致密岩心带压渗吸规律实验研究

Forced imbibition in tight sandstone cores

江昀 许国庆 石阳 余玥 王天一 曾星航 郑伟

JIANG Yun XU Guoqing SHI Yang YU Yue WANG Tianyi ZENG Xinghang ZHENG Wei

中国石油勘探开发研究院, 北京 100083 中国石化 石油工程技术研究院, 北京 100101 中国石油 西南油气田分公司, 成都 610056

PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China SINOPEC Research Institute of Petroleum Engineering, Beijing 100101, China PetroChina Southwest Oil & Gas Field Company, Chengdu, Sichuan 610056, China

致密油藏体积改造压后闷井过程中发生的渗吸置换，通常在压差（基质外部流体压力与孔隙压力之差）作用下进行，但渗吸置换物理模拟却通常在常压下进行（即自发渗吸），带压条件下的渗吸置换特征尚未提及。为研究压差作用下的渗吸置换（即带压渗吸）规律，首先，建立基于低场核磁共振测试技术的带压渗吸实验方法；其次，分析自发/带压渗吸的异同；最后，建立带压渗吸无因次时间模型。结果表明，质量分数为96.76%~97.25%的油相集中分布于纳米孔（1 ms ≤ T2 ≤ 100 ms）内，纳米孔是主要储集空间；相比于自发渗吸，带压渗吸置换效率大幅提升是由强化的渗吸作用和压实作用共同造成的；岩心尺度建立的带压渗吸无因次时间模型可行，为确定油藏尺度压后闷井时间提供了新思路。

Spontaneous imbibition (SI) generally occurs under forced pressure (pressure difference between hydraulic fluid pressure and original pore pressure) during a shut-in period. However, the experimental study of SI is commonly performed at atmospheric pressure and the effect of forced pressure is often neglected. In this study, the mechanism of SI in tight sandstone samples under forced pressure (forced imbibition, FI) was studied. A new experimental method for forced imbibition was firstly constructed based on low-field nuclear magnetic resonance(LF-NMR) measurements. After that, a correlation between SI and FI was discussed. Finally, a new dimensionless time model considering the effect of forced pressure for FI was constructed. The results showed that 96.76%-97.25% wt% of the oil was distributed in nano-pores (0.1 ms ≤ T2 ≤ 100 ms) of core samples, occupying the major pore space. The ultimate oil recovery for FI was significantly improved relative to that of SI, which was associated with the synergetic effect of enhanced SI and compaction. The new dimensionless time model for FI was proved to be effective and it provides a new method to calculate shut-in time at field scale.

国家科技重大专项“致密油储层高效体积改造技术” 2016ZX05046-004

https://doi.org/10.11781/sysydz202101144