摘要
Abstract
Technical problems encountered in deepwater drilling, such as low temperature, narrow drilling window, formation of gas hydrate by shallow natural gas and hole sloughing etc. have posed rigorous requirements to drilling fluids. Using GTL Saraline 185V as the base fluid, a deepwater synthetic base drilling fluid, FLAT-PRO, was developed based on optimizing the emulsifier, organo-clay, filter loss reducer and other additives. Laboratory evaluation results showed that FLAT-PRO had stable constant rheology at 4-65 ℃. In permeability test, a permeability recovery of higher than 90% was obtained. This performed very well even when was contaminated with 10% seawater and 10% drilled cuttings. FLAT-PRO was easy to degrade, satisfying the need of environmental protection. An offshore well, LS-A, drilled in South China Sea, with water depth of 1,699.3 m, had formation (main target) temperatures between 34.6 ℃and 36 ℃. The coefficient of formation pressure at the shoe of the ?508 mm casing string was lower than 1.14, indicating a narrow safe drilling window. How to control ECD and mud losses were the major concerns of the drilling operation. FLAT-PRO with a density of 1.03 g/cm3 was used in spudding the well, and FSVIS was chosen to maintain the rheology of the drilling fluid. During drilling, rheological parameters of the drilling fluid were maintained as follows: FV = 50-70 s, YP = 8-15 Pa, φ6 reading = 7-15, andφ3 reading = 6-12. 2% of HFR was used in filtration control. Drilling, tripping and wireline logging were all successful performed. Filed application showed that the deepwater constant rheology FLAT-PRO drilling fluid had stable rheology at different temperatures, good inhibitive capacity, and superior lubricity, thereby maintaining low ECD during drilling and satisfying the needs for deepwater drilling.关键词
深水钻井/合成基钻井液/气制油/恒流变钻井液/钻井液配方/南海油田Key words
Deepwater drilling/Synthetic base drilling fluid/GTL/Constant rheology drilling fluid/Drilling fluid formulation/Nanhai oil field分类
能源科技
