Well completion process improvement method suitable for water-saturated thick silty-fine sand layer

Abstract

The invention belongs to the technical field of special stratum well drilling and pile drilling construction processes, and particularly relates to a well completion process improvement method suitable for a water-saturated thick silty-fine sand layer. The well completion process improvement method comprises improvement of a well drilling mode, a drill bit structure of a circulating drill and chemical wall protection mud. The improvement of the well drilling mode comprises the steps that positive circulation and reverse circulation are combined for operation, that is, a positive circulation drilling machine is adopted for operation when upper-layer geology is drilled, and when the circulating drill bit of the drilling machine enters the silty-fine sand layer, a reverse circulation drillingmachine is used for operation; the improvement of the drill bit structure of the circulating drill is that the upper end of a fixing ring at the top of the drill bit is connected with a wall-protecting steel pipe consistent with the drill bit in outer diameter; and the chemical wall protection mud comprises corn starch, cellulose, sodium carbonate, polyacrylamide and a proper amount of water. Under the combined action of the three modes, the effects that the wall protection of a well wall is good, stable and free of collapse under special geological conditions, the wall protection mud is water-soluble after being over-aged, normal pore-forming wall protection is guaranteed, and the water permeability of a dewatering well is not affected are achieved.

Description

Technical field[0001]The invention belongs to the technical field of drilling and pile drilling construction techniques for special formations, and particularly relates to a method for improving the well formation technique suitable for a thick layer of silt fine sand layer saturated with water.Background technique[0002]During the construction of building foundation pits, we often encounter abundant groundwater. If the groundwater level is higher than the bottom of the excavation, groundwater will continue to infiltrate the foundation pit. To ensure that the foundation pit can be constructed under dry conditions, to prevent slope instability , Foundation quicksand, pit bottom uplift, pit bottom piping and foundation bearing capacity decline, etc., it is necessary to carry out drilling and dewatering to allow groundwater to flow into the dewatering well, thereby reducing the groundwater level, so as to ensure the smooth construction of the foundation pit, so dewatering The water perm...

AI Technical Summary

Problems solved by technology

Among them, bentonite can swell into a paste after adding water, so the clay content in the clay slurry is very high, which will block the permeable water line, which will seriously affect the water permeability of the precipitation well, and cannot guarantee the excavation of the foundation pit without water. construction

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