Water-shutoff method for sealing gas well effluent section by combination of incline cement and gas injection compression

Abstract

The invention relates to a water shutoff method for closing a water-yielding region of a gas well by utilizing dumping cement for matching with gas injection and compression. Gas injection is carried out to a target well so as to shove stored water in the well to the stratum and cause the well to maintain no water; meanwhile, a dump bailer is dropped down by a cabled twist and caused to be vertical to the section to be closed in the stratum; when reaching the closed section, the opening of the bottom of the dump bailer is opened to lead laitance arranged inside to flow out; the laitance flows out and first accumulates in the closed section and then slowly flows to a sieve tube and the gravel stratum in annular rings among the well wall, and gas injection is continued until the laitance solidifies and hardens so as to fulfill the purpose of blocking up the water-yielding stratum.

Description

technical field [0001] The invention relates to a water plugging method for closing the water outlet section of a gas well by using tilting cement combined with gas injection and pressurization, in particular, it refers to the treatment of the water outlet situation of the gravel-filled gas well water cone, and pushes the accumulated water by means of gas injection and pressurization Return to the formation, and squeeze the cement milk to the gap between the gravel and the well wall, and the cement milk will solidify and seal, so that the section will form a reliable closed section. Background technique [0002] During the production of gas wells, there are natural gas and water in the strata that are exploited. The specific gravity of natural gas is lower than that of water, so the natural gas will be stored on the water surface. During the production of natural gas, the pressure of the gas storage layer will gradually drop, and the The water will gradually rise close to th...

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Problems solved by technology

[0009] However, this construction method has several disadvantages. First, it must overcome the dilution effect of cement milk (or resin) mixed with formation water, otherwise there will be problems in subsequent curing Furthermore, it is necessary to ensure that the gravel layer is not subject to excessive fouling and uneven conductivity. The role of the gravel layer is to prevent sand. After production, the gravel layer will inevitably be fouled by silt from the production layer. Milk or resin, even if it can flow into the gravel layer by gravity alone, may not be able to fill all the pores and therefore not completely seal off the bottom water cone

In addition, after water comes out of the production well, there is usually water column accumulation at the bottom of the well. When the cement milk or resin is placed at the bottom of the well, the formation water will form a film on the well wall. When the cement milk or resin is cured and the well is restarted , There is often a differential pressure of tens to hundreds of pounds between the bottom of the well and the formation. This differential pressure will cause the bottom water to flow into the well along the tiny gap between the cement emulsion and the well wall, and cannot completely seal the water layer. As mentioned above , water plugging with thermosetting resin, when the differential pressure at the bottom of the well exceeds 50 pounds, the formation water will penetrate the joint between the gravel layer and the well wall

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