Combining rate-controlled porosimetry and NMR to probe full-range pore throat structures and their evolution features in tight sands: A case study in the Songliao Basin, China
Combining rate-controlled porosimetry and NMR to probe full-range pore throat structures and their evolution features in tight sands: A case study in the Songliao Basin, China
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结合速率控制孔隙率和核磁共振探测致密砂岩全范围孔喉结构及其演化特征：以中国松辽盆地为例
DOI：
10.1016/j.marpetgeo.2017.03.003
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发表时间：
2017-05-01
影响因子：
4.2
通讯作者：
Lu, Shuangfang
中科院分区：
文献类型：
--
作者：
Xiao, Dianshi;Jiang, Shu;Lu, Shuangfang
为了更好地理解储层质量并做出准确的岩石物理解释，有必要了解致密砂岩中复杂且非均质性的孔喉结构，并开发一种能够揭示全范围孔隙和喉道分布的技术。在本研究中，为了表征孔喉结构的特征及演化，对中国松辽盆地白垩系下统致密气砂岩的9个样品进行了核磁共振（NMR）、速率控制孔隙度测定（RCP）和扫描电子显微镜（SEM）测量。在这些致密砂岩中发现了具有双分形结构的喉道，利用RCP数据可将其分为主干形成（BF）区域和渗流区域。由于（i）渗流区域的喉道记录了树状孔隙结构，且在小孔隙空间中占主导地位；（ii）由NMR得出的T - 2弛豫时间与由RCP得出的喉道半径之间存在良好的相关性，因此通过RCP获得的喉道分布可用于校准NMR孔隙尺寸分布（PSD），进而将PSD划分为孔隙体和喉道的分布。这些数据表明（i）在渗透率较低的致密砂岩孔隙空间中，喉道比孔隙体更为常见；（ii）孔隙体与来自BF和渗流区域的喉道相连，其中孔隙体中的流体流动性主要受孔喉比（PTR）控制，该比值与这两个区域的交叉喉道有关；（iii）压实作用、溶解作用、粘土胶结作用以及沉积特性（例如岩石成分）对孔隙体和喉道的演化具有不同的影响，其中致密砂岩中较大的PTR值主要由压实作用和孔隙桥接粘土胶结作用产生，而孔隙体含量较低通常与大量塑性成分和孔隙桥接粘土胶结作用有关。（C）2017爱思唯尔有限公司。保留所有权利。
To better understand reservoir quality and to produce accurate petrophysical interpretations, it is necessary to understand complex and heterogeneous pore throat structures in tight sands and to develop a technique to reveal the full range of pore and throat distributions. In this study, in order to characterize the features and evolutions of pore throat structures, nine samples from the Lower Cretaceous tight gas sandstone in the Songliao Basin of China are measured by nuclear magnetic resonance (NMR), rate controlled porosimetry (RCP) and scanning electron microscopy (SEM). Throats with bifractal structures are found in these tight sands and can be divided into a backbone formation (BF) region and a percolation region using RCP data. Because (i) throats in the percolation region record treelike pore structures and are predominant in small pore spaces and (ii) a good correlation exists between NMRderived T-2 relaxation times and the RCP-derived radius of throats, the throat distribution obtained via RCP can be used to calibrate the NMR PSD and then to partition the PSD into distributions of pore bodies and throats. These data indicate that (i) throats are more common than pore bodies in pore spaces of tight sands with lower permeability, (ii) pore bodies are connected to throats from both the BF and percolation regions, in which the fluid mobility in pore bodies is mainly controlled by the pore to throat ratio (PTR), which is related to the intersection throat of these two regions, and (iii) compaction, dissolution, clay cementation and sediment properties (e.g., rock compositions) have different impacts on the evolutions of pore bodies and throats, in which larger PTR values in tight sands are mainly produced by compaction and pore-bridging clay cementation, and lower contents of pore bodies are commonly related to abundant plastic compositions and pore-bridging clay cementation. (C) 2017 Elsevier Ltd. All rights reserved.