针对盐膏层的钻井液体系室内研究与评价

针对在盐膏层钻进时经常出现严重的井壁失稳的问题,通过大量室内试验研究得出了一套适用于盐膏层的钻井液体系。该体系是由筛选出的抗盐、抗钙、抑制性性能很好的有机处理剂组成,辅以无机盐抑制剂(氯化钾、硅酸钠),利用其协同作用和化学反应作用来提高体系整体对盐、膏溶解及粘土分散膨胀的抑制性。试验证明,该体系具有良好的流变性和失水造壁性,能有效抑制盐、石膏的溶解和泥页岩分散、膨胀,并且有很强的抗盐侵、抗膏侵、抗钻屑污染能力,可以使体系在钻遇盐膏层时保持其稳定性能,而安全钻过该段。

Experimental Study and Evaluation on Drilling Fluid System for Drilling the Evaporate(Salt-gypsum) Beds

In allusion to the problems of unsteady wellbore in drilling the evaporate(salt-gypsum) beds,a set of drilling fluid systems suitable for the evaporate bed drilling were obtained by using great number of experimental studies.The system had a good performance of salt resistance,calcium resistance and inhibition,which was supported with inorganic salt inhibitors(potassium chloride and sodium silicate),its co-action and chemical reaction were used to improve the inhibition to the salt,gypsum solution and clay dispersion and expansion.The experiment shows that the system has a good rheology and wall-cake-building character,by which salt,gypsum solution and shale expansion and dispersion can be effectively controlled,it also has the ability of anti-salt invasion,anti-gypsum invasion,and anti drill-cuttings invasion and it is stable in drilling salt-gypsum bed.