Preparation method of oil displacement system combining exogenous functional microorganisms and oil reservoir endogenous microorganisms

Abstract

The invention discloses a preparation method of an oil displacement system combining exogenous functional microorganisms and oil reservoir endogenous microorganisms. The preparation method comprises the following steps: determining an endogenous bacterium activator; selecting exogenous functional bacteria, and determining an exogenous bacteria activator; integrating the endogenous bacterium activating agent and the exogenous bacterium activating agent into an endogenous and exogenous bacterium activating agent; determining the proportion of the endogenous and exogenous bacterium activating agent, the exogenous functional bacterium and the oilfield stratum produced water during on-site injection through a physical simulation experiment to obtain the exogenous functional microorganism and oil reservoir endogenous microorganism bacterium combined oil displacement system; the problem that no forming technical scheme exists for microbial oil recovery of high-water-content blocks of grape flower oil layers is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of tertiary oil recovery in oil field development engineering, and in particular to a microbial oil recovery system and a preparation method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] The main oil layer in the periphery of Daqing has entered the late stage of high water content, the remaining oil is dispersed, the proportion of high water content wells and low efficiency wells is high, the water drive development is difficult, the adjustment potential of the injection and production system is reduced, and the recovery rate is low. The Putaohua oil layer in the periphery of Changyuan is the main oil layer of the peripheral oilfield production, and the permeability is mostly 50×10 -3 μm 2 The main oilfield of the Putaohua oil layer has entered the late stage of high water content, and the peripheral oilfields are low-yield, low-permeability, and low-abundance reservoirs. With the continuous deepening of development, the development difficulty is getting greater and greater, and the continuous increase in inefficient blocks has seriously restricted the effective development of the oilfield. Therefore, it is urgent to explore effective ways to improve the recovery rate of the high-water-content blocks of the Putaohua oil layer outside Daqing, and support the peripheral developed oilfields to control the increase in water content and the decline in production.

[0004] Microbial oil recovery has the following advantages: (1) Low construction cost. It can be injected through existing water injection pipelines without adding special pipelines and special equipment; (2) Convenient construction and operation. The microbial formula can be flexibly adjusted according to the specific conditions of the reservoir; (3) For low-yield reservoirs and depleted reservoirs, microbial oil recovery technology can achieve long-term production increase effects; (4) It is suitable for the extraction of various types of crude oil (heavy, light and high-wax crude oil); (5) It is green and environmentally friendly, does not damage the formation, and can be repeatedly used in the same block. It is precisely because of these advantages of microbial oil recovery technology that this technology has strong economic appeal for marginal production oil fields.

[0005] However, there is no direct technical solution for microbial oil recovery in high-water-content blocks such as the Putaohua oil layer outside Daqing.

[0006] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may contain information that does not constitute prior art. Summary of the invention

[0007] In view of this, the present disclosure provides a method for preparing an oil recovery system combining exogenous functional microorganisms with endogenous microorganisms in an oil reservoir, so as to solve the problem that there is no direct technical solution for microbial oil recovery in high water-content blocks of the Putaohua oil layer.

[0008] In order to achieve the above-mentioned invention object, the preparation method of the oil recovery system combining exogenous functional microorganisms with endogenous microorganisms in oil reservoirs comprises:

[0009] Identify endogenous bacterial activators;

[0010] Select exogenous functional bacteria and determine the exogenous bacteria activator;

[0011] Integrating the endogenous bacteria activator and the exogenous bacteria activator into an endogenous and exogenous bacteria activator;

[0012] The ratios of the exogenous and exogenous bacteria activators, the exogenous functional bacteria and the produced water from the oilfield formation during on-site injection are determined by physical simulation experiments, and an oil recovery system combining the exogenous functional microorganisms and the endogenous microorganisms of the oil reservoir is obtained.

[0013] In the present disclosure and possible embodiments, the method for determining the endogenous bacteria activator includes:

[0014] The limiting factors lacking in the growth of endogenous microorganisms are determined by analyzing the water components in the target area, and the endogenous bacteria activator is determined based on the limiting factors.

