气井控制储量递增规律及早期预测

Incremental law and early-stage prediction of single well controlled reserves

气井控制储量随着生产的持续逐渐增加,具有递增性。理论上,控制储量随着生产井压力激动扩展,由小增大,如果没有界面分隔或其他激动井干扰,控制储量是无限增加的。但在实际矿场中,控制储量增长是有止境的。随着生产时间延续,控制储量逐渐达到一个稳定值,物性条件相对好的储层,达到稳定值所需的时间相对短一些;反之,达到稳定值所需的时间相对长一些。针对气井控制储量递增性,研究了控制储量递增规律,在无因次图版上基本表现特征为:压力激动波及分隔界面前,控制储量递增规律为一斜率为π的直线(简称"π斜率线");当压力激动波及分隔界面后,控制储量递增趋势偏离"π斜率线"。井距分隔界面越远,偏离"π斜率线"的时间越晚;供气边界形状不同,偏离"π斜率线"后的变化趋势也不同。根据控制储量递增规律,拟合气井控制储量早期变化历史,分析供气边界形状,预测有限未来(比如365d)能够控制的储量,可为尽早认识气井及气藏的生产能力提供依据。

Single well controlled reserves increase incrementally with the production. In theory, controlled reserves will increase as the surge pressure extends; if without separated interfaces and active well interference, the controlled reserves will increase infinite ly. However, in practice, the controlled reserves will reach a stable value in production. Meanwhile, the reservoir with better physi cal conditions takes shorter time to reach the stable value than the one with Worse conditions. A study is performed of the progressive increase laws of the single well controlled reserves. The following features are shown by a dimensionless type curve： the increase presents a straight line with zr slope （abbreviated as π slope line） before surge pressure spreads to the separated interface, while the increasing trend deviates from the ~r slope line after surge pressure spreads＇to the separated interface; the farther the well is away from the separated interface, the later the trend deviates from the π slope iine; the trend of deviation depends on the shape of gas supply boundary. The progressive increase laws of single well controlled reserves will be used to fit the previous records of the con trolled reserves changing in a gas well, to analyze the shape of gas supply boundary, and to forecast the dynamic reserves within a limited future time （e. g. , within 365 days）, thereby to provide an evidence to the understanding of the productivity of a gas well and the yield of a gas reservoir.