The complexity of processes, which occur during drilling unstable mudstone formations, and absence of proven methods for estimation of drilling fluid filtrate influence on low-permeability rocks give motivation for search of ways to perform such estimation. The volume of drilling fluid filtrate is one of key factors for stability of mudstone formations. Generally, the increase of filtrate volume decreases the time of stable condition for such formations. In order to reduce the impact of this factor the compositions that used in industrial and civilian construction for ground strengthening were examined. Strengthening compositions consist of strengthening component and solidification / activation component. Sodium silicate and different modifications of carbamide resin can be used as a strengthening component. Water solutions of acids and salts can be used as a solidification component.
This article describes a single-solution formation strengthening compositions in which the mixing of strengthening and solidification component is made on the surface and multi-solution compositions which imply the one-by-one transfer of components to the unstable interval. For quantitative estimation of an effect of strengthening solutions was deigned the approach that at first step includes the bridging of ceramic disk with the lowest allowable permeability. The change of ceramic disk permeability allows to quantify the bridging effect of compositions. At second step the estimation of reaction of strengthening compositions and model rock samples which are loaded at 2,5% of the sample strength limit at constant temperature. The method of forming samples from core material allows to achieve good convergence of results. The time from the start of experiment till the crash of sample or its 15% deformation comparing to initial length is the sample stability time. The result of this work can initiate the process of integration of technologies that used in industrial and civilian construction for ground strengthening in oil and gas wells construction process.
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