苏里格气田井下节流参数优化

Optimization of Downhole Choke Parameters in Sulige Gas Field

井下节流工艺是苏里格气田低成本高效开采的关键技术。针对气井产水后井下节流油嘴是否利于携液这一生产技术难题,建立了带井下油嘴的产水气井压力、温度模型。在井下一级节流方面,对比分析了节流前后气液流速、持液率、液体体积流量、举升压降等参数,井下节流后气体流速增幅远大于液体流速,使液体持液率下降,但液体体积流量增大,即携带相同体积流量的液体所需的临界气量更小,证实了井下节流对携液有利。据此在卡瓦安全的前提下推荐井下一级油嘴位置为距产层顶部300~500m。在井下二级节流方面,从节流压降、温降入手对比分析了＂下小上大＂和＂下大上小＂两种二级节流技术方案,推荐采用＂下小上大＂和节流压降等分的设计方案,并根据温度恢复度来确定两个油嘴的间距,完善了井下二级节流技术方案。该研究成果将进一步完善井下节流携液的基础理论,为类似气井采用井下节流低成本高效开采提供了重要的技术支持。

Downhole choke process was the key technology of high efficient oil development with low cost in Sulige Gas Field.In allusion to the problem of whether or not the choke nozzle was favorable for fluid carrying after water was produced in gas wells,a model for predicting pressure and temperature was established for the water-produced gas wells,For a primary downhole throttling,the parameters of gas-liquid velocity,liquid holdup,liquid volume flow rate and pressure drop in oil production both before and after the choking were comparatively analyzed.The growth of gas velocity through the downhole choke was much higher than that of liquid flow rate,the liquid holdup dropped down,while its volume flow increased.That was the critical gas rate needed to carry the same liquid rate was lower,it was demonstrated that downhole choking was beneficial for fluid carrying.Therefore it was recommended that the downhole choke was installed 300-500 maway from the top of the reservoir.For the secondary throttling,2throttling schemes of choking techniques with choking nozzle diameters 'small in the lower section and big in the upper'and 'big in the lower section and small in the upper'were analyzed from the aspects of pressure drop and temperature difference,it was recommended that the technique with throttling nozzle diameters of'small in the lower section and big in the upper'should be used,the distance between 2nozzles should be determined based on the temperature restoration,therefore the secondary throttling scheme is perfected.The research result can be used to further complete downhole choking and fluid carrying theory and it provides a technical support for reducing production cost for high efficient gas development for similar gas wells.