摘要：The Kaiser Effect experiment is an efficient method to obtain the in-situ stress in the laboratory, which is of guiding meaning for drilling and fracturing in the petroleum industry. However, different loading rates have an unknown influence on this effect. Therefore, it is inevitable to investigate in itsinfluence of loading rates on Kaiser Effect to obtain accurate in-situ stress. With the combination of MTS816 Rock Testing System and SAMOSTM Acoustic Emission Detection System, the curves demonstrating the relationships between the stresses corresponding to Kaiser Effect of sandstone, gritstone as well as mudstone and acoustic hits under different confining pressures determined by simulated well depths were obtained, which were subsequently utilized to calculate and further correct the in-situ stresses. The results showed that the curves could be subdivided into four stages: micro-fissure compaction stage, acuteness zone, descent zone, and quiet area. As for sandstone, gritstone, and mudstone, the stress of the Kaiser Points increased dramatically with the rise of the loading rate, while regarding brittle rocks such as limestone, loading rates had a mild influence on Kaiser Effect. After corrected by loading rates, the test values got closer to the real values and the relative error declined from 9.028% to 1.954% averagely. In conclusion, when calculating in-situ stress with Kaiser Effect, a reasonable loading rate is necessary. This is because at low loading rates, the large cracks and the microcracks inside the core will be displaced and expanded, resulting in an obvious acoustic emission signal, and thus a smaller stress corresponding to Kaiser Point while at high loading rate, only large cracks will be displaced and expanded, and hence the stress is relatively large.
关键词：Kaiser effect;in-situ stress;lithology;loading rate;acoustic emission;oil and gas exploration
