CN110055044B - A dual control and flooding system for high-temperature and high-salt heterogeneous reservoirs and its application - Google Patents

Abstract

The invention discloses a high-temperature and high-salt heterogeneous oil reservoir dual control and flooding system and its application. '-Methylenebisacrylamide, acrylamide, vinylpyrrolidone and deionized water to prepare water phase solution, oleic acid and oil phase to prepare oil phase solution, and mix the two under the action of inert gas atmosphere and initiator When the dual control and flooding system prepared by the present invention is applied to the chemical flooding of high-temperature and high-salt heterogeneous reservoirs, the interfacial tension of oil and water can be reduced to ^10-2 to ^10-3 mN/m, and the water content is low At 90%, the dual control system can emulsify crude oil to form a water-in-oil emulsion, the viscosity of which is higher than that of underground crude oil; the droplet size of the emulsion can be controlled, and the heterogeneity of the reservoir can be improved through the Jamin effect. Microsphere coupling control can significantly improve the recovery of high-temperature and high-salt heterogeneity reservoirs.

Description

A dual control and flooding system for high-temperature and high-salt heterogeneous reservoirs and its application

technical field

The invention relates to the technical fields of oilfield chemistry and oilfield development, in particular to a high-temperature and high-salt oil reservoir dual control and flooding system and its application.

technical background

At present, many old oilfields have entered the middle and late stages of development. High water content in produced fluids is a serious problem that has plagued oilfield development for a long time. How to effectively control water and stabilize oil production is an important task for oilfield development at this stage. Chemical flooding technology has become the main means to control water, stabilize oil and further enhance oil recovery in mature oilfields, and has been widely used in conventional oil reservoirs. These chemical flooding technologies mainly include: polymer flooding, alkali flooding, surfactant flooding, polymer/surface binary flooding, poly/alkali/surface ASP flooding, and multi-component foam composite flooding. However, for high-temperature, high-salt and strong heterogeneity reservoirs, the application of these chemical flooding technologies still has certain limitations, mainly as follows: 1) The temperature and salt resistance of polymers is limited. It is only suitable for low-temperature and low-salinity reservoirs; 2) Alkali flooding under high calcium/magnesium conditions will cause serious alkali scaling and cause damage to formations; 3) Although foam flooding can be applied in high-temperature and high-salt reservoirs, However, in reservoirs with strong heterogeneity, foam will be produced along high-permeability channels; 4) Some surfactants have good temperature and salt resistance, but in reservoirs with strong heterogeneity, the flow phenomenon serious.

A large number of laboratory experiments and field tests have proved that polymer microspheres can effectively improve formation heterogeneity and expand the swept volume of the swept water phase. At the same time, the influence of temperature and salinity on its adaptability is small, the dosage is low, the cost is low, and the validity period is long. It is especially suitable for high-temperature and high-salt heterogeneous reservoirs. The ability of the ball to improve formation heterogeneity is weakened, and it cannot be well adapted to the reservoir.

Invention content:

Aiming at the shortcomings of current chemical flooding in oil fields, the present invention proposes a dual control and flooding system for high-temperature, high-salt heterogeneous reservoirs, which can not only make up for the limitations of conventional polymer microspheres, but also improve economic benefits.

To achieve the above object, the present invention provides the following technical solutions:

A dual control and flooding system for high-temperature, high-salt heterogeneous reservoirs, made of the following raw materials in terms of mass percentage:

a. Oil phase: 40% to 70%,

Oleic acid: 0.5% to 2%,

b. Water-soluble monomer:

Alkanolamide: 6% to 8%,

Alkylphenol polyoxyethylene ether sulfonate surfactant: 1% to 2%,

Acrylamide (AM): 10% to 20%,

Vinylpyrrolidone (NVP): 1% to 3%,

N,N'-methylenebisacrylamide (MBA): 0.1% to 0.4% of the total mass of water-soluble monomers,

c. Initiator: 0.01% to 0.05% of the total mass of water-soluble monomers,

d. The rest is deionized water;

The preparation of the control and flooding system comprises the following steps:

(1) Water phase solution preparation: add acrylamide, vinylpyrrolidone, N,N'-methylene bisacrylamide, alkanolamide and alkanol polyoxyethylene ether sulfonate surfactants to the deionized water, stir until the solution is clear and transparent, set aside.

(2) Oil phase solution preparation: add oleic acid into the oil phase, stir evenly until the solution is clear and transparent, set aside.

(3) Preparation of emulsion system: Add the oil phase solution into a three-necked flask with mechanical stirring and inert gas inlet/outlet, and slowly add the water phase solution into the In the oil phase solution, after the addition is complete, the inert gas is introduced for 30 minutes, so that the emulsion system is in a deoxygenated condition, and then the mechanical stirring rate is reduced to 200min~400r/min, and the temperature of the three-necked flask is raised to 45℃~50℃ after adding the initiator. After 2h to 3h, a dual control system with a polymer microsphere size of 0.1 μm to 100 μm is formed.

