成膜封堵低侵入保护油层钻井液技术的研讨

为使钻井过程所采用的钻井液对所钻遇的不同渗透率油层均能有效地阻止其固相与液相进入油气层,不诱发储层的潜在损害因素,防止对储层发生损害,提出了成膜封堵低侵入保护油气层钻井液技术的新构思.其核心是在钻开油气层钻井液中加入成膜剂、特种封堵剂和降滤失剂.在钻开油气层的极短时间内,此钻井液中的膨润土、加重剂、岩屑等固相在不同渗透率的油层表面架桥、填充形成内外泥饼,特种封堵剂和高温高压降滤失剂封堵近井壁油层内外泥饼的孔喉,成膜剂在井壁上成膜,封堵孔喉未被架桥粒子、填充粒子、降滤失剂封堵的空间,从而形成钻井液动滤失速率为零、厚度小于1 cm的成膜封堵环带,有效阻止钻井液固相和液相进入油气层.此项技术对钻遇的不同渗透率油层均能有效减少损害,通过室内实验证实了其可行性.

Study of the Film Forming&Sealing & Low Invasion Reservoir Protection Drilling Fluid Technology

To prevent solids and filtrates of drilling fluid into different reservoirs effectively and prevent formation damage,the film forming,sealing,low invasion and reservoir protection drilling fluid was developed in which the film forming agent,special sealing agent and fluid loss control agent are essential to this fluid.As soon as getting into the reservoir,the solids such as clay,weighted materials and cuttings can instantly bridge and pack on the face of sands thus forming the internal and external mudcakes.The special sealing agent and the HTHP fluid loss control agent are employed to seal the pores and throats of mudcakes near wellbore.The film forming agent is used to seal the rest spaces by forming the film on the wall of hole.Thus,the dynamic filtration rate of the fluid can be reduced to zero and the thickness of shielding ring is smaller than 1cm.The solids and filtrates can be prevented into the reservoir effectively.This drilling fluid technology can be available to a wide range of permeability and its feasibility was verified by laboratory experiments.