# Experimental Study on Fluid Dissipation Effects in Core Samples by NMR Measurement
## 6 Conclusions  
Through physical simulation experiments, the dissipation process of pore fluids within sandstone cores was investigated, elucidating the dissipation patterns of core pore fluids at various exposure durations.  
1. In the initial phase of exposing saturated cores, fluid dissipation predominantly occurs at the core surface. The fluid adhering to the surface rapidly dissipates into the atmosphere, resulting in a significant reduction in core weight. This process continues for approximately two hours.
2. Following the loss of surface fluid, the fluid within the core transitions into a stable dissipation phase. During this phase, the dissipation rate of bounding water is markedly higher than that of crude oil. By the conclusion of the second phase, bounding water  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Oil Viscosity**} & \multirow{2}{*}{**4-h T2 (ms)**} & \multirow{2}{*}{**4-h T1 (ms)**} & \multirow{2}{*}{**4-h T1/T2**} & \multirow{2}{*}{**96-h T2 (ms)**} & \multirow{2}{*}{**96-h T1 (ms)**} & \multirow{2}{*}{**96-h T1/T2**} \\  & **(mPas)** & & & & & & \\ \hline A & 42 & 16.3 & 60.2 & 3.7 & 14.6 & 60.2 & 4.6 \\ B & 420 & 6.8 & 67.1 & 9.87 & 4.6 & 58.0 & 12.61 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Changes in relaxation times of crude oil components in rock cores.  
Figure 10: Two-dimensional NMR experimental results of each core fluid component in the second stage of fluid dissipation: (**a**) the NMR measurement result after 4 h of exposure treatment for Sample A; (**b**) the NMR measurement result after 96 h of exposure treatment for Sample A; (**c**) the NMR measurement result after 4 h of exposure treatment for Sample B; and (**d**) the NMR measurement result after 96 h of exposure treatment for Sample B.  
is nearly entirely dissipated, leaving primarily crude oil. The dissipation rate of each fluid exhibits a logarithmic relationship with time, and this phase spans several hours to several tens of hours.
3. The third phase constitutes the stabilization phase, commencing after 96 h. During this phase, crude oil within the core dissipates into the atmosphere at a reduced rate. This phenomenon arises due to the inherent differences in the physical and chemical properties of crude oil and bounding water. Bounding water, being less viscous and having smaller molecular size, can more readily diffuse through the interconnected pore network and evaporate.
4. This study offers a qualitative reference for the dissipation patterns of fluids under ambient temperature conditions, focusing on sandstone cores saturated with crude oil of specific viscosity. To quantitatively assess the dissipation patterns of various lithologies and crude oils with differing viscosities under diverse temperature and humidity conditions, further comprehensive experimental research is necessary.  
The authors confirm their contributions to the paper as follows: Conceptualization and design, G.Z.; data collection, Z.L. and Y.M.; analysis and interpretation of results, G.Z., Z.L. and Y.M.; draft manuscript preparation, Z.L. All authors have read and agreed to the published version of the manuscript.  
The authors received no specific funding for this study.  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
The authors would like to thank the reviewers and academic editors for their useful suggestions for improving the quality of our manuscript.  
The authors declare that they have no conflicts of interest to report regarding the present study.