A method for endogenous microbial oil recovery in low-permeability reservoirs

Abstract

The invention belongs to the technical field of tertiary oil recovery, and particularly relates to an indigenous microbial oil recovery method for low-permeability oil reservoir. The indigenous microbial oil recovery method comprises the following steps that a test oil reservoir is screened; activators are screened, and the screened activators comprise the activator producing biopolymer functionalbacteria and the activator producing biosurfactant functional bacteria; the injecting mode of the activators are determined; the field test is conducted, and the field test comprises the injecting stage of the activator producing the biopolymer functional bacteria, the injecting stage of the activator producing the biosurfactant functional bacteria and the normal water injecting stage; and the field test effect is evaluated. According to the indigenous microbial oil recovery method for the low-permeability oil reservoir, the using amount of the injection agents can be effectively saved, and the field test effect can be greatly improved; and meanwhile, the indigenous microbial oil recovery method has the characteristics of simple process and high pertinence and maneuverability, thereof, the indigenous microbial oil recovery method can be widely applied to the field test of enhancing oil recovery of the low-permeability oil reservoir.

Description

technical field [0001] The invention belongs to the technical field of microbial oil recovery, and in particular relates to a method for endogenous microbial oil recovery of low-permeability oil reservoirs. Background technique [0002] With the rapid development of our country's economy, the demand for oil is increasing day by day, and the shortage of oil is becoming more and more serious. However, the current oil extraction technology can only recover about 1 / 3-1 / 2 of the reserves, and the remaining recoverable oil reserves are huge, especially in low-permeability oil reservoirs. According to statistics, the national low-permeability oil resources are 53.7 billion tons, accounting for 49% of the total resources; low-permeability oilfields are difficult to exploit, which poses great difficulties to the stable production of oilfields. Therefore, how to develop low-permeability oilfields is an urgent problem for petroleum workers. question. [0003] Microbial oil recovery i...

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Problems solved by technology

But there is following shortcoming deficiency in this invention: (1) bacterial classification YM4 and DP1 of this invention need ferment on ground (workshop), and will be transported to the spot with tank truck liquid, and the time that fermented liquid preserves is short, therefore, not only increase The cost of the field test of microbial flooding is eliminated, and higher requirements are put forward for the on-site injection time of the fermented liquid; (2) the present invention mixes YM4 and DP1 bacterial liquids according to the ratio of 1:1 and injects them from the water injection well simultaneously, For oil layers with lower permeability, the injection of the fermentation broth of the polymer-producing bacteria DP1 is likely to cause serious blockage of such oil layers; and for oil layers with higher permeability, due to the fermentation broth of the biosurfactant bacteria YM4 and the production of The fermentation liquid of biopolymer bacterium DP1 adopts the method of simultaneous injection. Before the fermentation liquid of biopolymer DP1 can be blocked and adjusted, the fermentation liquid of biosurfactant bacterium YM4 has already entered the high temperature along with the injected water. The permeable layer, therefore, on the one hand causes the waste of the fermentation liquid of YM4 bacteria and DP1 bacteria, on the other hand affects the swept volume and oil washing efficiency of the fermentation liquid and injected water, thus affecting the final recovery degree of the oil reservoir

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