气体动力改造煤储层对井下套管柱安全性影响分析

Analysis on Influence of Gas Power Transformation CBM Reservoir on Safety of Underground Casing String

注入气体阶段与压力释放阶段是气体动力煤储层改造工艺对套管柱安全产生影响的2个关键阶段,为研究其影响程度,根据气体动力改造煤储层井的井身结构与套管柱,建立了气体动力煤储层改造井的套管、水泥环、围岩组合体力学模型,运用弹性力学理论对注入气体阶段、压力释放阶段套管的载荷进行了分析,并通过实例说明在注入气体阶段随着注入气体压力的变化,套管的外压载荷首先接近于挤毁压力,在压力释放阶段弹性应变能的瞬间释放会引起套管变形,在同等条件下,使用139.7 mm套管比177.8 mm套管安全。

The injected gas phase and pressure release stage are the two key stages in the process of CBM reservoir transformation which influences casing safety,to study this influences,according to well hole structure and casing string on well of gas power transformation coal reservoir, combination mechanics model of on casing string, cement loop and surrounding rock was established in well of gas power transformation coal reservoir. Load pressure release stage casing was analyzed by using the theory of elastic mechanics of the injected gas phase, and that in the injected gas stage with the change of gas injection pressure by example, the external pressure load of casing firstly closes to the collapse pressure,pressure release in the release phase of the elastic strain energy of the moment causes casing deforma- tion,under the same conditions,the usage of φ139.7 mm casing in diameter is better than φ177.8 mm casing in the safety of casing.