CN105349130B - It is suitable for the diutan and surfactant composite oil-displacing system of high temperature and high salt oil deposit - Google Patents

Abstract

The invention discloses a compound oil displacement system of diyou gum and a surfactant suitable for high-temperature and high-salt oil reservoirs, which is composed of the following components in mass percentage: 0.1%-0.5% of diyou gum and 0.05%-surfactant 0.6%, the rest is mineralized water. The invention also discloses a preparation method of the compound oil displacement system of Diyou gum and surfactant suitable for high-temperature and high-salt reservoirs. The steps include: taking each component according to the proportion, and mixing _NaCl , _CaCl Add in water and stir evenly to prepare mineralized water, then add surfactant and diuterene at normal temperature, stir evenly, and then get a composite oil displacement system of diuteramide and surfactant suitable for high-temperature and high-salt oil reservoirs. Diyou gum in the present invention has good compatibility with nonionic and zwitterionic surfactants, which can not only maintain the oil washing ability of the displacement fluid, but also greatly increase the swept volume, thereby improving the oil recovery rate .

Description

Diyou gum and surfactant composite flooding system suitable for high temperature and high salinity reservoirs

technical field

The invention relates to the field of oil field chemistry, in particular to a composite oil displacement system of Diyou gum and surfactant suitable for high-temperature and high-salt oil reservoirs.

Background technique

The exploitation of oil is divided into three stages: initially, it is exploited by relying on the natural energy of the formation, which is called primary oil recovery, and the general recovery rate is 5% to 10%; after the natural energy is exhausted, it can be continued by artificial water injection or gas injection , called secondary oil recovery, the recovery rate can be increased to 30% to 40%; after secondary oil recovery, there are still 60% to 70% of the remaining oil remaining in the ground, which can only be exploited by physical and chemical methods. For tertiary oil recovery. Tertiary oil recovery methods mainly include thermal flooding, miscible flooding, chemical flooding and microbial flooding.

Chemical flooding is a series of physical and chemical reactions between the chemical agent injected into the ground and the reservoir fluid, so that the oil can be displaced more effectively and the oil recovery rate can be improved. As early as the 1960s and 1970s, people began the laboratory research on chemical flooding EOR technology. Alkali flooding, active water flooding, polymer flooding and their developed binary and triple flooding systems have appeared successively. Alkaline ASP flooding system, that is, "polymer + surfactant + alkali", although it has achieved obvious effects in enhancing oil recovery, but due to the resources suitable for chemical flooding, more than 80% of the block strata The content of calcium and magnesium ions in the water is high, and the abundant calcium and magnesium combine with the alkali in ASP flooding to produce precipitation. Severe scaling has become a fatal injury to the popularization of ASP flooding technology. Gradually, people began to turn their attention to the research on the "polymer + surfactant" alkali-free binary compound flooding system. In the binary composite flooding system of surfactant and polymer, on the one hand, the polymer can expand the swept volume of the oil flooding system, and on the other hand, the surfactant can improve the oil displacement efficiency. If the two are well compatible, there will be broad application prospects for enhanced oil recovery. Hydrolyzed polyacrylamide (HPAM) has become an important polymer commonly used to increase the viscosity of the water phase. However, with the deepening of research, it was found that its temperature resistance and salt resistance are poor. Under high temperature and high salt conditions, the viscosity of the system The loss is serious, and during the underground migration process, the molecular chains will be broken due to the shear action of the underground channels, resulting in a decrease in the viscosity of the system. For this reason, some researchers have proposed to use hydrophobically modified polymers to improve the temperature and salt resistance of molecules, but due to the introduction of hydrophobic groups, it will be difficult to obtain products with a molecular weight as high as polyacrylamide, or to obtain high molecular weight products. Due to the introduction of a large number of hydrophobic groups, the water solubility of the molecule becomes poor. At the same time, hydrophobically associating polymers also have problems in compatibility with surfactants. With the development of oil fields, the reservoirs under harsh conditions such as high temperature and high salinity urgently need a suitable oil displacement system. Therefore, it is of great significance for the development of oil fields to develop a new polymer/surfactant binary flooding system with good compatibility, high temperature resistance and high salt.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art, and provide a compound oil displacement system of Diyou gum and surfactant suitable for high-temperature and high-salt reservoirs. Salt resistance properties.

