Complex of methods to evaluate inhibiting properties of muds in relation to clay swelling rocks (at example of “reactive” clays of montmorillonite group of Kazanian, Tatarian ages in Permian system)

Abstract

One of complication happening during construction of significant amount of wells in deposits of Denisovian basin of Timan-Pechora oil and gas province is loss of wellbore walls stability in intervals of “reactive” clays of Kazanian and Tatarian ages of Permian system. Complex lithological characterization of falling rocks within the named drilling intervals was performed using X-ray phase, X-ray fluorescence and litho-mineralogical analysis. In result of the study singularities of mineral and chemical composition of rocks and their clay component are determined. The article reviews the results obtained in diversified set of studies of muds inhibiting properties, including the following kinds of tests: study of rock swelling degree; tests to determine erosion of argillaceous slates in mud medium; evaluation of dispersing ability of muds; tests of fracture formation in rock samples in mud medium; study of character and intensity of ion exchange processes behavior in system «rock – mud»; study of alteration of rocks physical and chemical properties after influence of mud. According to results of the study gradation of different mud types according to their inhibiting ability in relation to clay swelling rocks is proposed.

Keywords

• inhibiting ability of muds
• rocks of kazanian
• tatarian age
• litho-mineralogical rock composition
• degree of rock swelling
• degree of rock erosion
• colloidal particles concentration