[0015] In the present disclosure and possible embodiments, the limiting factors are input into an orthogonal design assistant program, and the content of each element of the endogenous bacteria activator is determined by the program.

[0016] In the present disclosure and possible embodiments, the method for selecting exogenous functional bacteria includes:

[0017] The endogenous microbial flora in the formation water of the target block is detected, and the exogenous functional bacteria are selected through a shaking table experiment in view of the absence of hydrocarbon oxidizing bacteria in the injection and production fluids of the oil wells.

[0018] In the present disclosure and possible embodiments, the endogenous bacteria activator and the exogenous bacteria activator are integrated through a shaking table experiment to obtain the endogenous and exogenous bacteria activator.

[0019] Beneficial effects of the present invention:

[0020] In view of the increasing difficulty in developing existing peripheral oil fields and the increasing number of inefficient blocks, the present invention provides a method for preparing an oil recovery system combining exogenous functional microorganisms and endogenous microorganisms in oil reservoirs, which has targeted and reliable effects, effectively solves the problem of the great difficulty in recovery of low-permeability oil reservoirs, and expands the scope of application and application effect of the combined exogenous and endogenous microbial oil recovery technology, effectively solving the problem of no direct application of technical solutions for microbial oil recovery in high-water-content blocks of the Grape Flower oil layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a comparison chart of the results of measuring the gas production of microorganisms activated after endogenous, exogenous, and combined endogenous and exogenous effects in the embodiments of the present disclosure. DETAILED DESCRIPTION

[0022] The present disclosure is described below based on embodiments, but it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, some specific details are described in detail. However, for the parts that are not described in detail, those skilled in the art can also fully understand the present disclosure.

[0023] In addition, those skilled in the art should understand that the drawings are provided only to illustrate the purpose, features and advantages of the present disclosure, and the drawings are not actually drawn to scale. At the same time, unless the context clearly requires, the words "include", "comprise" and the like in the entire specification and claims should be interpreted as inclusive rather than exclusive or exhaustive; that is, "including but not limited to" meaning.

[0024] Example

[0025] Taking a high water-content block of the Putaohua oil layer outside Daqing as an example, microbial oil recovery was carried out for the target block, and the method of the present invention was used to prepare a method for preparing an oil recovery system combining exogenous functional microorganisms and endogenous microorganisms in the reservoir. The specific process is as follows:

[0026] 1. Determination of endogenous bacterial activators

[0027] (1) Experimental conditions: The mineralization of the formation water was 7530 mg / L; the experimental oil was the prepared crude oil with an underground viscosity of 5.2 mPa.s from the peripheral oil field; the experimental temperature was 51.5°C;

[0028] (2) By analyzing the water composition of the injection and production system in the target area, it was determined that the limiting factors for the growth of endogenous functional bacteria were N, P, and a small amount of commonly used trace elements.

[0029] (3) Input the above limiting factors into the cracked version of the orthogonal design assistant program IIV3.1, and set the ratio of the carbon source, P source, and trace elements used. The program uses the orthogonal experimental results to determine the percentage of each element in the activator: 1.8% to 2% C source + 1.2% N source + 2% P source + 0.3% to 0.4% trace elements. The C source of the endogenous bacteria activator determined in this example is corn syrup, and the N source is NaNO 3 , P source is KH 2 PO 4 、Na 2 HPO 4 , trace elements are citric acid, MnCl 2 MgSO 4 .7H 2 0; the composition and content of the endogenous bacteria activator are:

[0030] C source: corn syrup 2%; N source: 1.2% NaNO 3 ;P source: 1% KH2 PO 4 、 1% of Na 2 HPO 4 ; Trace elements: 0.2% of citric acid, 0.01% of MnCl 2 、 0.16% of MgSO 4 .7H 2 0; The balance is water.

