| 摘要 |
In placing a plug in a well (1) filled with a fluid (3) by pumping a soln. (10) through pipes (4) in the well, where the soln. contains a polymerisable substance and a Lewis acid catalyst, and is adapted to form a solid plug by polymerisation at the temp. and pressure at the lower end of the pipes (4), the physio chemical properties of the soln., esp. the bulk wt. and the viscosity, are adjusted so that the vol. injected remains in place in the fluid, close to the injection level (2) and that dilution and/or solubilisation between the soln. and the well fluid is low. and the proportions of the components of the soln. are controlled to give a delay before the start of solidification at least equal to the time of positioning in the well. The polymerisable material is pref. an aq. mixt. of melamine-HCHO resin and the viscosity is controlled to be at least equal to that of the fluid by addn. of a polysaccharide viscosifier, e.g. xanthane or scleroglucane, the bulk vol. is brought to about equal to that of the fluid by addn. of an inert filler, e.g. fly ash, and the delay in solidification is controlled by varying the amt. of catalyst, comprising NH4Cl, p-toluene sulphonic acid, tartaric acid, formic acid and/or oxalic acid. The plug obtd. after polymerisation pref. has a mechanical resistance to compression of 5-15 MPa. The fluid (3) is pref. sea water. A liq. in which the polymerisable substance is not soluble, e.g. a mixt. of organic fluids with bulk wt. close to that of the fluid, is injected before the soln. A cement slag may be injected above the (partly) polymerised plug of soln. USE - For plugging of very permeable geological formations which may be crossed by a well, with the soln. penetrating into the permeable zones. The plug can be destroyed by drilling, while preserving the plugging of the well walls at the level of the formations.
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