摘要：Understanding the occurrence state and microscopic distribution of bound water, as well as the factors governing bound water saturation and its impact on natural gas flow within nano-scaled pore networks, holds significant importance for reservoir evaluation, productivity prediction, and production. However, the complexity of pore structure poses a challenge in quantitatively characterizing these aspects, and currently, no effective method exists to achieve this characterization. This study takes the Bashijiqike tight sandstone of the Kuqa Depression of the Tarim Basin as an example; by integrating physical property test, XRD, microscopic observation with casting thin section and SEM, HPMI, NMR, and NMR-supervised gas-charging experiment, proposed a novel bound water occurrence model to depict the microscopic distribution of bound water in nano-scaled pore space. Furthermore, the impact of bound water on gas-flowing behaviors was thoroughly examined and the complex relationships between bound water saturation and reservoir macroscopic and microscopic parameters were explored. In addition, based on the grey relational analysis, the critical controlling factor on bound water saturation were screened out. The bound water in the pore space of tight sandstone comprises two components: capillary-bound water within small pores (rcutoff). The water-film within large pores is non-uniform, non-isothick, and low in content. During gas charing to reservoirs, the water-film thickness decreased gradually as the charging force increased, with a minimum thickness ranging from 0.10 to 3.72 nm. Water-film accounted for 1.75% to 22.96% of the total bound water content, with an average of 7.28%. In contrast to previous studies, we found that water-film had a negligible impact on the minimum pore/throat radius for gas charging, with only an increase of 0.7 nm. However, it significantly altered the physical characteristics, reducing gas permeability from 46.11% to 97.84%, with an average reduction of 78.37%. Furthermore, a water-film effectively eradicated the slip effect, leading to the prevalence of Darcy and diffusion flow as the primary mechanisms for gas seepage. At low pressure, diffusion flow prevails, whereas Darcy flow dominates at high pressure. I/S-mixed layer and illite exert the most significant influence on bound water saturation. ? 2023 Elsevier Ltd

ISSN号：0016-2361

卷、期、页：卷357子辑C

发表日期：2024-02-01

期刊分区（SCI为中科院分区）：一区

收录情况：SCI（科学引文索引印刷版）,EI（工程索引）,SCIE（科学引文索引网络版）

发表期刊名称：Fuel

参与作者：何元元,张月巧,Lobusev, M.A.

通讯作者：吕明阳,赵力彬,刘常祺

第一作者：宋泽章

论文类型：期刊论文

论文概要：宋泽章,吕明阳,赵力彬,刘常祺,何元元,张月巧,Lobusev, M.A.，A novel bound water occurrence model for tight sandstone，Fuel，2024，卷357子辑C

论文题目：A novel bound water occurrence model for tight sandstone