[0031] 2. Selection of exogenous functional bacteria and determination of exogenous bacterial activator:

[0032] Through metagenomic sequencing, it is detected that the endogenous bacteria in formation water mainly include Pseudomonas, Wolinella, and Acinetobacter. The typical bacterial types are detected by the extinction dilution method. The typical bacterial types in the injected water are rich, including saprophytic bacteria, nitrate-reducing bacteria, methanogens, and fermentative bacteria. The produced fluid is mainly anaerobic or facultative methanogens and fermentative bacteria. In view of the lack of hydrocarbon-oxidizing bacteria in the injected and produced fluids of oil wells, a group of commonly used hydrocarbon-oxidizing bacterial strains 1# in oilfields, namely Bacillus licheniformis and Bacillus cereus, are selected as exogenous functional bacteria through a shaker experiment.

[0033] In order to further improve the action ability of exogenous functional bacteria, in this embodiment, Bacillus brevis and Clostridium fusiforme are added. Finally, it is determined that the exogenous functional bacteria selected in the embodiment of the present disclosure are Bacillus licheniformis, Bacillus cereus, Bacillus brevis, and Clostridium fusiforme.

[0034] The exogenous bacterial activator selected in the embodiment of the present disclosure has the same carbon source as the endogenous bacterial activator, and it is determined that the N source of the exogenous bacterial activator is NaNO 3 , and the P source is KH 2 PO 4 、 Na 2 HPO 4 ; It is determined that the composition and content of this exogenous bacterial activator are: C source: 2% of corn steep liquor; N source: 1.2% of NaNO 3 ; P source: 1% of KH 2 PO 4 、 1% of Na 2 HPO 4 ; The balance is water.

[0035] 3. Integration of endogenous and exogenous bacterial activators

[0036] Through a shaker experiment, the endogenous bacterial activator and the exogenous bacterial activator are integrated to obtain the endogenous and exogenous bacterial activator, and it is determined that the composition and content of the endogenous and exogenous bacterial activator in this embodiment are: C source: 2% of corn steep liquor; N source: 1.2% of NaNO 3 ; P source: 1% of KH 2 PO 4 、 1% of Na 2 HPO4 ; The balance is water.

[0037] 4. Optimization of oil displacement system

[0038] In the embodiment of the present disclosure, the exogenous functional bacteria and the exogenous and exogenous bacterial activators determined in steps 1-3 are used to react with crude oil. Then, according to the conventional techniques in the art, physical simulation experiments are performed to evaluate the bacterial concentration, surface tension, rheological properties, and wax and gel content. Finally, the exogenous functional microorganisms and reservoir endogenous microorganisms of the embodiment of the present disclosure are combined to obtain an oil recovery system: 1% exogenous functional bacteria (Bacillus licheniformis, Bacillus cereus, Bacillus potssteinii, and Bacillus fusidiformis) + 1% exogenous and exogenous bacterial activators (C source: 2% corn steep liquor; N source: 1.2% NaNO 3 ;P source: 1% KH 2 PO 4 , 1% of Na 2 HPO 4 ; The balance is water) + formation water; The total concentration is 0.2%, and the surface tension of the fermentation liquid of the combined endogenous and exogenous microbial system decreases from 49.5mN / m of the blank to 36mN / m.

[0039] 5. Oil recovery performance evaluation

[0040] (1) Based on the final activation system formula, exogenous, endogenous, and endogenous + exogenous oil displacement experiments were carried out simultaneously, in which the injection volume of exogenous bacterial solution was 2% and the injection concentration of bacterial solution was 10 3 After 10 days of shaking culture, the bacterial concentrations of endogenous, exogenous, and endogenous + exogenous activations increased, with the exogenous bacterial concentration reaching 10 5 The endogenous bacteria concentration is 10 3 The concentration of endogenous and exogenous bacteria is 10 8 The results of the changes in the number of endogenous, exogenous, and endogenous + exogenous microorganisms before and after activation are shown in Table 1:

[0041] Table 1 Changes in bacterial counts before and after activation of endogenous, exogenous, and endogenous + exogenous microorganisms

