长庆神木区块天然气井一次上返固井技术

One-time up-return cementing technology for natural gas wells in Shenmu block of Changqing Oilfield

长庆油田神木区块天然气井固井难度大,上部刘家沟组承压能力低,下部含气层跨度大,气层活跃,完井改造过程中井筒内压力高。为提高套管串承压能力及密封性,该区块改分级固井为一次上返固井工艺。为解决该区块一次上返固井难题,研发了以GGQ复合减轻材料为主的低密度水泥浆体系封固上部低压易漏层,泡沫防窜水泥浆体系封固下部气层活跃地层。实验表明低密度水泥浆体系受压后密度变化值小,且具有一定的防漏堵漏功能;泡沫防窜水泥浆体系能够有效防止气窜产生。现场应用结果表明,该套体系能够解决神木区块一次上返固井难题,提高该区块固井质量。

The cementing technology is difficultly used to natural gas wells in Shenmu area of Changqing Oilfiled. The upper stratum is Liujiagou group with low pressure - bearing ability, and the under nature gas - bearing stratum with a long stretch is active, with high pressure in the wellhole in the process of well completion. To improve the pressure - bearing a- bility and tightness of the casing string,the staged cementing was changed to one - time up - return cementing in this area. In order to solve the problem of the one - time up - return cementing, we researched a low density cement slurry system based on GGQ for upper stratum with low pressure -bearing ability and anti -channeling cement slurry system with foam for the under active nature gas - bearing stratum. Experimental results showed that the density change values of low density cement slurry system is small after compression, and has function of leak - proof plugging ; the foamed anti - channeling cement slurry system can effectively prevent gas - channeling. Field application results showed that the system can solve problems of up - return cementing in Shenmu area, and improve the cementing quality of the area.