Further, the oil phase is at least one of kerosene, white oil and diesel oil.

Further, the inert gas is one of helium, nitrogen or argon.

Further, the simplified structural formula of the alkyl alcohol amide is:

C _n H _2n+1 CON(CH ₂ CH ₂ OH)

Among them, n is 11-15.

Further, the simplified structural formula of the alkylphenol polyoxyethylene ether sulfonate is:

Among them, m is 8-10, and o is 10-40.

The invention also discloses the application of a dual control and flooding system for high-temperature and high-salt heterogeneity reservoirs, which is mainly used in chemical flooding of high-temperature and high-salt heterogeneity reservoirs.

Compared with the existing control and drive system, the present invention has the following beneficial effects:

1. The dual control and flooding system can reduce the oil-water interfacial tension to 10 ^-2 ~ 10 ^-3 mN/m, and when the water cut is lower than 90%, the dual control system can emulsify crude oil and form a water-in-oil emulsion.

2. The viscosity of the emulsion is different when the water content is different, and its viscosity is higher than that of underground crude oil. When the water content is in the range of 30%-90%, the viscosity of the emulsion is several times that of crude oil, showing Good mobility self-control ability.

3. The droplet size of the emulsion is controllable, and the heterogeneity of the reservoir is improved through the Jamin effect. At the same time, it is coupled with microspheres to further improve the heterogeneity of the reservoir and significantly increase the heterogeneity of high-temperature and high-salt oil. Tibetan recovery rate.

Description of drawings:

Figure 1. Effect diagram of polymer microsphere control and flooding experiment;

Fig. 2. The effect diagram of the control and drive test of the dual control and drive system.

Detailed ways:

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The present invention will be further described below in conjunction with the embodiments and accompanying drawings, but the present invention is not limited.

Example 1:

(1) Preparation of dual control and flooding system for high-temperature and high-salt heterogeneous reservoirs

The experiment needs to prepare the oil phase solution and the water phase solution respectively. The oil phase solution is a mixed system of white oil and oleic acid, and the water phase solution is deionized water, acrylamide, vinylpyrrolidone, alkanolamide and N,N-ethylene oxide. Mixed systems of methacrylamide.

(1) Preparation of oil and water phase solutions

Oil phase solution: Measure 60mL of white oil and 2g of oleic acid, and mix them evenly by ultrasonic stirring.

Aqueous phase solution: Measure 40 mL of deionized water, 15 g of acrylamide, 2 g of vinylpyrrolidone, 0.4 g of N,N-methylenebisacrylamide, and 8 g of alkanolamide, and stir ultrasonically until completely dissolved.

(2) Preparation of inverse microemulsion

a. Add the oil phase solution into the three-necked flask, and slowly add the water phase solution into the oil phase solution at a stirring speed of 900r/min. The time for dropping is controlled at 30 minutes. After the dropping is completed, connect the nitrogen source and stir for another 30 minutes;

b. Reduce the stirring speed to 400r/min, and slowly add 2mL of 1% azobisisobutylamidine hydrochloride solution. After the addition is complete, raise the system temperature to 48°C and continue the reaction for 3 hours to obtain high temperature and high temperature. Dual control and flooding system in salt heterogeneous reservoirs.

(2) Performance test:

1. The ability of the dual control system to reduce interfacial tension

Prepare 100mL of simulated formation water with a salinity of 50000mg/L (Ca2+, Mg2+ concentration is 500mg/L) and 100000mg/L (Ca2+, Mg2+ concentration is 1500mg/L), then add 1g of the above system, stir evenly, at 90 The TX500C rotating interfacial tensiometer was used to test the stable interfacial tension value between the dual control system and different crude oils under the condition of ℃. The experimental results are shown in Table 1. The dual control system can reduce the oil-water interfacial tension to 10 ^-2 ~ 10 ^-3 mN/m, and the present invention shows good oil washing performance.

Table 1 The ability of dual regulation system to reduce interfacial tension

2. The emulsifying ability of the dual regulation system

Prepare 100mL of simulated formation water with a salinity of 50000mg/L (Ca2+, Mg2+ concentration is 500mg/L) and 100000mg/L (Ca2+, Mg2+ concentration is 1500mg/L), then add 1g of the above system, stir evenly, according to different The ratio is mixed with crude oil, put into a three-necked flask with a magnetic stirrer, and stirred for 1 hour at a temperature of 90°C and a stirring rate of 400r/min. Test the viscosity of the emulsion. The experimental results are shown in Table 2: when the water content is less than or equal to 90%, the oil-water emulsification forms a water-in-oil emulsion, and its viscosity is greater than that of crude oil; when the water content is in the range of 30%-90%, the emulsion The viscosity is several times that of crude oil, showing good mobility self-control ability.

