套管损伤磁记忆检测信号定量研究

在油气生产过程中，井下套管损伤会造成井况恶化，致使正常井转变为套损井。为了防止套损井的出现和安全事故的发生，有必要对套管进行早期损伤检测。采用金属磁记忆检测技术，开展了实验研究。实验中，通过对套管内壁环切，将套管壁厚设计为等值递增和不等值递增两种形式；根据实验数据，对磁记忆检测信号梯度值、信号梯度波峰值及信号梯度峰宽值等特征参量与壁厚、壁厚变化量的定量关系进行拟合。结果表明:磁记忆检测信号梯度值、信号梯度波峰值及信号梯度峰宽值等特征参量，可以很好的表征套管壁厚的变化情况；信号梯度值与套管壁厚呈线性递增关系；信号梯度波峰值和信号梯度峰宽值均与套管壁厚变化量呈线性递增关系。该试验结果有助于完善磁记忆检测技术的定量化研究和利用磁记忆原理检测套管损伤的评价体系。

Quantitative study on magnetic memory detection signal of casing damage

In the process of oil and gas production, the downhole casing damage can cause the worsening well condition, leading to the transition from normal well into casing damage well. In order to prevent the appearance of casing damage well and the occurrence of safety accident, it is necessary to make an early damage detection of the casing. The experimental study was carried out by using the metal magnetic memory testing technology. In the experiment, the casing thickness was designed as two forms including equivalent increment and nonequivalent increment through the ring cutting of inner casing. According to the experimental data, the quantitative relationship between the characteristic parameters of magnetic memory detection signal, such as the gradient value, gradient wave peak value, gradient peak width value and so on, and the casing thickness and the casing thickness variation was fitted. The results showed that the characteristic parameters of the magnetic memory detection signal can represent the change situation of casing thickness well. The signal gradient value presents a linear increasing relationship with the casing thickness, and both the signal gradient wave peak value and signal gradient peak width present the linear increasing relationship with the casing thickness variation. The experimental results are helpful to perfect the quantitative study of magnetic memory testing technique and the evaluation system for magnetic memory testing of casing damage.