基于气水相对渗透率曲线的产水气井开采效果评价——以苏里格气田致密砂岩气藏为例

如何定量评价不同产水量对气井开采效果的影响程度,一直是业内期待解决的问题。为此,依据气水两相渗流理论,在深入对比研究的基础上,提出了利用气水相对渗透率曲线定量评价产水气井开采效果的新方法,从而实现了对产水气井产能、产量、最终累计采气量和采收率的定量评价。进而以鄂尔多斯盆地苏里格气田致密强非均质性砂岩气藏为例,充分利用不同类型及不同产水程度气井实际生产动态资料,在进行大量计算的基础上,验证了该方法的实用性与可靠性,最终建立了苏里格气田产水气井在不同水气比条件下,气井产能、产量、最终累计采气量及采收率定量评价的经验公式和图版,为现场推广应用提供了技术支撑。研究结果表明:目前苏里格气田西区产水严重,水气比变化范围大,若平均水气比为1.0 m~3/10~4m~3,则气井产能、累计采气量及采收率的降低程度分别为24.4%、24.4%、17.4%;若气井水气比为2.0 m~3/10~4m~3,则气井产能、累计采气量及采收率的降低程度分别为40.2%、40.2%、33.2%。

Performance evaluation on water-producing gas wells based on gas-water relative permeability curves : A case study of tight sandstone gas reservoirs in the Sulige Gas Field,Ordos Basin

An outstanding issue in the oil and gas industry is how to evaluate quantitatively the influences of water production on production performance of gas wells. Based on gas-water flow theories, therefore, a new method was proposed in this paper to evaluate quantitatively the production performance of water-producing gas wells by using gas-water relative permeability curves after a comparative study was conducted thoroughly. In this way, quantitative evaluation was performed on production capacity, gas production, ultimate cumulative gas production and recovery factor of water-producing gas wells. Then, a case study was carried out of the tight sandstone gas reservoirs with strong heterogeneity in the Sulige Gas Field, Ordos Basin. This method was verified in terms of practicability and reliability through a large amount of calculation based on the actual production performance data of various gas wells with different volumes of water produced. Finally, empirical formula and charts were established for water-producing gas wells in the Sulige Gas Field to quantitatively evaluate their production capacity, gas production, ultimate cumulative gas production and recovery factor in the conditions of different water-gas ratios. These formula and charts provide technical support for the field application and dissemination of the method. Study results show that water production is serious in the west of this field with water-gas ratio varying in a large range. If the average water-gas ratio is 1.0 m³/10⁴ m³, production capacity, cumulative gas production and recovery factor of gas wells will be respectively 24.4%, 24.4% and 17.4%. If the average water-gas ratio is 2.0 m³/10⁴ m³, production capacity, cumulative gas production and recovery factor of gas wells will be respectively 40.2%, 40.2% and 33.2%.