High inhibition and anti-sloughing water-based drilling fluid technology for horizontal wells in tight oil reservoirs in Daqing Oilfield

In view of the problems like wellbore collapse or sticking. during drilling of horizontal wells in tight oil reservoirs in Qijia Block of Daqing Oilfield, a high inhibition and anti-sloughing water-based drilling fluid was developed based on polysulfonate water-based drilling fluid system. Lab research shows that co-suppression of polyalcohol and organic silicat can effectively reduce the water sensitivity of mudstone and mud shale. Using polyaluminum plugging agent to seal the micro-fissures in the formation can also improve the wellbore stability capacity. This system was used in five wells in Qijia Block, and no accidents like wellbore collapse and lost circulation occurred. The average ROP was 14.5 m/h, the average hole size enlargement was 5% and the friction drag during drilling of horizontal section was 30kN to 60 kN. So this technology effectively addressed the problems in the drilling of horizontal well with long horizontal interval in tight oil reservoirs of Qijia Block of Daqing Oilfield, and provided reference for effective drilling in tight oil reservoirs.