深水浅层钻井液水合物抑制性能优化

深水浅层地质条件复杂，土质疏松、作业压力窗口窄、海底泥线温度低、井筒内易生成水合物，钻井液面临着井壁稳定、低温流变性调控难度大以及环境污染等问题，钻井安全作业风险高。为此，以南海某深水井浅层钻井为研究对象，总结分析了深水浅层钻井液应用现状，建立了深水浅层钻进ECD计算模型和井筒温度场计算模型，分析了深水浅层钻井期间的井筒温度场分布规律和水合物生成风险，结合数值模拟和室内实验，进行了浅层钻井液体系水合物抑制性能优化。研究结果表明，建立的深水浅层钻进ECD计算模型和井筒温度场计算模型，与实测数据对比模型计算平均误差小于8%；计算得出深水浅层钻进期间井筒水合物生成区域范围随着钻井深度的增加逐渐减小，但钻进准备期间及钻进初期，井筒内仍存在水合物生成风险；常规半防钻井液体系优化为HEM+14%NaCl+6%KCl，可满足正常钻进期间作业需求。结论认为:通过深水浅层钻井液体系优化，可以减少钻井液体系中水合物抑制剂的加入，简化钻井液配方，降低钻井成本，提高作业效率，为深水油气钻探钻井液设计提供指导。 

Optimization of Hydrate Inhibition Performance of Deep Water Shallow Drilling Fluid

The deep water and shallow geological conditions are complex, the soil is loose, the operating pressure window is narrow, the submarine mud line temperature is low, and hydrates are easy to form in the well bore. The drilling fluid is faced with problems such as well bore stability, difficulty in regulating low-temperature rheology, environmental pollution and so on, so the drilling safety operation risk is high. Therefore, taking the shallow drilling of a deep water well in the South China Sea as the research object, the application status of deep-water shallow drilling fluid are summarized and analyzed, the ECD calculation model and well bore temperature field calculation model is established, and the well bore temperature field distribution and hydrate formation risk during deep-water shallow drilling is analyzed. The hydrate inhibition performance of shallow drilling fluid system is optimized in combination with numerical simulation and indoor experiments. The following research results are obtained. First, compared with the measured data, the average error of ECD calculation model and well bore temperature field calculation model for deep-water shallow drilling is less than 8%; Second, it is calculated that the range of hydrate formation area in the well bore gradually decreases with the increase of drilling depth, but there is still a risk of hydrate formation in the well bore during drilling preparation and early drilling; Third, the conventional semi preventive drilling fluid system is optimized as HEM+14%NaCl+6%KCl, which can meet the operation requirements during normal drilling. It is concluded that through the optimization of deep water shallow drilling fluid system, the addition of hydrate inhibitor can be reduced, the drilling fluid formula can be simplified, the drilling cost can be reduced, and the operation efficiency can be improved, which can provide guidance for the drilling fluid design of deep water oil and gas drilling.