Preparation method and application of decompression and augmented injection agent for water injection well

Abstract

The invention provides a preparation method and application of a decompression and augmented injection agent for a water injection well. The decompression and augmented injection agent comprises the following components: 2-5% of an organic matter degradation agent, 10-15% of a chelating agent, 0.5% of a scale inhibitor, 0.5% of a composite surfactant and the balance of water. The invention further relates to application of the decompression and augmented injection agent for a water injection well. According to the invention, the chelate is subjected to complex reaction with inorganic scales in a water injection string, a near-well bore zone and a deep reservoir, so that the inorganic scales are converted into soluble complexes; the vegetable gum and the polymer residues are degraded by using an organic blocking remover; a composite surfactant with ultra-low interfacial tension is used for stripping residual oil on the surface of stratum rock, and finally plug removal and oil displacement of immediate vicinity of well bore and deep stratum are achieved. The technical defects of conventional acidification and surfactant well washing of the water injection well in the prior art are overcome, and the decompression and augmented injection agent has the advantages of being large in plug removal radius, good in pressure reducing and injection increasing effect, low in cost, simple in construction procedure, safe, environmentally friendly and the like.

Description

Technical field [0001] The invention belongs to the field of water injection development in oilfield; Background technique [0002] Watering is one of an effective increasing measures for oil and gas reservoir development. The development of water is to maintain or improve oil-layer pressure, and achieve high yield of oilfield and obtain a higher incidence of higher collection rates. However, with the development of oilfield water injection development, most oilfield has decreased the oil-absorbing capacity, and the injection pressure of injection molding, which causes a year-on-year rise, resulting in a high pressure area near the injection well, reducing effective injection pressure difference, resulting in a quick amount of water injection More than 85% of the injection of the injection should be injected into the pressure of the pipeline, so that the injection of the injection well cannot be performed normally according to the design. Long-term high-voltage defaults not only ...

AI Technical Summary

Problems solved by technology

Although the existing technology has alleviated the problems existing on the spot, there are still many technical problems, which can be roughly summarized as follows: (1) physical methods: such as techniques such as fracturing and hydraulic jetting, although the effect is better, the construction is complicated, High cost is not conducive to large-scale use; (2) Chemical methods: such as acidification and deep oxidation measures, because the acid reacts quickly with formation scales and rocks, it can only limitedly relieve the blockage caused by scaling near the wellbore , can not carry out deep plugging removal to farther places in the formation. In addition, strong acidic substances are likely to cause potential harm to equipment, personnel, environment and formation. Although its cost is low, it is not conducive to long-term large-scale use; Pressure-increasing injection agents are not effective in reducing the increase in water injection pressure caused by the increase in capillary resistance caused by changes in the wettability of the formation core surface, especially for the increase in water injection fracturing caused by inorganic scale.

In addition, its high cost and long-term injection will also cause potential harm to formation water quality and bring difficulties to subsequent flowback fluid treatment

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