Zhang Lu, Zhang Tongyao, Leng Jie, Zheng Zuhao, Qi Yumin, Tang Lei, He Wei, Yang Farong, Yin Hongchao
EnerTech-Drilling & Production Co., China National Offshore Oil Corporation, Tianjin 300452, China.
ACS Omega. 2024 May 23;9(22):23892-23902. doi: 10.1021/acsomega.4c01907. eCollection 2024 Jun 4.
Many reports have presented that in tight formation, the flow mechanism differs from a conventional reservoir, such as molecular diffusion, Pre-Darcy flow behavior, and stress sensitivity. However, for CO Huff-n-Puff development, it is a challenge to synthetically research these mechanisms. Considering the above flow mechanisms and offshore engineering background, the development plan optimization becomes a key issue. In this paper, a self-developed simulator that satisfies research needs is introduced. Then, based on experimental results, the simulation is launched to analyze the effects of CO diffusion, Huff-n-Puff period, and permeability heterogeneity. The results indicate that molecular diffusion makes a positive contribution to the oil recovery factor. Additionally, for offshore reservoirs, limited to the development cost and CO facilities corrosion, when the total Huff-n-Puff time is constant, the ratio of 0.5-1.0 between the Huff period and the Puff period in every cycle performs better. Finally, the greater heterogeneity in permeability is much more favorable for the CO Huff-n-Puff because of more intensive transport processes in formation. These different scenarios can increase the understanding of the CO Huff-n-Puff in tight oil offshore reservoirs.
许多报告指出，在致密地层中，渗流机理与常规油藏不同，如分子扩散、非达西渗流行为和应力敏感性。然而，对于二氧化碳吞吐开发而言，综合研究这些机理具有挑战性。考虑到上述渗流机理和海洋工程背景，开发方案优化成为关键问题。本文介绍了一款满足研究需求的自主研发模拟器。然后，基于实验结果进行模拟，分析二氧化碳扩散、吞吐周期和渗透率非均质性的影响。结果表明，分子扩散对采收率有积极贡献。此外，对于海上油藏，受开发成本和二氧化碳设施腐蚀的限制，当总吞吐时间恒定时，每个周期中注气周期与采气周期之比为0.5 - 1.0时效果更佳。最后，渗透率非均质性越强，对二氧化碳吞吐越有利，因为地层中的传输过程更强烈。这些不同情况有助于加深对海上致密油藏二氧化碳吞吐的理解。
