The influence of anti-sedimentation agents on the technological parameters of cement slurry

Abstract

Recently, the intensifying development of shale drilling has contributed to the more numerous realization of directional and horizontal boreholes. Moreover, such boreholes are more advantageous as they provide about 4 times higher production than in their vertical counterparts, give access to poorly drained areas, or production of already developed reservoir, where only a new borehole has to be introduced to the network. It should be stressed that the sealing of the casing columns is a challenge because of the restrictions set before drilling fluids used for sealing horizontal boreholes. Slurries play a special role while sealing horizontal boreholes and therefore their technological parameters and density should be adjusted to the geological-reservoir conditions. At the stage of designing slurries for sealing horizontal boreholes, the most important parameters are: sedimentation stability, zero water settling water settling and low filtration. Meeting these requirements was possible by selecting proper admixtures and additives, which in turn, is a guarantee of the uniform and homogeneous structure of fresh and hardened cement slurry. Thus formed cement sheath of bounded slurry should be impervious to gas and have good mechanical properties over the length of the sealing without any trends of anisotropy of the medium in particular points. Modification and designing specialist recipes for definite technological conditions lie, among others, in choosing proper slurry additives and admixtures. However, obtaining appropriate parameters for given conditions may be connected with a change of other parameters deciding about the efficiency of the sealing of a given horizon. Therefore while working out a new recipe for a slurry, the designer should account for the analytical results and influence of the applied agents on all of the parameters of slurry. This is the subject matter of the paper.