[0042] Sample name Total bacterial concentration SRB HDB FMB FB TGB NRB MPB Injection of exogenous bacteria <![CDATA[10 3 ]]> blank 0 0 0 0 0 0 0 0 Endogenous <![CDATA[10 4 ]]> 0 <![CDATA[1.3×10 2 ]]> 0 0 0 <![CDATA[7×10 2 ]]> 0 External <![CDATA[10 5 ]]> 0 <![CDATA[7×10 2 ]]> 0 0 <![CDATA[2.5×10 1 > <![CDATA[1.3×10 2 ]]> 0 Internal + external <![CDATA[10 8 ]]> 0 <![CDATA[1.1×10 3 ]]> 0 0 5 <![CDATA[7×10 4 ]]> 0

[0043] (2) The surface tension values ​​of endogenous, exogenous, and endogenous + exogenous sources all decreased, among which the surface tension of the fermentation liquid with endogenous + exogenous sources was the lowest, decreasing from 53.48 mN / m to 32.16 mN / m. The changes in the surface tension of the fermentation liquid after endogenous, exogenous, and endogenous + exogenous sources are shown in Table 2:

[0044] Table 2 Changes in surface tension of fermentation liquid after endogenous, exogenous, and endogenous + exogenous effects

[0045] Sample No. Surface tension (mN / m) blank 53.48 Endogenous 43.44 External 50.97 Internal + external 32.16

[0046] (3) After the action of endogenous, exogenous, and endogenous + exogenous oil displacement systems, the viscosity and rheology of the crude oil are improved. Among them, the effect of the endogenous + exogenous action is the best, with a viscosity reduction rate of 39.18%, and the rheology of the crude oil becomes better. The changes in the viscosity of the crude oil before and after the action of specific microorganisms are shown in Table 3:

[0047] Table 3 Changes in the viscosity of crude oil before and after the action of microorganisms

[0048] Sample No. Viscosity (mPa·s) blank 87.8 Endogenous 84.8 External 76 Internal + external 53.4

[0049] (4) After the action of endogenous, exogenous, and endogenous + exogenous oil displacement systems, the wax and gum contents of the crude oil both decrease. The combined action of endogenous + exogenous has the best reduction effect, and the ∑c21- / ∑c22+ value increases to 1.46. The change results of the wax and gum contents of the crude oil are shown in Table 4, and the change results of the alkane components of the crude oil are shown in Table 5:

[0050] Table 4 Change results of wax and gum contents of crude oil

[0051] Sample No. Wax content, % Glue content, % blank 26.3 18 Endogenous 25.9 17.8 External 25.2 15.2 Internal + external 23.6 15.4

[0052] Table 5 Change results of alkane components of crude oil

[0053] Sample No. Σc21- / Σc22+ blank 1.43 Endogenous 1.42 External 1.41 Internal + external 1.46

[0054] (5) Exogenous, endogenous, and endogenous + exogenous gas production experiments are carried out simultaneously. The cumulative gas production results show that the highest gas production is from the combined endogenous and exogenous oil displacement system, followed by the endogenous system, and the exogenous oil displacement has the worst gas production effect. See specifically Figure 1 .

[0055] Verification example

[0056] For the preparation method of the combined oil displacement system of the above exogenous functional microorganisms and reservoir endogenous microorganisms, the effect is evaluated through physical simulation oil displacement experiments to determine the optimal concentrations of the final in-situ application bacterial liquid and activator, as follows:

[0057] Experimental formation water: The salinity of the produced liquid treated sewage is 7530 mg / L; the experimental oil is the formulated crude oil with an underground viscosity of 5.2 mPa·s in the peripheral oilfield; the experimental temperature is 51.5°C.

[0058] The operation steps of the oil displacement experiment are as follows: evacuate and saturate the core with simulated formation water → saturate with simulated oil → water drive until the water cut reaches 98% and end, calculate the water drive recovery rate → inject the preparation method of the combined oil displacement system of exogenous functional microorganisms and reservoir endogenous microorganisms, and maintain a constant temperature and pressure for 14 days → water drive until the water cut reaches 98% and end, calculate the microbial enhanced oil recovery.

