缅甸西海岸深水气田水基钻井液优化设计

为解决缅甸西海岸深水气田钻井面临的水敏性泥页岩井壁失稳、海底低温高压条件下钻井液增稠和易生成天然气水合物的问题,以聚胺抑制剂SDJA为关键处理剂,在优化钻井液低温流变性及优选天然气水合物抑制剂等关键处理剂的基础上,构建了强抑制性水基钻井液HIDril。室内性能评价结果表明,该钻井液具有较低的黏度和较高的动切力及6值,有利于清洗井眼,并且在温度4℃时具有良好的流变性;水敏性泥页岩回收率最高可达96.33%,抑制性能优良;在模拟海底环境的低温高压条件下,可有效抑制天然气水合物的生成;渗透率恢复率大于85.57%,具有较好的储层保护效果。在此基础上,针对缅甸西海岸深水气田不同井段的特点进行了钻井液技术方案设计,可为该深水气田钻井提供借鉴。 

Design Optimization for Water-Based Drilling Fluids in a Deepwater Gas Field on the Western Coast of Myanmar

In order to cope with the problems encountered in deepwater gas reservoir drilling on the west coast of Myanmar, such as borehole instability in water-sensitive shale formation, mud thickening at low temperature and high pressure on the seafloor, and the generation of natural gas hydrate, strong inhibitory water-based drilling fluid HIDril was optimized and designed on the basis of optimizing drilling fluid rheology at low temperature and selecting key agents including a gas hydrate inhibitor, taking polyamine inhibitors SDJA as the key agent. Indoor performance evaluation results showed that the drilling fluid of lower viscosity, higher dynamic shear and 6 value was better for hole cleaning, and at the temperature 4℃, it had good rheology. The mud displayed satisfactory performances in inhibition of hydration of water sensitive mud shale and achieved the highest recovery rate of water-sensitive shale up to 96.33%. In the simulated seabed environment with low temperatures and high pressures, HIDril could effectively inhibit the formation of gas hydrate. Drilling fluid permeability recovery rate was above 85.57%, which had a good reservoir protection effect. On this basis, drilling fluid technology program was designed according to the characteristics of different well sections in the deepwater gas field at the west coast of Myanmar and the design results could provide reference cases for drilling activities in this deep water gas field.