不同温度钻井液浸泡岩石对其表面形貌的影响

为揭示钻井液浸泡岩石产生表面形貌损伤引起井壁失稳，选取砂岩、页岩岩样，利用三维光学显微镜，对不同温度钻井液浸泡作用前后的岩石表面形貌进行测试，定量分析其特征参数，探讨温度对岩石表面形貌的影响机制及损伤度。结果表明:随温度的升高，特征参数S_a、S_q、S_k整体上呈增大趋势，特征参数S_r整体上呈减小趋势，导致其形貌轮廓的粗糙度、离散性、波动性增加，轮廓起伏度降低，对称性优于浸泡前；在30～120 ℃时，形貌损伤度逐渐增加，在120～150 ℃时，形貌损伤度降低，形貌损伤度极值点T_S在120～150 ℃之间。砂岩和页岩的高度特征参数的损伤度大于纹理特征参数的损伤度。 

Effects of Drilling Fluid Soaking on Surface Morphology of Rocks at Different Temperatures

Soaking of rocks in drilling fluids often causes the surface morphology of the rocks to be damaged, which is probably related to the collapse of borehole walls. To reveal the relationship between the two phenomena, sandstone and shale samples were selected to test using 3D optical microscope for their surface morphology prior to and after soaking in drilling fluids at different temperatures. The characteristic parameters of the rocks were quantitatively analyzed and the effects on and damage to the surface morphology of the rocks by temperature investigated. It was found that as temperature increases, the characteristic parameters S_a, S_q and S_k also increase, while the characteristic parameter S_r decreases, resulting in increases in the roughness, discreteness and volatility of the morphologic contour of the rocks, reduction in the relief of the rocks and better symmetry of the rocks after soaking than before. In the temperature range of 30-120 ℃, the degree of morphology damage is gradually increasing with temperature, in the temperature range of 120-150 ℃, the degree of morphology damage is gradually decreasing with temperature. The Ts, which is the extreme value of the degree of morphology damage, lies between 120 ℃ and 150 ℃. Compared with sandstones, shale has a bigger relative degree of damage. Compared with the degree of damage of the rocks measured with texture characteristic parameters, degree of damage of the rocks measured with height characteristic parameters is bigger.