Experimental Evaluation and Field Application of the FDM-1 Filming Plugging Agent

The lithology of the carboniferous system in the Hudson area is mainly mudstone interbedded with thin sandstones and breccia. Serious sloughing of borehole wall during drilling operation has caused overpull and pipe-sticking. Drilled cuttings sampled by mudlogger have poor representativity, reducing the quality of lithological recognition. In drilling the build-up section and horizontal section of a well, well sloughing has caused inability to exert weight on bit, making well angle buildup and drilling low efficient. Plugging of pore throats through filming of drilling fluid on the surface of borehole wall was introduced to address these problems. In laboratory experiment, a filming agent FDM-1 was evaluated for its filming efficiency using a test method in which volume of solution lost and the volume of filtrate through the filter membrane formed by the dissolved filming agent were used as the evaluation parameters. The functioning mechanisms of FDM-1 in clay slurries were studied. Laboratory evaluation and the practices of field application showed that, as a nanometer-micrometer-sized high polymer emulsion, FDM-1 was able to form a dense polymeric membrane on the surface of porous media after filtration of the liquid in the polymer solution into the media. This polymeric membrane is non-permeable and deformable, and is able to form dense plugging layers inside the formation pores, thus effectively reducing filtration rate of drilling fluid and stabilizing borehole wall. Borehole wall sloughing problem was resolved successfully using FDM-1, and by improving the quality of the mud cakes, good lubrication was achieved, which was beneficial to resolving the problem of inability to exert weight on bit.