华北油田杨税务潜山内固井技术

华北油田为开发冀中坳陷廊固凹陷杨税务潜山内油气藏，先期部署了3口重点探井。该区块潜山内地质条件复杂，地层压力系数为0.94~1.09，存在多套活跃油、气层且埋藏深，容易发生漏失；地温梯度高、小井眼小间隙、尾管封固段长、对水泥环完整性要求高。综合分析以上因素，杨税务潜山内ϕ127 mm尾管固井风险较大，固井施工安全和固井质量难以保证。针对以上固井难点，主要从以下几方面进行研究。①优化井眼清洁技术，采用旋流短节扶正器，保证了套管安全下入。②用软件模拟顶替效率和关键点压力变化，合理调整施工参数，保障固井施工实现"三压稳"。③采用韧性水泥浆及冲洗隔离液体系，合理设计施工参数，确保水泥浆性能稳定，水泥石韧性满足体积压裂要求。通过3口井的现场应用表明，使用该技术后，固井质量明显提高，为华北油田杨税务潜山内固井提供了技术保障。 

Cementing Technology for Buried Hill Reservoirs in Block Yangshuiwu in Huabei Oilfield

Three key exploratory wells have been deployed in Huabei Oilfield to develop the buried hill reservoirs in Block Yangshuiwu in Langgu sag of Jizhong depression. The geologic conditions in the buried hill are complex. The formation pressure coefficient is 0.94-1.09. There exist multiple deep active oil and gas zones. Lost circulation has occurred frequently in this area. High geothermal gradient, slim hole, narrow annular clearance, long section of liner string to be cemented and rigorous requirements on the integrity of cement sheath. It is understood from these facts that cementing of the 127 mm liner string is highly risky, and operation safety and job quality of well cementing are difficult to guarantee. Efforts have made to deal with these difficulties:1) optimizing technology for borehole cleaning, using cyclone sub centralizer to ensure the success of casing running. 2) using computer software to simulate displacing efficiency and pressure changes at critical spots. Appropriately adjust operation parameters to ensure pressure control. 3) using tough cement slurry and flushing spacer system, designing appropriate operational parameters, ensuring the stability of cement slurry and the toughness of set cement that satisfies the requirements for SRV fracturing. Field operations on three wells show that the application of cementing technology remarkably improved the job quality of well cementing, providing technical support for well cementing in the buried hill in the Block Yangshuiwu in Huabei Oilfield.