High temperature and high density drilling fluid is always a difficult problem in drilling fluid field.Since the construction of West II H4-1 in Shengli Oilfield, there has been no great breakthrough in the technical limitation. When the well depth exceeds 7,000 m and the well temperature exceeds 180℃, the high temperature and high density drilling fluid is faced with such problems as large performance fluctuation, unstable temperature resistance and difficult maintenance.
MECO oxidized asphalt solves the prominent problem of rheology and suspension stability control of drilling fluid under high temperature and high pressure conditions. Compared with conventional drilling fluid, the drilling fluid system with MECO oxidized asphalt has three advantages: more stable rheology, better wetting and better plugging and collapse prevention effect.
The results are good in the field application of West II H4-1.The drilling depth of the West II H4-1 well is 6941m, the maximum working density is 2.34g/cm3, the bottom hole temperature is 180℃, and the mud viscosity has been maintained at 40-50s. The drilling fluid which using MECO oxidized asphalt has good performance and stable borehole wall without any settling phenomenon, which solves the problem of oil base cuttings treatment in shale drilling construction.
The drilling fluid system with MECO oxidized asphalt overcomes the problem of large friction resistance and torque of the conventional drilling fluid, and reduces the friction and rotary torque in the process of tripping and significantly improves the drilling speed.
It can also solve the problem that traditional drilling fluid system is not resistant to high temperature.
It laid the foundation for the high quality and efficient completion of this well.
Drilling fluid maintenance costs were also reduced by 10%, which providing a strong guarantee for late deep well construction, saving drilling cycles and drilling investments.
