井下节流技术是利用井下节流器防止水合物生成的采气工艺技术。目前,超高压气井多采用地面井口加热、多级节流的集输工艺,存在地面节流工艺流程复杂、人员操作不便等问题,现有的井下节流器最大节流压差70 MPa,限制了超高压气井的应用。针对上述问题,提出井下+地面双级节流和井下双级节流两种方案。以川渝地区某超高压气井为例,通过建立模型,进行双级节流方案的可行性论证,研究表明:1)采用井下+地面双级节流,低配产时,地面节流后温度低于地面水合物生成温度,地面还需配备水套炉，高配产时,地面节流后温度高于地面水合物生成温度,地面不需要额外配备水套炉；2)井下安装两个节流油嘴,计算节流后温度高于水合物生成温度,确保不会生成水合物,井下双级节流方案可行；3)通过合理设计,井下两个节流油嘴尺寸的差异不会导致其中一个节流油嘴失效,可以达到井下双级节流的目的。研究成果可为超高压气井井下节流技术的现场应用提供依据。

Downhole throttling technology is a gas production technology that uses downhole throttler to prevent hydrate formation. At present, surface wellhead heating and multi-stage throttling gathering and transportation technology are widely accepted in ultra-high pressure gas wells. Yet, there are such issues as complex surface throttling process and inconvenient operation by personnel. The maximum throttle pressure difference of the existing downhole throttler is 70 MPa, which limits the application of ultra-high pressure gas wells. To address the above problems, two schemes of Underground Plus Ground Two-Stage Throttling and Two-Stage Underground Throttling are proposed. Taking an ultra-high pressure gas well in Sichuan-Chongqing area as a case, the feasibility of two-state throttling scheme is demonstrated by modeling. The results show that: (1) With Underground Plus Ground Two-Stage Throttling, when the production is low, the temperature after ground throttling is lower than the surface hydrate formation temperature, and a heating device is required. At high production rates, the temperature after ground throttling is higher than the surface hydrate formation temperature, and no extra heating devices is required. (2) When two throttling nozzles are installed downhole, the calculated temperature after throttling is higher than the hydrate formation temperature to ensure that no hydrate is generated in the wellborn. Therefore, the downhole two-stage throttling is feasible. (3) With optimum design, the sizing difference of two downhole throttling nozzles will not lead to the failure of another throttling nozzle. So, the target of downhole two-stage throttling can be well met. The research results can provide basis for field application of downhole throttling technology in ultra-high pressure gas wells.