Injection pretreatment method for oil water well

Abstract

The present invention relates to an oil-water well shifting-in-injection pretreatment method, belonging to the field of oil field production technology. Said method includes the following steps: using pump truck to successively squeeze the prepad fluid formed from expansion-resisting expansion-reducing agent, visbreaking thickness-reducing agent and water-soluble demulsifying agent, aqueous solution-working solution composed of hydrochloric acid, fluohydric acid, corrosion inhibitor-mud acid, iron ion stabilizing agent-NTA, cleanup additive, expansion-resisting expansion-reducing agent, ethylene glycol butyl ether, and visbreaking thickness-reducing agent and clear water overflush fluid into the stratum, closing well and making reaction for 4-6 hr, making flowback, using pH test paper to determine pH, when the pH is equal to 7, stopping flowback, opening well to make normal production.

Description

Technical field: [0001] The invention belongs to the technical field of oil recovery in oil fields, and in particular relates to an oil-water well transfer pretreatment method for improving oil recovery. Background technique: [0002] In the process of oilfield development, due to the gradual weakening of the formation energy, a large amount of crude oil remains in the formation and cannot be exploited, thereby reducing the recovery rate of crude oil. Therefore, in order to recover formation energy and make residual oil be extracted as much as possible, at present, the most commonly used method is to use water flooding for development. At present, water injection development basically adopts the following two forms: 1) New well investment: that is, water injection wells are drilled in new drilling blocks, and water injection development is carried out in the early water injection mode or in synchronization with production. 2) Oil well transfer: that is, due to the rapid dec...

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Problems solved by technology

2) Oil well re-injection: that is, as the oil wells in some blocks increase with the increase of production time, the formation energy drops rapidly, and some oil wells have no production value, but because there are still remaining oil in this block that has not been exploited, that is to a lesser extent

However, there are two problems in the process of water injection development: one is that the water injection reduces the water absorption capacity of the well, changes the fluid characteristics of the oil layer, and forms a blockage in the formation near the wellbore, which causes the injection pressure to increase year by year; the other is that the injected water and the formation water Poor chemical compatibility, severe corrosion and scaling, coupled with poor geological conditions, low permeability, and high mud content of the reservoir, lead to rapid rise in injection pressure and damage to the reservoir

Therefore, the addition of anti-swelling agent has no effect on clay. In addition, due to long-term mining, organic and inorganic scales have already formed in the strata near the well. This kind of scale cannot be removed, and anti-swelling agent alone is effective. no pressure-reducing effect

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