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

A compound oil displacement system of diyou gum and surfactant suitable for high-temperature and high-salt oil reservoirs, consisting of the following components in mass percentage: 0.1%-0.5% of diyou gum, 0.05%-0.6% of surfactant, and the rest for mineralized water.

Preferably, the composite oil displacement system is composed of the following components in mass percentage: 0.15-0.2% diyout gum, 0.05-0.3% surfactant, and the rest is mineralized water.

Preferably, the surfactant is a mixture of an amphoteric surfactant and a nonionic surfactant, and the mass ratio is 75:25˜25:75.

Preferably, the mass ratio of the amphoteric surfactant to the nonionic surfactant is 50:50.

Preferably, the amphoteric surfactant active agent is lauryl polyoxyethylene ether betaine, dodecyl dimethyl hydroxypropyl sultaine, dodecyl betaine or dodecyl di One of the methyl betaines.

Preferably, the nonionic surfactant active agent is polyethylene glycol monooctyl phenyl ether (TX-100) or alkylphenol polyoxyethylene (10) ether (OP-10).

Preferably, the mineralized water is prepared from NaCl, CaCl ₂ and MgCl ₂ , the total salinity is 244121 mg·L ^-1 , and the concentrations of Na ⁺ , Mg ²⁺ , Ca ²⁺ and Cl ^- are respectively 95373 , 102, 411 and 148235 mg·L ^-1 ;

The present invention also discloses a preparation method of the compound oil displacement system of Diyou gum and surfactant suitable for high-temperature and high-salt reservoirs, the steps comprising:

Take each component according to the proportion, add NaCl, CaCl ₂ and MgCl ₂ into water at room temperature and stir evenly to prepare mineralized water, then add surfactant and diuterene at room temperature, and stir evenly to obtain a product suitable for high temperature and high salt Diyou gum and surfactant compound flooding system in oil reservoir.

According to the present invention, the diutan gum and surfactant compound oil displacement system suitable for high temperature and high salt reservoirs are applied in the tertiary oil recovery process of oil production.

The beneficial effects of the present invention are:

(1) The present invention selects Diyou gum to have a very good viscosifying effect, and its apparent viscosity is significantly higher than that of the xanthan gum system, higher than that of the HPAM system, and after compounding with surfactants, the salt-resistant effect is good . This is mainly because the main chain of Diutan gum is a sugar ring unit connected by -O- bonds, and each repeating unit on the molecular chain also contains a side chain with a length of two sugars, and the -COO- group is located in the In the repeating unit of the molecular main chain, there is no charged group in the side chain, so when the macromolecular chain of diuter gum is dissolved in surfactant and mineralized water, the molecular chain of diuter gum can be combined with surfactant Intertwined with each other, the side chains of Diutan gum will protect the main chain and the charged groups on the surfactant to a certain extent, so that Diutan gum molecules and surfactant molecules have a synergistic effect. Under low conditions, the oil displacement system can still maintain a certain viscosity, which greatly improves its salt tolerance. Although the xanthan gum molecule is also composed of the main chain and side chain of glycogen, its side chain contains two -COO- The group is more susceptible to the influence of salt, which greatly reduces its salt resistance.

(2) Under the condition of high temperature and high salt, the linear viscoelastic region of Diutan gum system is very obvious, and its viscoelasticity is obviously stronger than that of xanthan gum and HPAM. From the perspective of the structure of Diutan Gum, there are a large number of -OH and a certain number of -COO- groups on its molecular chain. Such a hydrophilic group structure has good compatibility with nonionic and zwitterionic surfactants. .

(3) There is a synergistic effect between diyou gum and the surfactant compound system used, and the compounding of the two can produce an effect better than that of the two single systems. The low interfacial tension makes Diyou gum/surfactant binary system not only maintain the oil washing ability of the displacement fluid, but also greatly increase its swept volume during the oil displacement process, thereby improving oil recovery .

