| At present the research about cementing displacement drilling fluid retention problem inthe horizontal well mainly adopts three methods that the indoor experiment, site datastatistics and FLUENT software simulation, but the quantitative description is few fordrilling fluid retention principle and retention layer boundary position when laminar displacesin the horizontal well.Based on the wall shear stress theory, combined with balance conditions of the displaceinterface, this paper established mechanics balance equations of the cementing annulusdrilling fluid in the horizontal well.Through analysing the critical condition when the drillingfluid retention happened, combined with the established mechanics balance equations,solved the radial boundary positions of the casing wall and borehole wall respectively whenthe drilling fluid retention happened.Established the boundary position calculation model of drilling fluid retention layerrespectively when the slurry displace in conditions of Penn han rheological model and Powerlaw rheological model, solved retention thickness distribution equations of the drilling fluidat the side of the near casing wall and near wellhole wall in different slurry rheologicalmodels, combined with actual data, drilling fluid retention layer thickness change rule witheccentric degrees is contrasted, when slurry displaces in different rheological models.Through the above research, gives the retention mechanism of the cementing displacedrilling fluid in horizontal well. The radial boundary position and the corresponding retentionlayer thickness are solved in the horizontal well annulus when drilling fluid retention happens.Through refining the drilling fluid retention position, definited drilling fluid retentiondistribution of the specific angle in the horizontal well annulus,making the measures ofcementing operation more targeted,to improve the horizontal well cementing displaceefficiency and cementing quality provide a powerful guarantee. |
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