小压差大温降工艺在榆林气田的应用

PROCESS APPLICATION OF GENERATING BIG TEMPERATURE DROP VIA SMALL PRESSURE DIFFERENCE IN YULIN GAS FIELD

直接节流膨胀制冷工艺是轻烃回收用低温分离方法中最常见的一种,要求天然气必须有较大的可利用压能和压差。为了在低压气田、气井上应用直接节流膨胀制冷工艺,首先采用动态模拟方法分析了小压差产生大温降的原理,采用节流阀小压差节流制冷、大面积换热预冷,换热与节流所形成的温差差距相互推动,最终能形成稳定的低温,从而获得大的温度降。小压差大温降工艺在长庆榆林气田上古生界气藏得到了应用并获得良好效果,为低压气田采用直接膨胀制冷工艺实施轻烃回收提供了现场试验依据。

Direct throttling expansion refrigeration is an ordinary low temperature separation method, which can be used to recover light hydrocarbon. This method requires available big pressure energy and pressure difference of natural gas. To apply this method in low-pressure gas fields and gas wells, dynamic simulation method was firstly adopted to analyze how to generate big temperature drop through small pressure difference. Meanwhile, small pressure difference throttling refrigeration and pre-cooling of extensive area heat exchange via throttle was performed. The differential temperatures which were respectively generated from heat exchange and throttling, can then be driven by each other to form stabilized low temperature. Accordingly, big temperature drop was acquired. The method was successfully applied in Neopaleozoic gas reservoir of Yulin gas field, Changqing, which provided on-site experimental statistics for direct throttling expansion refrigeration methods of low-pressure gas fields.