隐形酸完井液的性能研究

Study on the Completion Fluid Containing Chelating Acid

隐形酸完井液是在传统的碱性完井液基础上发展而来的。研究了隐形酸完井液的腐蚀性和缓蚀效果。从溶蚀率和pH值的变化关系,可确定隐形酸螯合剂的适宜加量为0.8%～1.0%,此时溶液pH值为1.72～1.61,对N80钢片的腐蚀速率约为5.978～7.003mm/a,因此需要添加缓蚀剂。当用HCOONa作密度调节剂时,加入2%JCE缓蚀剂,N80钢片的腐蚀速率从7.003降至0.089mm/a;当用KCl作密度调节剂时,由于有活性离子Cl–存在,比用HCOONa作密度调节剂时缓蚀控制难度加大,缓蚀剂加量从2%提到3%,N80钢片的腐蚀速率可降至0.067mm/a。该隐形酸完井液中各种添加剂的配伍性好,浊度值在10NTU以内,远小于施工要求的30NTU,不对储层造成伤害。

In a study on the corrosion of completion fluid containing chelating acids,the appropriate concentration of the chelating acid is 0.8%～1.0% according to the relationship between corrosion rate and pH. At this concentration range the pH of the solution is between 1.72 and 1.61,and the corrosion rate on an N80 steel is in a range of 5.978～7.003 mm/a. This corrosion rate dictates the use of corrosion inhibitor. Compared with HCOONa,a completion fluid weighted with KCl has stronger corrosion because of the presence of Cl–,hence the concentration of corrosion inhibitor is increased from 2% to 3%,and the corrosion rate of the N80 steel plate is reduced to 0.067 mm/a. Additives used in this completion fluid have satisfactory compatibility,and the turbidity of the fluid is less than 10 NTU,much smaller than the technical requirement,30 NTU.