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在海底含天然气水合物地层钻进时,水合物的分解和进入泥浆循环系统的天然气重新生成水合物是影响钻井安全的主要因素.为获得确保在水合物地层安全钻进的钻井液,利用“天然气水合物模拟实验系统”研究评价:粘土对甲酸盐钻井液低温流变性的影响、甲酸盐无土钻井液的低温流变性和动力学抑制剂PVPK-30、PVPK-90的水合物抑制效果.表明:加入粘土的甲酸盐钻井液在低温条件下粘、切增长较快;甲酸盐无土钻井液在低温条件下,流变参数变化不大;在-4℃和18MPa附近压力的实验条件下,PVPK-90抑制性能优于PVPK-30;加入1%PVPK-90的甲酸盐无土钻井液抑制效果良好.
Hydrate decomposition and rehydration of natural gas into the mud circulation system is a major factor affecting drilling safety while drilling on the seafloor containing gas hydrate.To obtain a drilling fluid that ensures safe drilling in the hydrate formation, “Gas hydrate simulation experimental system” research evaluation: clay formate drilling fluid low temperature rheological properties, low temperature rheology of formate brine and drilling fluid kinetic inhibitors PVPK-30, PVPK-90 hydration The results showed that the viscosity of the formate drilling fluid added into clay increased rapidly at low temperature and the rheological parameters of the formate drilling fluid did not change much at low temperature. Under the experimental conditions of near pressure, the inhibition performance of PVPK-90 is better than that of PVPK-30; and the inhibition effect of 1% PVPK-90 in soilless drilling fluid is good.