Abstract: A method is for sealing a conduit in a sub terrain well bore, where a fluid is present in the well bore. The method comprises the steps of introducing flexible bodies at a position higher in the well bore than the intended position for the seal and being in fluid contact with the intended position for the seal, the flexible bodies having a density that is higher than the fluid in the well bore, allowing the flexible bodies to settle at the intended position for the sealing, and allowing the flexible bodies to consolidate to form a sealing plug in the conduit. Flexible bodies are for use in the method and a method is for introduction of the flexible bodies.