Description of drawings

Fig. 1 is the molecular structure diagram of diyout gum;

Figure 2 is a graph showing the variation of viscosity of 0.175% polymer solution with shear rate under the condition of salinity of 244121 mg·L ^-1 and temperature of 25 and 90°C respectively; in the figure diutan gum, xanthan gum and HPAM are designated respectively Eucalyptus, xanthan gum and partially hydrolyzed polyacrylamide;

Fig. 3 is the composite modulus of 0.175% polymer solution system with a salinity of 244121 mg·L ^-1 at 90°C (Fig. A), storage modulus G′ and loss modulus G″ (Fig. B) with stress change map;

Figure 4 shows the apparent ^viscosity (A) and shear stress ( B) Variation graph with shear rate;

Figure 5 is a composite model of the solution of the 0.15% polymer/0.05% dodecyldimethylhydroxypropyl sulfobetaine/0.05% TX-100 composite system with a salinity of 244121mg·L ^-1 and 90°C The change diagram of the quantity with the stress (figure A) and the change diagram of the storage modulus G' and the loss modulus G" with the oscillation frequency (figure B);

Figure 6 shows the interfacial tension of the 0.175% polymer/0.1% dodecyl dimethyl betaine/0.1% OP-10 composite system with a salinity of 244121 mg·L ^-1 at 90°C with the concentration of surfactant change map;

Fig. 7 shows the cumulative recovery of the composite system of 0.175% polymer/0.15% polyoxyethylene lauryl ether betaine/0.15% TX-100 at 90°C with a salinity of 244121 mg·L ^-1 Change graph of PV number.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The surfactants used in this example are all commercially available products, and the purity level of the products is chemically pure; the diyout gum used is provided by CPK Company of the United States, with a purity of 98% and a molecular weight of 5.2×10 ⁶ g·mol ^{- 1} , the intrinsic viscosity is 5450mL·g ^-1 . The crude oil sample used in the indoor simulated oil displacement experiment is ordinary heavy oil from Henan Oilfield, with an acid value of 1.361 mgKOH/g and a viscosity of 254 mPas.

Example 1

A compound oil displacement system of Diutan gum and surfactant suitable for high-temperature and high-salt oil reservoirs. Hydroxypropyl sulfobetaine accounts for 0.05%, TX-100 accounts for 0.05%, and the rest is mineralized water. The mineralized water is formulated from NaCl, CaCl ₂ and MgCl ₂ , and the total mineralization degree is 244121mg·L ^-1 , where the concentrations of Na ⁺ , Mg ²⁺ , Ca ²⁺ and Cl ^- are 95373, 102, 411 and 148235 mg·L ^-1 , respectively.

The preparation method is as follows: add NaCl, CaCl ₂ and MgCl ₂ into water at normal temperature and stir to prepare mineralized water, then add 0.05g of dodecyl dimethyl hydroxypropyl sulfobetaine, 0.05g of Add TX-100 and 0.15g of Diutan gum into 99.75g of mineralized water, and stir evenly to obtain a combined oil displacement system of Diutan gum and surfactant suitable for high-temperature and high-salt reservoirs.

In the laboratory simulation oil displacement experiment, after water flooding until the sand-packed pipe does not produce oil, the system is used for further oil displacement experiments. When the injection volume of the system is 0.5PV, the recovery rate can be increased by 36.8% on the basis of water flooding .

Example 2

A compound oil displacement system of Diutan gum and surfactant suitable for high-temperature and high-salt oil reservoirs, which is composed of the following components in mass percentage: 0.2% Diutan gum, 0.3% surfactant, wherein dodecyl polyoxygen Vinyl ether betaine accounts for 0.15%, TX-100 accounts for 0.15%, and the rest is mineralized water. The mineralized water is prepared from NaCl, CaCl ₂ and MgCl _2. The total mineralization degree is 244121mg·L ^-1 , of which The concentrations of Na ⁺ , Mg ²⁺ , Ca ²⁺ and Cl ^- were 95373, 102, 411 and 148235 mg·L ^-1 , respectively.

The preparation method is as follows: add NaCl, CaCl ₂ and MgCl ₂ into water at normal temperature and stir to prepare mineralized water, then add 0.15g of lauryl polyoxyethylene ether betaine, 0.15g of TX-100 and Add 0.2g of Diyou gum to 99.5g of mineralized water, and stir evenly to obtain a composite oil displacement system of Diyou gum and surfactant suitable for high-temperature and high-salt oil reservoirs.

In the laboratory simulation oil displacement experiment, after water flooding until the sand-packed pipe does not produce oil, the system is used for further oil displacement experiments. When the injection volume of the system is 0.5PV, the recovery rate can be increased by 44.2% on the basis of water flooding .