[0059] Oil displacement scheme 1 is a 0.3PV exogenous functional microorganism combined with reservoir endogenous microorganisms to prepare an activation solution for oil displacement system (cultured for 2 weeks) + subsequent water flooding. The three cores used different ratios of exogenous and exogenous combined systems. The experimental results can guide the concentration ratio of the on-site bacterial solution in the oil displacement system. Considering the implementation cost, the bacterial solution concentration was finally determined to be 1%.

[0060] See Table 6:

[0061] Table 6 Results of microbial oil recovery experiments under different bacterial solution concentrations

[0062]

[0063] As shown in Table 6, with the increase of bacterial solution concentration, the recovery rate is effectively improved.

[0064] Oil displacement scheme 2 is an experimental low permeability artificial heterogeneous core, with simulated oil of 5.2mPa.s (50℃), and water injection for water displacement. The experiment was observed at a constant temperature of 50℃ for 14 days. Among them, cores 1-3 are the ratios of activators with different concentrations. According to the experimental results, it can be determined that the optimal concentration ratio of activators for this block is 1%. Core No. 6 is a simulated water displacement experiment, No. 5 is a simulated exogenous microbial oil displacement, and No. 4 is a simulated endogenous microbial oil displacement. The experimental results of these three cores are the same as those of the exogenous bacteria injection concentration of the combined system of exogenous and endogenous microorganisms in core No. 3 in oil displacement scheme 1, and the activator injection concentration is 2%. The injection amount of the entire injection system is consistent, which is equivalent to a comparison of the final recovery degree of water displacement, exogenous, endogenous, and combined exogenous and endogenous sources. According to the experimental results, the final recovery rate of the combined exogenous and endogenous oil displacement system prepared is better. The core experiment results are shown in Table 7:

[0065] Table 7 Results of microbial oil recovery experiments under different activator concentrations and endogenous flooding, exogenous flooding, and water flooding

[0066]

[0067] Through physical simulation tests, the formula of the entire internal and external functional bacteria composite oil-flooding system was determined to be 1% bacterial solution + 1% internal and external combined activator. The oil-flooding system used on site was 0.3PV internal and external mixed solution (1% microbial solution + 1% microbial activator) + water flooding.

[0068] The above-described embodiments are only embodiments of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the present disclosure. It should be noted that, for a person of ordinary skill in the art, without departing from the concept of the present disclosure, several variations, equivalent substitutions, improvements, etc. may be made, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the attached claims.

Claims

1. A method for preparing an oil recovery system combining exogenous functional microorganisms with endogenous microorganisms in oil reservoirs, It is characterized in that include: Identify endogenous bacterial activators; Select exogenous functional bacteria and determine the exogenous bacteria activator; Integrating the endogenous bacteria activator and the exogenous bacteria activator into an endogenous and exogenous bacteria activator; The ratios of the exogenous and exogenous bacteria activators, the exogenous functional bacteria and the produced water from the oilfield formation during on-site injection are determined by physical simulation experiments, and an oil recovery system combining the exogenous functional microorganisms and the endogenous microorganisms of the oil reservoir is obtained.

2. The method for preparing an oil displacement system according to claim 1, It is characterized in that The method for determining the endogenous bacteria activator comprises: The limiting factors lacking in the growth of endogenous microorganisms are determined by analyzing the water components in the target area, and the endogenous bacteria activator is determined based on the limiting factors.

3. The method for preparing an oil displacement system according to claim 2, Features: The limiting factors are input into the orthogonal design assistant program, and the content of each element of the endogenous bacteria activator is determined by the program.

4. The method for preparing an oil displacement system according to any one of claims 1 to 3, It is characterized in that Methods for selecting exogenous functional bacteria include: The endogenous microbial flora in the formation water of the target block is detected, and the exogenous functional bacteria are selected through a shaking table experiment in view of the absence of hydrocarbon oxidizing bacteria in the injection and production fluids of the oil wells.

5. The method for preparing an oil displacement system according to claim 4, Features: The endogenous bacteria activator and the exogenous bacteria activator are integrated through a shaking table experiment to obtain the endogenous and exogenous bacteria activator, and the composition and content of the endogenous and exogenous bacteria activator are determined.

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