黄河三角洲区域地面沉降监测钻孔施工实践

Construction practice of ground subsidence monitoring drilling in the Yellow River Delta

摘要:

黄河三角洲属海陆交互作用下陆架沉积过程典型区域，砂层、泥岩居多，地层胶结性差且泥、砂互层频繁。在地面沉降监测钻孔施工中，存在泥岩地层造浆、砂层涌水、漏失、冲洗液被稀释、超径、孔壁坍塌风险等技术问题，同时要求保持岩心原状性。针对技术难题，采用了跨口径绳索取心钻具、钾基低固相聚合物冲洗液体系、水压出心等关键技术方法，同时做好冲洗液固相控制、短起钻工作。水泥封孔，为了保证封孔效果和封孔作业安全，使用了油井水泥和减水剂，在不改变水灰比的情况下，显著增加水泥浆的流动性，降低封孔事故概率。该钻孔的顺利完成，为今后滨海区域沉积地层类似岩心钻探提供借鉴。

Abstract:

The Yellow River Delta is a typical area of continental shelf sedimentation under the interaction of land and sea， with a majority of sand and mudstone layers， poor stratigraphic cementation， and frequent interbedding of mud and sand. In the drilling construction for ground subsidence monitoring， technical problems such as mud making in mudstone formations， water inflow in sand layers， leakage， dilution of mud， over diameter， and risk of hole wall collapse often occur. At the same time， the original state of the rock core should be maintained. In response to the technical difficulties， key technical methods such as cross caliber wireline core drilling tools， potassium based low solid polymer flushing fluid system， and water pressure coring were adopted， while also ensuring solid phase control and short lifting. Cement sealing is used to ensure the sealing effect and safety of the sealing operation. Oil well cementing and water reducing agent are used to significantly increase the fluidity of the cement slurry and reduce the probability of sealing accidents without changing the water cement ratio. The successful completion of this drilling provides a reference for similar core drilling in sedimentary formations in coastal areas in the future.