Patent ID: 8506837

Claim:
Apparatus for causing a fluid to enter a semi-solid state in the presence of a magnetic field, comprising: a plurality of energy field responsive particles which form chains in response to the magnetic field, the particles selected from the group consisting of: particles in which at least one field-responsive member having a first density is attached to at least one member having a second density that is lower than the first density; shaped particles in which at least one field-responsive member has one or more inclusions; and combinations thereof; a multi-phase base fluid, the multi-phase base fluid mitigating fluid creep between the plurality of energy field responsive particles; and wherein the plurality of energy field responsive particles comprises, a 55% particle volume fraction of particles having particle sizes between 100-300 μm, a 35% particle volume fraction of particles having particle sizes between 20-30 μm , a 10% particle volume fraction of particles having particle sizes between 2-5 μm and wherein the plurality of energy field responsive particles are 60% of a volume fraction of the fluid, the particle sizes reducing a size of a gap between the plurality of energy field responsive particles and mitigating fluid creep.