Table 2. Emulsification performance of dual control and flooding system and crude oil (viscosity 9.8mPa·s)

3. The ability to adjust and drive the dual regulation system

System preparation: Prepare 100mL of simulated formation water with a salinity of 100000mg/L (Ca2+, Mg2+ concentration is 1500mg/L), then add 1g of the above system and stir evenly.

In order to compare and study the performance of the polymer microsphere system and the dual control system, take 50mL of the dual control system in Example 1, use ethanol to break the emulsion and dry to obtain the polymer microspheres, and take 1g of the polymer microspheres and add them to 100mL The above simulated formation water was used for comparative experiments.

Experimental temperature: 90°C

Oil displacement performance: Through double parallel core experiments, under the condition of permeability difference of 15 and low permeability core permeability of 300mD, water flooding to water cut of 98%, injection of 0.5PV system, and subsequent water flooding, The experimental results are shown in Figure 1 and Figure 2.

The experimental results show that for a single polymer microsphere system, polymer microsphere flooding and subsequent water flooding can increase the recovery rate of high-permeability cores by 18.6%, and improve the recovery rate of low-permeability cores by 18.5%; The core recovery rate is 16.3%, and the low-permeability core recovery rate is increased by 31.6%, which proves that the displacement performance in the formation with strong heterogeneity is obviously better than that of the polymer microsphere system.

The above-mentioned specific embodiments have been described in detail in conjunction with the accompanying drawings to the method of the present invention, but the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative and not restrictive. Those of ordinary skill in the art Under the enlightenment of the present invention, personnel can flexibly change the experimental conditions, analysis methods and objects as long as they do not exceed the gist of the present invention, and these all belong to the protection scope of the present invention.

Claims (5)

1. a kind of high temperature and high salt heterogeneous reservoir Double regulating displacement system, which is characterized in that by percentage to the quality, using including Following raw material is made:

A, oily phase: 40%~70%,

Oleic acid: 0.5%~2%,

B, water-soluble monomer:

Alkylolamides: 6%~8%,

Alkyl phenol polyoxyethylene ether sulfosalt surfactant: 1%~2%,

Acrylamide: 10%~20%,

Vinyl pyrrolidone: 1%~3%,

N, N '-methylene-bisacrylamide: the 0.1%~0.4% of water-soluble monomer gross mass,

C, initiator: the 0.01%~0.05% of water-soluble monomer gross mass,

D, remaining is deionized water；

Specific preparation process is as follows for the transfer drive system:

(1) aqueous phase solution is prepared: by acrylamide, vinyl pyrrolidone, N, N '-methylene-bisacrylamide, alkylol acyl Amine and alkyl alcohol ethoxylates sulfosalt surfactant are add to deionized water, stirring to solution clear；

(2) oil-phase solution is prepared: oleic acid being added in oily phase, is evenly stirred until solution clear；

(3) preparation of emulsion system: oil-phase solution is added to mechanical stirring, inert gas entrance/outlet three-necked flask In, under the stirring condition of 800r/min~1000r/min, aqueous phase solution is added drop-wise in oil-phase solution, time for adding is 30min starts to be passed through inert gas 30min after being added completely into so that emulsion system is in deoxygenation conditions, 200min~ Under the stirring condition of 400r/min, it is warming up to 45 DEG C~50 DEG C again after initiator is added, reaction 2h~3h to obtain the final product.

2. a kind of high temperature and high salt heterogeneous reservoir Double regulating displacement system according to claim 1, which is characterized in that described Initiator is azo-bis-isobutyrate hydrochloride, and the oil is mutually at least one of kerosene, white oil, diesel oil, the inert gas For one of helium, nitrogen or argon gas.

3. a kind of high temperature and high salt heterogeneous reservoir Double regulating displacement system according to claim 1, which is characterized in that described Alkylolamides skeleton symbol are as follows:

C_nH_2n+1CON(CH₂CH₂OH)₂

Wherein, n is 11~15.

4. a kind of high temperature and high salt heterogeneous reservoir Double regulating displacement system according to claim 1, which is characterized in that described The skeleton symbol of alkyl phenol polyoxyethylene ether sulfonate are as follows:

Wherein, it is 10~40 that m, which is 8~10, o,.

5. a kind of high temperature and high salt heterogeneous reservoir Double regulating displacement system according to any one of claims 1-4 is in high temperature and high salt Application in heterogeneous reservoir chemical flooding.