水合物分解对钻井液侵入影响的一维数值模拟研究

Analysis on One-dimensional Numerical Stimulation of Hydrates Dissociation Effect on Drilling Fluid Intruding into Hydrate-bearing Sediment

摘要:

海洋含水合物地层往往是具有渗透性的多孔介质体，钻井过程中钻井液不可避免地会与它发生能量和物质交换，水基钻井液驱替侵入水合物地层和温差下热传导导致的水合物分解这二者是耦合在一起的，其侵入可描述为一个包含相变的非等温非稳态渗流扩散过程。在综合分析钻井液侵入含水合物地层特性的基础上，结合水合物开采数值模拟以及常规油气藏钻井液侵入模型，建立了一维径向钻井液侵入含水合物地层的侵入模型。利用编程，分析了钻井液侵入水合物地层时地层压力、各相饱和度和温度的分布规律。

关键词:天然气水合物;钻井液侵入;数学模型;数值模拟

Abstract:

Marine gas hydrated formation is often porous and permeable. Drilling fluid will inevitably exchange the energy and materials there during the drilling process. The intrusion of water-based drilling fluid into hydrated formation and hydrate decomposition due to heat transfer by temperature difference are coupled together. The intrusion can be described as non-isothermal and unsteady percolating diffusion processes with phase transition. On the basis of comprehensive analysis on the characteristics of drilling fluid intruding natural gas hydrate-bearing formations and according to the numerical simulation of gas hydrate exploitation and conventional oil and gas reservoirs drilling fluid intrusion model, one-dimensional model of drilling fluid radial intruding into natural gas hydrate-bearing formations was established. By using the program, the analysis was made on formation pressure, saturation of each phase and the distribution of temperature while drilling fluid intruding into hydrate-bearing formation.

Key words:natural gas hydrate; drilling fluid intruding; mathematical model; numerical simulation