防气窜固井分段设计方法

摘要

To guide anti-gas channeling cementing design ,and avoid circulation loss or underbalanced gas channeling ,sectional design method for anti-gas channeling cementing was developed .Since the slurry temperature in annulus varies with depth ,the build-up of gel strength and pressure drop are different at dif-ferent depths ,the hydraulic pressure loss of slurry column is calculated in sections .By adjusting slurry per-formance and setting the grow th of gel strength to be linear from top to bottom of slurry column ,and mak-ing gel strength of tail slurry up to 240 Pa ,the average gel strength of lead slurry is less than 48 Pa .An ac-curate calculation model of hydraulic pressure loss of slurry was established ,and sectional design and bal-anced cementing methods were developed .The methods have been used to cementing design in more than 200 gas wells in northeastern Sichuan province ,the success rate of anti-gas channeling has been 100% .The method provides an effective calculation model for anti-gas channeling cementing design .%为指导防气窜固井压稳设计，避免过压稳或欠压稳，研究了防气窜固井分段设计方法。基于环空水泥浆液柱中不同深度的水泥浆因温度不同导致静胶凝强度增长速度不同，以及不同深度的压力损失也不同的实际情况，对环空水泥浆的液柱压力损失进行分段计算。设定水泥浆液柱静胶凝强度的增长自上而下是线性增长，通过调整水泥浆性能控制分段水泥浆静胶凝强度的发展，使尾浆静胶凝强度达到240 Pa时，领浆平均静胶凝强度小于48 Pa ，建立了水泥浆液柱压力损失精确计算模型，提出了分段设计方法和压稳判定方法。在川东北地区100多口气井固井施工设计中应用该方法，固井防气窜成功率达到100％。该方法为防气窜固井环空设计提供了理论计算模型。