| 摘要 |
Shear thickening fluids which comprise a water swellable material (e.g., clay), capable of rapidly forming a paste having a strength of at least 1000 Pa with the aqueous solution employed and present in sufficient concentration to form such a paste a nonaqueous hydrophobic material comprising a hydrocarbon material and a surfactant and/or strengthening agent, and an aqueous solution comprising water and a water swellable/ water soluble polymer, wherein the clay and water-polymer solution are kept separated by an intervening hydrocarbon-surfactant phase. Preferable, the hydrocarbon-surfactant phase (oil phase) encapsulated clay is suspended in a continuous phase comprising the water-polymer phase; however, suspension of clay and separate, discrete water-polymer droplet in a continuous oil phase are also possible as are compositions commonly called "double emulsions", as well as systems which are bicontinuous. The intervening oil phase prevents the interaction between the water-polymer and the clay phases and results in a stable, non-reacting, pumpable composite, until such time as the oil barrier is ruptured by deliberate application of a sufficiently high shear force. Upon such rupture, the materials mix and interact resulting in a semi-rigid high strength paste. Various well control problems such as oil and gas well blowouts can be controlled by use of the above-described composite. The composite is pumped down the well pipe. Upon application of a sufficiently high shear as by exiting the orifices of the drill bit, needed to rupture the oil envelope, the clay and the water-polymer interact, resulting in the formation of the semi-rigid, high strength paste which cures the well control problem, sealing the well circulation thief zone or terminating or preventing a blowout. |
