The Method Research Of Well-bore Stability Evaluation In Shale Under Hydration By Well Logging

Shale hydration is one of the main factors causing well bore instability, but now the evaluation of shale hydration is only qualitative, quantitative analysis is very few. In this paper In-depth understanding the hydration mechanism of shale formations, we probe the method of quantitative hydration stress, and established the logging evaluation methods for borehole stability under the conditions shale hydration.By make using of the continuity and high accuracy of well logging data compute the parameters, such as the clay mineral content of clay on shale formation, the clay mineral composition, fabric of shale, shale analysis of physical and chemical properties, as well as hydration stress produced by shale hydration and analysis the impact on well bore stability , further integration of mechanical well bore stability - chemical coupling of logging under the evaluation model calculated to maintain well bore stability "safe mud density Window" development of shale hydration logging borehole stability evaluation software system, and the actual data processing and analysis result show that the method of this paper can be more intuitive characterization of the important factors wellbore stability ,and plays an important role in guiding the design of sloughing drilling fluid.