川西深层、超深层气井排水采气技术初探

Preliminary Study on Drainage and Gas Production Technology for Deep and Ultra-deep Gas Wells in Northwest Sichuan

川西北部投产的海相深层气井产层中深普遍超过6000 m,具有温度高、压力高、硫化氢含量高、完井管柱复杂和气水关系复杂、水量范围大的特点,目前排水采气工艺举升深度主要在6000 m以内的气井,6000 m以上气井排水采气尚无应用先例。针对深层、超深层气井特征,通过统计对比研究,初步形成了适应该类气井的排水采气措施:一是针对气井排水采气难点及需求、结合技术应用现状,优选出适合该类气井的排水采气主体技术;二是开展气举工艺可行性论证,结论表明气举能够适应川西海相深层气井生产初期的排水需求,但工艺所需最低地层压力较高,后期需进行工艺接替;三是根据阶段生产特征,制定了“初期降井口压力、中后期降井底流压”的阶段排水采气方案;四是提出超深井排水采气攻关方向及后续接替工艺措施,延长工艺有效期。川西深层、超深层气井排水采气技术的研究和探讨对该类气井稳定生产具有现实指导意义。

The central vertical depth of the deep marine gas wells in northwest Sichuan is generally over 6000 m,which is characterized by high temperature,high pressure,high hydrogen sulfide content,complex completion string,complex gas-water relationship and large range of water production.At present,the drainage gas production technology is mainly applied in gas wells within 6000 m,but there is no precedent for gas production in wells above 6000 m.For deep and ultra-deep gas well characteristics,through statistical comparative studies,the measures of water drainage and gas production have been preliminarily formed for this kind of gas wells:first,according to the difficulty and demand of drainage and gas production in gas well,combined with the application status,the main drainage and gas production technology suitable for this type of gas well is optimized;second,through the feasibility demonstration of gas lift technology,the conclusion shows that the gas lift technology can meet the initial drainage demand of deep gas wells,but the minimum formation pressure required by the technology is high,and the technology replacement needs to be carried out in the later stage;third,according to the characteristics of stage production,the stage drainage gas production scheme of"reducing wellhead pressure at the early stage,reducing well flow pressure in middle and later stages"is established;fourth,the paper puts forward the direction of gas production in ultra-deep well and the following measures to extend the period of validity of the technology.The research and discussion of deep and ultra-deep gas wells drainage and gas production technology in northwest Sichuan has practical guiding significance for such gas wells.