环空带压气井液位测试方法改进研究及应用

为了实时有效监测环空带压气井的液面位置，评价环空带压气井的风险,在传统回波定位技术基础上，提出了1种基于自相关分析的气井液位声波测试方法；建立了环空液位声波测试实验系统，开展了不同起爆压力下环空液位测试实验；对检测到声波信号进行平滑降噪和自相关分析，计算液面位置，并与真实液位进行对比分析；将该方法在现场含噪声的环空带压气井液位测试中进行了应用。结果表明:该方法能够对环空液位声波测试信号中的液面反射波进行有效提取；相比较现有在测试信号平滑降噪基础上提取的液面位置，降低了计算误差；同时，该方法能够在井下噪声环境中实现微弱液面反射声波的有效提取，其处理后的信号峰值指标更为突出，提高了测试系统对液位的识别能力，便于自动识别。

Research and application on improved testing method of liquid level for gas well with sustained casing pressure

In order to effectively monitor the liquid level of gas well with sustained casing pressure (SCP) in real-time and evaluate the risk of gas well, an acoustic liquid level testing method of gas well based on autocorrelation analysis was put forward on the basis of traditional echo positioning technology. An acoustic testing experimental system of annular liquid level was established, and the testing experiments of annular liquid level under different initiation pressure were carried out. The smoothing noise reduction and autocorrelation analysis were conducted on the detected acoustic signals to calculate the liquid level, and the results were compared with the real liquid level. On this basis, the method was applied in the liquid level testing of gas well with SCP in the field containing noise. The results showed that this method could effectively extract the liquid surface reflection in the acoustic testing signals of the annular liquid level, which reduced the calculation error compared with the existing liquid level extracted on the basis of smoothing noise reduction. Meanwhile, the method could achieve the effective extraction of weak liquid surface reflection in the underground noise environment, and the peak index of signals after processing by the method was more outstanding, which improves the identification ability on liquid level of the testing system and is convenient for the automatic identification.