伊拉克哈法亚油田高压盐膏层安全钻井技术

盐膏层钻井是当前钻井技术的难题之一，钻井施工中存在盐膏层及软泥岩层安全钻进难度大、井身质量控制困难和卡钻几率较大等问题。本文针对伊拉克哈法亚油田的地层条件：改变了盐膏层段套管坐封点，使套管漏封漏失状况得到有效控制；将定向轨迹井斜角由71.29°优化为29.48°，避开了易形成岩屑床井段，有效控制定向段卡钻，提高施工效率23%；确定哈法亚油田软泥岩缩径周期为48 h左右。根据缩径规律开展钻井，有效减少了钻头泥包和泥环的形成。确定了依据石膏岩、盐岩含量变化控制饱和盐水钻井液密度的原则，形成了控制饱和盐水钻井液黏度的现场维护技术措施。

Safe Drilling Technology of High Pressure Salt Paste Formation in Halfaya Oilfield,Iraq

Drilling of salt paste layers is one of the problems of current drilling technology. During the drilling construction, there are problems such as the difficulty in safe drilling of salt paste and soft mudstone layers, control of well quality, and high probability of stuck drilling, etc. Based on the formation conditions of Halfaya oilfield in Iraq, the authors changed the casing sealing point of salt-gypsum interval,effectively controlled the casing leakage,and optimized the angle of directional trajectory well from 71.29° to 29.48°, thus avoided the well sections that are easy to form rock chip beds and the well stuck in the directional sections, hereby the drilling efficiency was improved by 23%. The shrinkage period of soft mudstone in Halfaya oilfield is determined to be 48 h approximately. Drilling according to the diameter reduction law effectively reduced the formation of mud packs at the bit and mud rings. Through this study,the principle of controlling the density of saturated brine drilling fluid according to the content change of gypsum rock and salt rock is determined, and the on-site maintenance technical measure for viscosity control of saturated saline drilling fluid is formed.