气驱特征曲线在气窜模式识别中的应用

Gas drive characteristic curve in gas channeling pattern recognition

水驱特征曲线法分析生产动态普遍应用于水驱油田的开发实践中,但针对渤海气驱油藏缺乏相似的研究手段。基于稳定渗流理论,进行了气驱特征曲线公式的推导,公式表明,达到稳定气驱阶段后,可以认为气顶累积产出量与累积产油量在半对数坐标上成一条直线关系。实际气驱曲线受前期无气采出阶段和后期气携油阶段的影响,为反S型。锦州X油田结合气驱特征曲线划分出3种气窜模式:快速气窜型、稳定气驱型、高气油比型。快速气窜型油井产量递减快、累计产油量低,无稳定生产阶段;稳定气驱型油井气油比上升平缓、持续稳产、累计产油量高;高气油比型油井开发效果介于快速气窜型与稳定气驱型的开发效果之间,开发后期由于气顶气突破与原油脱气,油井逐渐以产气为主,仅携带少量原油,井别性质从油井向气井过渡。在明确气窜规律的基础上,结合控气技术应用实践,提出分气窜模式、分开发阶段的开发策略,针对快速气窜型油井,优化井位,原井眼向下侧钻,改善了开发效果;针对稳定气驱型油井,初期控制合理采油速度,中后期跟踪气油比上升幅度配套控气措施,气油比呈现出波动式上升规律;高气油比型油井受高气油比影响,仅携带少量原油,井别性质从油井向气井过渡,计算实施屏障注水,解决气窜问题。研究成果对渤海气驱油藏的生产开发具有一定的指导意义,可实现相似油田动态跟踪与开发调整。

The water drive characteristic curve method to analyze production performance is widely used in the development practice of water drive oil fields,but there is a lack of similar research methods for Bohai gas drive reservoirs.Based on the theory of stable seepage flow,the gas drive characteristic curve formula is derived.The formula shows that after reaching the stable gas flooding stage,the cumulative gas cap production and the cumulative oil production can be considered to be in a straight line relationship on a semi-logarithmic coordinate.The actual gas drive curve is affected by the early gasless production stage and the later gas-carrying stage,and it is inverse S-shaped.The JZ-X oilfield is divided into three gas channeling modes based on the gas drive characteristic curve:fast gas channeling type,stable gas drive type,and high gas-oil ratio type.Fast gas channeling oil wells have a rapid decline in production,low cumulative oil production,and no stable production stage;stable gas drive oil wells have a gentle rise in gas-oil ratio,sustained stable production,and high cumulative oil production;development effects of high gas-oil ratios are between fast gas channeling type and the stable gas flooding type.Due to gas breakthrough in gas cap and crude oil degassing in the later stages of development,oil wells gradually produce gas mainly,carrying only a small amount of crude oil.The nature of the well transits from oil well to gas well.On the basis of clarifying the gas channeling pattern,combined with the application of gas control technology,the development strategy of dividing gas channeling mode and development stage is proposed.For rapid gas channeling type,well position is optimized and original wellbore is sidetracked,and the development effect is improved;for stable gas drive type,rational oil production speed shall be controlled at the initial stage,following the gas-oil ratio increase in the middle and late stages to support gas control measures.The gas-oil ratio shows a fluctuating upward pattern;for high gas-oil ratio type,the oil well is only affected by the high gas-oil ratio,carrying a small amount of crude oil.The nature of the well transits from oil well to gas well.Barrier water injection method is implemented to solve the problem of gas channeling.The research results provide guidance for the production and development of Bohai gas drive reservoirs and can realize the dynamic tracking and development adjustment of oil fields of the same nature.