深井盐膏及盐水地层固井隔离液体系研究

LABORATORY STUDY ON CEMENTING SPACER-FLUID SYSTEM FOR DEEP-WELL IN SALT-GYPSUM BED AND BRINE WATER LAYERS

目前国内深井多钻遇盐膏和盐水地层,常用隔离液体系抗温和抗盐能力较差,温度超过100℃时,在低浓度盐作用下体系失稳沉降严重,易造成固井施工复杂,注替安全隐患极大。选用一种多糖聚合物作为高温抗盐悬浮稳定剂,辅以耐盐的降失水剂及流型调节剂,研制了一套高温抗盐隔离液体系。该体系在钠盐、钙盐和镁盐溶液中均能保持稳定的性能;使用温度可达140℃;具有较好的密度调控能力,在1.3～2.4g/cm3可调;且与常规钻井液、水泥浆具有较好的相容性。该套体系有望应用在深井超深井及盐膏地层、复合盐岩层和盐水地层固井注水泥作业中。

Recently salt-gypsum beds and brine water layers are frequently encountered when drilling deep wells.The conventional spacer system has a relatively poor salt and temperature tolerance.When the temperature exceeds 100 ℃,the system loses its stability in the low concentration of saline water and can cause serious cementing accidents and has a great potential safety hazard of injection and displacement of slurry.A polysaccharide polymer is chosen as high-temperature and anti-salt suspension stabilizer,and supplemented by salt-tolerant fluid loss additive and pattern adjusting agent,a high-temperature and anti-salt spacer system is developed.The system could maintain its stability in the sodium,calcium and magnesium salt solution.It can be used in a temperature of 140 ℃ and has a preferable regulation ability of density which can be adjusted between 1.3 and 2.4 g/cm3.It also has a good compatibility with conventional drilling fluid and cement slurry.The system is expected to be used in cementing job of the deep-well,high-deep well,and salt-gypsum bed,composite rock salt layer,and brine water layer.