地层压力随钻测试压力响应的数值模拟与物模实验

It is very important to get the formation pore pressure accurately and on time for the project of Deep Earth Exploration, such as the scientific drilling, deep well drilling, petroleum exploitation, geothermal development, CO2 geological sequestration and nuclear waste disposal. Accounting for the current main problems of formation pressure testing while drilling (FPWD), the present work intended to conduct the fluid-solid-heat coupling experiments for sandstone with different permeability, to propose the constitutive model of sandstone under fluid-solid-heat coupling, and to investigate the distribution characteristics and evolution law of pore pressure around the borehole. The physical model simulation of pressure response for FPWD will be carried out to investigate the influence of formation environment, wellbore environment and suction parameters on the pressure response for FPWD. The numerical simulation method of fluid-solid-heat coupling will be proposed for FPWD to simulate the influence of different influencing factors on the pressure response, and to conduct the optimal design of suction system, calibration of FPWD tool, and interpretation of FPWD data. The present work has an important role for more accurate testing of formation pore pressure, speeding up the development process of China's FPWD instruments. The present work also has very important practical significance for achieving the target of Deep Earth Exploration.

准确及时获取地层压力参数对科学钻探、深井钻井、油气开采、地热开采、CO2地质埋存和核废料地质处置等深部地球探测工程具有十分重要的意义。针对地层压力随钻测试存在的主要问题，拟通过不同渗透率砂岩的流-固-热耦合实验，建立砂岩流-固-热耦合本构模型，研究井周孔隙压力分布特征和演化规律；开展地层压力随钻测试压力响应物模实验，研究地层环境、井筒环境和抽吸参数影响下的压力响应特征；建立地层压力随钻测试压力响应的流-固-热耦合数值模拟方法，模拟不同影响因素对压力响应的影响规律，进而开展抽吸系统优化设计、地层压力随钻测试仪器刻度、地层压力随钻测试数据解释研究。研究成果将有助于更加准确测试地层孔隙压力，有助于加速我国地层压力随钻测量仪器的研发进程，对于实现深部地球探测目标具有重要的现实意义。

本项目以地层压力随钻测试压力响应问题为研究对象，研究了钻井过程中井周围岩流-固-热耦合机理，建立了井周孔隙压力流-固-热耦合模型，明确了井周孔隙压力分布特征及其演化规律；开展了地层压力随钻测试抽吸物理模型实验，揭示了地层环境、井筒环境和抽吸参数对压力响应的影响规律；基于动量守恒、质量守恒和能量守恒，综合考虑井壁泥饼增长、钻井液侵入、井周增压以及流-固-热耦合过程，建立了流-固-热全耦合下的随钻地层压力测试压力响应数学模型，推导了控制方程的有限元弱形式和离散格式，采用弱形式PDE自定义模块进行二次开发，实现了对流-固-热耦合有限元模型的数值求解，利用物理模型实验结果验证了有限元模型的准确性；最后，分析了流-固-热耦合作用下地层压力随钻测试压力响应行为，揭示了地层环境、井筒环境和抽吸参数对压力响应的影响规律，并开展了地层参数反演和地层压力测试抽吸参数优化等应用研究。本项目研究结果有利于改善随钻地层压力测试精度和时效性，对于保障钻井作业安全、加速随钻地层测试仪器研发、实现深部地球探测目标具有重要意义。