.11648/j.sd.20251302.11,
  author = {Wang Xixi and Meng Yue and Li Yongfeng and Hu Guilin},
  title = {Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield
},
  journal = {Science Discovery},
  volume = {13},
  number = {2},
  pages = {16-24},
  doi = {10.11648/j.sd.20251302.11},
  url = {https://doi.org/10.11648/j.sd.20251302.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.sd.20251302.11},
  abstract = {This study presents a comprehensive investigation of the pore-throat characteristics in the Chang 9 tight sandstone reservoir of Ansai Oilfield, Ordos Basin, utilizing an integrated multiscale characterization approach. By combining image-based pore analysis, high-pressure and rate-controlled mercury intrusion porosimetry, nuclear magnetic resonance (NMR) relaxation spectroscopy, and nano-CT three-dimensional reconstruction, we established a complete pore-throat characterization methodology spanning multiple scales.The experimental results demonstrate that the reservoir exhibits a bimodal pore-throat distribution, with an average two-dimensional pore radius of 21.51 μm. The three-dimensional pore-throat network is characterized by predominant throat sizes of 0.15 μm (ranging 0.006-1 μm) and pore sizes of 120 μm (60-270 μm). NMR analysis reveals that the lower threshold radius for movable fluids ranges from 0.88 to 8.94 μm, showing significant positive correlation with reservoir quality parameters.A well-developed microfracture network with apertures of 0.07-4.80 μm was identified, which substantially enhances the reservoir's flow capacity. The successful integration of multiple characterization techniques enables complete pore-throat structure characterization across all relevant scales in tight sandstone reservoirs.These findings provide both theoretical foundations and practical guidance for sweet spot identification, reservoir evaluation, and hydrocarbon exploration/development in tight sandstone formations. The established methodology offers valuable insights for understanding fluid storage and flow mechanisms in low-permeability reservoirs.
},
 year = {2025}
}

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TY  - JOUR
T1  - Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield

AU  - Wang Xixi
AU  - Meng Yue
AU  - Li Yongfeng
AU  - Hu Guilin
Y1  - 2025/03/31
PY  - 2025
N1  - https://doi.org/10.11648/j.sd.20251302.11
DO  - 10.11648/j.sd.20251302.11
T2  - Science Discovery
JF  - Science Discovery
JO  - Science Discovery
SP  - 16
EP  - 24
PB  - Science Publishing Group
SN  - 2331-0650
UR  - https://doi.org/10.11648/j.sd.20251302.11
AB  - This study presents a comprehensive investigation of the pore-throat characteristics in the Chang 9 tight sandstone reservoir of Ansai Oilfield, Ordos Basin, utilizing an integrated multiscale characterization approach. By combining image-based pore analysis, high-pressure and rate-controlled mercury intrusion porosimetry, nuclear magnetic resonance (NMR) relaxation spectroscopy, and nano-CT three-dimensional reconstruction, we established a complete pore-throat characterization methodology spanning multiple scales.The experimental results demonstrate that the reservoir exhibits a bimodal pore-throat distribution, with an average two-dimensional pore radius of 21.51 μm. The three-dimensional pore-throat network is characterized by predominant throat sizes of 0.15 μm (ranging 0.006-1 μm) and pore sizes of 120 μm (60-270 μm). NMR analysis reveals that the lower threshold radius for movable fluids ranges from 0.88 to 8.94 μm, showing significant positive correlation with reservoir quality parameters.A well-developed microfracture network with apertures of 0.07-4.80 μm was identified, which substantially enhances the reservoir's flow capacity. The successful integration of multiple characterization techniques enables complete pore-throat structure characterization across all relevant scales in tight sandstone reservoirs.These findings provide both theoretical foundations and practical guidance for sweet spot identification, reservoir evaluation, and hydrocarbon exploration/development in tight sandstone formations. The established methodology offers valuable insights for understanding fluid storage and flow mechanisms in low-permeability reservoirs.

VL  - 13
IS  - 2
ER  -

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Author Information

Wang Xixi

College of Geology and Environment, Xi 'an University of Science and Technology, Xi 'an, China

