Summary The well casing practice shows that cement stone ensuringcasing integrity can destroy under the impact of loads during performance of different process operations. Dynamic impact violates casing integrity most seriously. The potential consequences are inter-casing and behind-casing cross flows, bottom water breakthroughs into a perforation interval, premature water flooding. The currently used cementing materials based on Portland cement resist shock loads inadequately and have a low tearing strength. Many complications connected with premature water flooding directly depend on the low deformation capacity of cement stone. This work suggests methods to solve the problem of annular isolation integrity destruction on the basis of a range of studies, and namely: calculation of the required cement stone strength to prevent its destruction behind casing during perforation and fracturing operations; assessment of the currently used cementing materials to check their ability to ensure the required strength; assessment of cement stone stress via the finite elements method; graphical representation of the stress condition of cement stone by means of the Mohr theory.

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The article is devoted to the quality of well casing at the Pyakyakhinskoye oil and gas condensate field. The issue of improving the quality of well casing is associated with many problems, for example, a large amount of work on finding the relationship between laboratory studies and actual data from the field; the difficulty of finding logically determined relationships between the parameters and the final quality of well casing. The text gives valuable information on a new approach to assessing the impact of various parameters, based on a mathematical apparatus that excludes subjective expert assessments, which in the future will allow applying this method to deposits with different rock and geological conditions. We propose using the principles of mathematical processing of large data sets applying neural networks trained to predict the characteristics of the quality of well casing (continuity of contact of cement with the rock and with the casing). Taking into account the previously identified factors, we developed solutions to improve the tightness of the well casing and the adhesion of cement to the limiting surfaces.

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