Abstract: The diffusion-absorption constant of the system composed of shale formation and mud, and the absorbed water incremental distribution at any time are significant parame-ters for studying wellface stability in shale formation. Its influence factors are quite com-plicated and therefore, are difficult to determine through simple laboratory experiment.
Starting from the rock current experiment of the laboratory long core, this paper makes a research on the method of using log information to determine deffusion-absorption con-stant and absorbed water incremental distribution. The conclusions of the research indi-cate that diffusion-absorption constant and absorbed water incremental distribution can be determined solely through quantitative analysis of rexistivity profile of invasion zone in
the state of static filtration.

Key words: Water sensitivity, Hydrachemistry, Mudstone, Shale, Clay stabiliza-tion, Hole sloughing prevention