Experimental Study on High Performance Polyamine Drilling Fluid for Deepwater Drilling

High performance polyamine drilling fluid,a water-based drilling fluid,is similar to oil-based drilling fluid in performance,and has broad application prospects in the deepwater drilling.In order to break the technical monopoly of foreign companies and reduce costs,based on the development of a highly inhibitive polyamine shale inhibitor and taking consideration of low temperature rheology and hydrate inhibition,a high performance polyamine drilling fluid had been formed for deepwater drilling by selecting additives.The comprehensive evaluation results showed that the property of the drilling fluid is stable after hot rolling at 150 ℃.The ratios of apparent viscosity and yield point at 2 ℃ and 25 ℃ were 1.36 and 1.14 respectively,which indicated that the drilling fluid was good in low temperature rheological property,and comparable with oil-based drilling fluid in shale inhibition,suggesting the drilling fluid is highly inhibitive.In a simulating condition of low temperature and high pressure (1.7 ℃,17.41 MPa) at 1 500 m water depth,there would be no gas hydrate formed in the drilling fluid in 120 hours.Moreover,it had good resistance to CaCl2(up to 1.0%) and cuttings (up to 8.0%) contamination.The EC50 value of the drilling fluid was higher than 11 000 mg/L,the drilling fluid could meet the environmental requirements of deepwater drilling without any biological toxicity.The primary performance indexes are largely to remain the same with that of polyamine drilling fluids used in overseas deepwater drilling operations,and can meet the requirement of deepwater drilling.