Reduction-oxidation processes as the cause of shales instability

摘要

Coexistence and interaction of chemcial elements with various valence forms,or their complexes in a water based drilling fluid define a cumulative reduction-oxidation (redox) condition of a drilling fluid,its chemcial activiyt and physico-chemcial properties.Filtrate of a dirlling fluid thermodynamcially activate redox paris of checmial elements that are incorporated in a structure of shales being drilled,and proceeding thus redox reaction cna cause explosive-like disruption of crystal structure of minerals.In the report the data of laboratory investigations and results of the analysis of the reasons for well bore instability in a deep well asserting a possibility of explosive-like disruption of natural porperties,and destabilization of shales resulted from their redox interaction with a drilling fluid.