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Meng Yue

First Oil Production Plant of Changqing Oilfield, Yan 'an, China

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Li Yongfeng

First Oil Production Plant of Changqing Oilfield, Yan 'an, China

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Hu Guilin

First Oil Production Plant of Changqing Oilfield, Yan 'an, China

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Figure 1

Figure 1. 图 1 安塞油田构造位置及延长组长9地层综合柱状图。
Figure 2

Figure 2. 图 2 安塞油田长9储层砂岩分类三角图。
Figure 3

Figure 3. 图 3 安塞油田长9储层孔隙度与渗透率关系。
Figure 4

Figure 4. 图 4 安塞油田长9储层显微特征。
Figure 5

Figure 5. 图 5 安塞油田长9储层孔喉发育镜下特征。
Figure 6

Figure 6. 图 6 安塞油田长9储层样品高压压汞曲线分类特征图。
Figure 7

Figure 7. 图 7 安塞油田长9储层基于渗透率贡献量的孔喉半径分布特征。
Figure 8

Figure 8. 图 9 高压压汞-恒速压汞联合评价安塞油田长9储层孔喉半径分布频率叠合图。
Figure 9

Figure 9. 图1 0 安塞油田长9储层典型核磁共振T₂谱图。
Figure 10

Figure 10. 图 1 2 安塞油田长9储层样品扫描电镜下储集空间。
Figure 11

Figure 11. 图1 3 安塞油田长9储层基于纳米CT法的岩心3D模型图。

Table 1

表1 安塞油田长9储层基于图像孔隙法的孔喉特征。
Table 2

表2 安塞油田长9储层高压压汞实验特征参数。
Table 3

表3 安塞油田长9储层恒速压汞法实验参数。

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Xixi, W., Yue, M., Yongfeng, L., Guilin, H. (2025). Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield. Science Discovery, 13(2), 16-24. https://doi.org/10.11648/j.sd.20251302.11

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Xixi, W.; Yue, M.; Yongfeng, L.; Guilin, H. Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield. Sci. Discov. 2025, 13(2), 16-24. doi: 10.11648/j.sd.20251302.11

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AMA Style

Xixi W, Yue M, Yongfeng L, Guilin H. Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield. Sci Discov. 2025;13(2):16-24. doi: 10.11648/j.sd.20251302.11

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@article{10.11648/j.sd.20251302.11,
  author = {Wang Xixi and Meng Yue and Li Yongfeng and Hu Guilin},
  title = {Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield
},
  journal = {Science Discovery},
  volume = {13},
  number = {2},
  pages = {16-24},
  doi = {10.11648/j.sd.20251302.11},
  url = {https://doi.org/10.11648/j.sd.20251302.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.sd.20251302.11},
  abstract = {This study presents a comprehensive investigation of the pore-throat characteristics in the Chang 9 tight sandstone reservoir of Ansai Oilfield, Ordos Basin, utilizing an integrated multiscale characterization approach. By combining image-based pore analysis, high-pressure and rate-controlled mercury intrusion porosimetry, nuclear magnetic resonance (NMR) relaxation spectroscopy, and nano-CT three-dimensional reconstruction, we established a complete pore-throat characterization methodology spanning multiple scales.The experimental results demonstrate that the reservoir exhibits a bimodal pore-throat distribution, with an average two-dimensional pore radius of 21.51 μm. The three-dimensional pore-throat network is characterized by predominant throat sizes of 0.15 μm (ranging 0.006-1 μm) and pore sizes of 120 μm (60-270 μm). NMR analysis reveals that the lower threshold radius for movable fluids ranges from 0.88 to 8.94 μm, showing significant positive correlation with reservoir quality parameters.A well-developed microfracture network with apertures of 0.07-4.80 μm was identified, which substantially enhances the reservoir's flow capacity. The successful integration of multiple characterization techniques enables complete pore-throat structure characterization across all relevant scales in tight sandstone reservoirs.These findings provide both theoretical foundations and practical guidance for sweet spot identification, reservoir evaluation, and hydrocarbon exploration/development in tight sandstone formations. The established methodology offers valuable insights for understanding fluid storage and flow mechanisms in low-permeability reservoirs.
},
 year = {2025}
}

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TY  - JOUR
T1  - Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield

AU  - Wang Xixi
AU  - Meng Yue
AU  - Li Yongfeng
AU  - Hu Guilin
Y1  - 2025/03/31
PY  - 2025
N1  - https://doi.org/10.11648/j.sd.20251302.11
DO  - 10.11648/j.sd.20251302.11
T2  - Science Discovery
JF  - Science Discovery
JO  - Science Discovery
SP  - 16
EP  - 24
PB  - Science Publishing Group
SN  - 2331-0650
UR  - https://doi.org/10.11648/j.sd.20251302.11
AB  - This study presents a comprehensive investigation of the pore-throat characteristics in the Chang 9 tight sandstone reservoir of Ansai Oilfield, Ordos Basin, utilizing an integrated multiscale characterization approach. By combining image-based pore analysis, high-pressure and rate-controlled mercury intrusion porosimetry, nuclear magnetic resonance (NMR) relaxation spectroscopy, and nano-CT three-dimensional reconstruction, we established a complete pore-throat characterization methodology spanning multiple scales.The experimental results demonstrate that the reservoir exhibits a bimodal pore-throat distribution, with an average two-dimensional pore radius of 21.51 μm. The three-dimensional pore-throat network is characterized by predominant throat sizes of 0.15 μm (ranging 0.006-1 μm) and pore sizes of 120 μm (60-270 μm). NMR analysis reveals that the lower threshold radius for movable fluids ranges from 0.88 to 8.94 μm, showing significant positive correlation with reservoir quality parameters.A well-developed microfracture network with apertures of 0.07-4.80 μm was identified, which substantially enhances the reservoir's flow capacity. The successful integration of multiple characterization techniques enables complete pore-throat structure characterization across all relevant scales in tight sandstone reservoirs.These findings provide both theoretical foundations and practical guidance for sweet spot identification, reservoir evaluation, and hydrocarbon exploration/development in tight sandstone formations. The established methodology offers valuable insights for understanding fluid storage and flow mechanisms in low-permeability reservoirs.

VL  - 13
IS  - 2
ER  -

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