元坝高含硫气井环空起压诊断评价方法及应用

METHOD TO EVALUATE THE ANNULUS PRESSURE INCREASE IN H_2S GAS WELLS AT YUANBA AND ITS APPLICATION

气井生产过程中,环空带压现象逐渐增多,特别是含硫化氢气井,已成为影响安全生产的潜在风险,文章针对元坝高舍硫气井特点,参照API.RP90及B-Btest,提出了开井初期环空起压快速诊断流程及放压漏点判断流程,建立了套压增量预测图版,提出了在50~70×10~4 m^3/d的产量下,环空压力上涨在15~20 MPa的规律;并对API.RP90计算最大环空允许压力方法进行了修正,建立了多因素影响下的最大环空允许压力计算方法及五步环空日常维护管理方法,现场应用验证了该方法可确保高含硫气井的长期安全生产。

During gas well production,annulus pressure phenomenon gradually increased,especially in gas wells containing hydrogen sulfide,which had become a potential hazard.In this paper,according to the characteristics of high H_2S gas wells at Yuanba,with reference to API.RP90 and B- Btest,quick diagnosis process for annulus pressure increase upon the well opening and the diagnosis process for leakage point during pressure bleedoff were established,and the casing pressure increment prediction chart was made.It was concluded that the annulus pressure increased 15 ~ 20 MPa when production rate 500 000 ~ 700 000 m^3/ day.And the method calculating the maximum allowable annulus pressure described in API RP90 was modified,a new method considering variable affecting factors was set up,and a five-step daily annulus maintenance and management method was proposed.The Held application shows that this method can ensure a long-time safe production in high H_2S gas wells.