致密含水气藏气井提高配产对开发效果影响研究

Study on the influence of gas wells in tight water-bearing gas reservoir on the development effect of increasing production

致密含水气藏具有低压、低孔、低渗、非均质性强、含气饱和度低以及孔喉细小等储层特征。为了研究提高配产对致密含水气藏气井开发效果的影响,对比分析了提高配产前后不同提高配产比例和不同液气比气井的压力、单井最终可采储量(EUR)及阶段累产气等开发参数。研究结果表明:1)提高配产比例及气井液气比越大,气井EUR下降幅度也越大;当气井提高配产比例大于50%或液气比大于5 m^(3)/(×10^(4) m ^(3))时,EUR下降比例可达40%。2)致密含水储层应力敏感程度增幅7%~12%,且含水饱和度越高,应力敏感程度越强,渗透率急剧降低。3)生产压差增大,参与流动的地层水增多,近井地带更易积液且积液范围将扩展至地层中部,造成采收率大幅下降。4)井筒内液滴回落,流体侵入储层容易引起近井地带水锁,造成气相渗流能力大幅下降。该研究成果对同类型含水气藏科学合理开发有指导意义。

Tight water-bearing gas reservoirs have the characteristics of low pressure,low porosity,low permeability,strong heterogeneity,low gas saturation and small pore roar.In order to study the effect of increasing production allocation on the development effect of gas wells in tight water-bearing gas reservoirs,comparative analysis of development parameters such as pressure,final recoverable reserves of a single well(EUR),and stage cumulative gas production of gas wells with different production ratios and different liquid-gas ratios before and after increasing production allocation.The result of research shows that:1)The greater the proportion of high production allocation,the greater the decline in EUR of gas wells;When the gas well increase the production ratio by more than 50%or the liquid-gas ratio is more than 5 m^(3)/(×10^(4) m^(3)),the EUR reduction ratio can reach 40%.2)The stress sensitivity of tight water-bearing reservoirs increased by 7%~12%,and the higher the water saturation,the stronger the stress sensitivity and the sharp decrease in permeability.3)The production pressure difference increases,the formation water participating in the flow increases,and the near-wellbore area is more likely to accumulate liquid and the range of the liquid accumulation will extend to the middle of the formation,resulting in a substantial decrease in the recovery factor.4)The droplets in the wellbore fall back,and the fluid intrusion into the reservoir can easily cause water lock in the near-wellbore zone,resulting in a significant decrease in the gas seepage capacity.The research results have guiding significance for the scientific and rational development of the same type of water-bearing gas reservoirs.