Application of high-performance water-based drilling fluids for horizontal wells in tight reservoir of Daqing oilfield

The tight reservoirs of Gaotaizi reservoir and Fuyu reservoir of Quantou formation of Qingshankou formation in the periphery of Daqing placanticline have poor physical properties and thin single layer thickness. A series of problems exist in the construction, such as high formation friction, low penetration rate, long drilling cycle and wellbore instability. Higher requirements are put forward for the inhibition and lifting capacity of drilling fluid. Considering the cost, environmental protection and other factors, the oil-based drilling fluid has been unable to meet the current requirements of large-scale benefit development of tight reservoir. In order to meet the development needs of horizontal wells in the middle and deep tight reservoirs in Songliao basin, a high-performance water-based drilling fluid system was developed. Amine inhibitor AP-1 and polyol were introduced into the cationic polymer drilling fluid system to improve the inhibition of drilling fluid. The "turbid-point effect" of polyol is used to block the micro-fracture of shale formation, which improves the wellbore stability of shale formation. The results show that the system is characterized by strong inhibition, good lubricity, low filtration loss and etc., and can effectively solve a series of problems in the construction of tight oil horizontal wells around Daqing placanticline.