油基钻井液堵漏用吸油黏滞聚合物研制及应用OA北大核心

Lost circulation materials(LCMs),after being wetted by oil-based drilling fluids,have their sliding ability decreased and retention ability increased,causing them to be easy to flow back from the fractures through which the mud is lost and circulation is lost again.Using these LCMs,the success rates of lost circulation control are low.To improve the retention ability of the LCMs and the stability of the plugging layers,an oil absorbing viscous polymer MBS was developed.MBS is mainly composed of butadiene-styrene block copolymer BS and is formed by the coupling and grafting of inorganic minerals at a temperature between 70℃and 90℃.The rate at which MBS absorbs oil and becomes viscous is controllable.At room temperature,the oil-absorbing rate of the polymer MBS is relatively low,and the viscosity of the LCM slurry is small,making the slurry preparation and pumping very convenient.At the temperature of a lost circulation zone,the oil-absorbing rate of the polymer MBS increases,and the viscosity of the LCM slurry becomes higher,making it convenient for the LCM slurry to be retained inside the fractures through which the mud is lost.Moreover,the inorganic minerals enhance their supporting effects on the LCM slurry.MBS can absorb oils that are 2.94 times of its volume.At a concentration of 5%,the viscosity of the LCM slurry increases,and the fluidity decreases by nearly 50%.When the concentration of MBS is 10%,it can be effectively retained in a smooth fracture with a width of 2 mm,and the pressures bearing capacities in the forward and reverse directions are 0.69 MPa and 0.53 MPa respectively.An LCMs slurry formulated with MBS and other commonly used LCMs was used in the well section of 2,900-3,130 m of the well Puluye XHF.The LCMs slurry effectively stabilized the pressure at 4.2 MPa,achieving the goal of controlling lost circulation and increasing the pressure bearing capacity of the formations.The lost circulation was controlled successfully in the first try.