复合盐防腐钻井液的研制与现场应用

DEVELOPMENT AND FIELD APPLICATION OF COMPOUND SALT DRILLING FLUID FOR CORROSION CONTROL

潜江凹陷地下含有近千米厚的盐、膏及芒硝层，钻井时用饱和复合盐钻井液体系，以便与地下盐开层等配伍。由于饱和复合盐钻井液中合大量的Cl^-、Ca^(2+)、SO^(2-)以及添加的成分复杂的多种处理剂，并由于高温产生溶解氧，使钻具腐蚀相当严重。按APIPR131、APIPR13B标准配制防腐钻井液体系，研制的增粘剂及部分降先水剂具有较明显的抗蚀性，应用时作为防腐钻井液的首选添加剂，经试验pH伍控制在8～10为最好。并根据腐蚀特征，研制了一种复配性援蚀剂──DFP，通过4口井（120C，3000m）的现场试验，防腐效果明显，缓蚀率达80％以上。钻具从井内起出表面光亮，在钻台上停放12d不生锈，较好地解决了江汉油田复合盐钻井液对钻具的腐蚀问题，具有较明显的经济效益和社会效益。

For Jianghan oil field in Qianjiang sag, which contains about one thousand meters of salt, gypsum and mirabilite underground, a saturated compound salt drilling fluid system was used to be compatible with underground salt/gypsum formation. The great amount of Cl-,Ca'+,SO:- and various additives with complicated composition in the saturat-ed compound salt drilling fluid as well as the dissoved oxygen generated under high tempera-ture c3used serious corrosion of drilling tools. The anticorrosion drilling fluid system devel-oped per API PRB1 and API PRl3B, viscosity intensifier and partial filtrate reducer have re-markable anticorrosion property. They are the priority additives for drilling fluid and the test showed that their pH value is controlled at 8~10 preferentially- A compoundable DFP corro-sion inhibitor has been developed based on corrosion feature. 4 well (120°, 3000m)pilot exhib-ited good anticorrosion result with inhibition rate greater than 80°. The drilling tools pulled out from wellbore had smooth and bright surface and no rust occurred during 12 day stay on drilling floor. It has solved the corrosion problem of drilling tools caused by compound salt drilling fluid and has remarkable economic and social effects.