Method for oil well water-shutoff by utilizing scleroglucan fermentation liquor

Abstract

The invention relates to a method which utilizes sclerotium rolfii polysaccharide fermentation liquor to carry out oil well water shutoff, comprising the following steps: (1) 0.05 to 2PV of well-washing nutrient solution is injected into an oil well for well-washing in the positive direction; the preparation of the well-washing nutrient solution is that each litre of water contains 5 to 30g of molasses, 0.5 to 2g of KCI, 0.5 to 2g of NaCI, 0.01 to 0.1g of MgSO4, and 0.01 to 0.1g of MnSO4 which are evenly mixed; (2) 0.15 to 2PV of sclerotium rolfii polysaccharide fermentation liquor is injected into the oil well, and according to part by weight, the fermentation liquor contains 0.1 to 2 percent of thalli, and 0.1 to 2.5 percent of scleroglucan; and (3) 0.05 to 2PV of displacement nutrient solution is injected into the oil well, and regular production is recovered after the well is closed for 5 to 7 days; the preparation of the displacement nutrient solution is that each litre of water contains 5 to 30g of molasses, 0.5 to 2g of KCI, 0.5 to 2g of NaCI, 0.01 to 0.1g of MgSO4, and 0.01 to 0.1g of MnSO4 which are evenly mixed. The method has simple operation, selective shutoff is carried out according to the characteristic of the fermentation liquor that the higher part is blocked and the lower part is not blocked by adopting a way of injecting from the oil well, a high permeable zone is blocked, the water-shutoff and oil-dispelling effects are obvious, the cost is lowered, the construction is safe, pollution to the stratum is reduced, and the recovery ratio of crude oil can be greatly improved.

Description

technical field [0001] The invention relates to a biological water shutoff method in the field of oil field application, in particular to a method for oil well water shutoff by using Sclerotinia polysaccharide fermentation liquid. Background technique [0002] Usually the oilfield development enters the middle and late stage, in order to maintain the energy of the formation, the purpose of oil displacement is achieved by continuously injecting water into the formation. Due to the heterogeneity of the oilfield formation, the injected water preferentially enters the high-permeability layer area, thus forming an unreachable area, or even a dead oil area, resulting in a large amount of injected water reactive circulation. Water from oil wells will cause many harms: consumption of formation energy, reduction of ultimate recovery of oil layers; reduction of pumping rate of pumping wells; serious corrosion and scaling of pipelines and equipment; increase of load on dehydration stat...

AI Technical Summary

Problems solved by technology

Although these plugging agents have the characteristics of long delay time and high plugging strength, due to the high temperature of some deep oil wells during the oil well water plugging operation, the viscosity of the water plugging agent will drop sharply, which will affect the water plugging effect; The high-speed shearing when preparing, pumping, and passing through the bottom hole and formation pores will reduce the viscosity of the water shutoff agent and affect the water shutoff effect

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