长庆苏25断块低压易漏失气井固井技术

针对长庆地区苏25断块地层易塌、易漏、大量出水、目的层低压异常、漏失严重等复杂情况，采用正注反挤的固井方法与适宜的水泥浆技术（分段封固、梯度凝结），防漏失、防失重，压稳气层；在有效减少井底液柱压力防漏的基础上，使用不同堵漏材料，复合堵漏，防漏与堵漏结合，彻底控制住漏失；在调整水泥浆密度、抑制地层出水的基础上，改善水泥石内部结构，增加地层出水阻力，防洛河水腐蚀。经过数口气井的固井实践，该技术得到不断完善提高，积累了一些有益经验。

Cementing Technology for Low-pressure Lost Circulation Zones in Block Su-25 in Changqing

The Block Su-25 in Changqing Oilfield has heaving formations into which mud losses frequently take place and from which water production is high.The reservoirs have abnormal low pressures.Positive injection-reverse squeezing technology was used in well cementing,combined with block squeeze and gradient solidification technologies.Effort was made to avoid weight loss of the cement slurries and gas-bearing zones were completely controlled.Cement slurry losses into the formations are completely eliminated by minimizing the fluid column pressure in the well and using complex lost circulation materials with different size distributions.The densities of the cement slurries were carefully engineered and formation water rigorously controlled,while improving the internal structure of the set cement to increase the resistence to water production.The cement technology,which has been applied on several wells,is improved by field practices.