Developing Cement Mixtures to Cement Horizontal Well Intervals with Multi-Stage Fracturing

摘要

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.