Example 3

A compound oil displacement system of Diyou gum and surfactant suitable for high-temperature and high-salt oil reservoirs, which is composed of the following components in mass percentage: 0.175% of Diyou gum, 0.2% of surfactant, and dodecyl dimethyl Betaine-based betaine accounts for 0.1%, OP-10 accounts for 0.1%, and the rest is mineralized water. The mineralized water is prepared from NaCl, CaCl ₂ and MgCl _2. The total mineralization degree is 244121mg·L ^-1 , of which Na The concentrations of ⁺ , Mg ²⁺ , Ca ²⁺ and Cl ^- were 95373, 102, 411 and 148235 mg·L ^-1 , respectively.

The preparation method is as follows: add NaCl, CaCl ₂ and MgCl ₂ into water at normal temperature and stir to prepare mineralized water, then add 0.1g of dodecyl dimethyl betaine, 0.1g of OP-10 and 0.175 Add 99.625g of Diyou gum into 99.625g of mineralized water, and stir evenly to obtain the Diyou gum and surfactant composite flooding system suitable for high-temperature and high-salt oil reservoirs.

In the laboratory simulation oil displacement experiment, after water flooding until the sand-packed pipe does not produce oil, the system is used for further oil displacement experiments. When the injection volume of the system is 0.5PV, the recovery rate can be increased by 37.2% on the basis of water flooding .

Example 4

A compound oil displacement system of Diyou gum and surfactant suitable for high-temperature and high-salt oil reservoirs, which consists of the following components in mass percentage: 0.5% Diyou gum, 0.5% surfactant, wherein Accounted for 0.3%, OP-10 accounted for 0.2%, the rest is mineralized water, the mineralized water is prepared from NaCl, CaCl ₂ and MgCl ₂ , the total salinity is 244121mg·L ^-1 , of which Na ⁺ , Mg The concentrations of ²⁺ , Ca ²⁺ and Cl ^- were 95373, 102, 411 and 148235 mg·L ^-1 , respectively.

The preparation method is as follows: add NaCl, CaCl ₂ and MgCl ₂ into water at normal temperature and stir to prepare mineralized water, then add 0.3g of dodecyl betaine, 0.2g of OP-10 and 0.5g of fixed Diyou gum was added to 99g of mineralized water and stirred evenly to obtain a combined oil displacement system of diyou gum and surfactant suitable for high-temperature and high-salt oil reservoirs.

In the laboratory simulation oil displacement experiment, after water flooding until the sand-packed pipe does not produce oil, the system is used for further oil displacement experiments. When the injection volume of the system is 0.5PV, the recovery rate can be increased by 34.7% based on water flooding .

As shown in Figure 2, Diutan gum has a very good viscosity-increasing effect. When the temperature is 25°C and the shear rate is 7s ^-1 , the apparent viscosity of Diuter gum is equivalent to that of HPAM commonly used in oilfields, which is significantly higher than that of yellow rubber. The viscosity of raw gum, and when the temperature rises to 90 ℃, the apparent viscosity of diutan gum system is obviously higher than that of xanthan gum system, higher than that of HPAM system. This result fully shows that the viscosifying effect of the bio-glue system is obviously stronger than that of the HPAM system, and the effect of Diyou gum is also better than that of xanthan gum. This is mainly because the main chain of Diutan gum is a sugar ring unit connected by -O- bonds, and each repeating unit on the molecular chain also contains a side chain with a length of two sugar elements, and the repeating unit of the main chain of the molecule , contains a -COO- group, and there is no charged group in the side chain, so when the macromolecular chain of Diutan Gum is dissolved in the surfactant and mineralized water, the molecular chain and the surfactant are intertwined, The side chain will protect the charged groups on the main chain to a certain extent. At a temperature higher than 90°C, the drive system can still maintain a certain viscosity, which greatly improves its salt resistance. Xanthan gum molecules Although it is also composed of the main chain and side chain of glycogen, its side chain contains two -COO- groups, which are more susceptible to the influence of salt, which greatly reduces its salt tolerance.

As shown in Figure 3, under the condition of high temperature and high salt, the linear viscoelastic zone of Diyou gum system is very obvious, and its viscoelasticity is obviously stronger than that of xanthan gum and HPAM, which shows that Diyou gum has very good temperature resistance Salt resistance, under high temperature and high salt conditions, still has very obvious viscoelasticity, which is a very important property for oil displacement systems. From the perspective of the structure of Diutan Gum, there are a large number of -OH and a certain number of -COO- groups on its molecular chain. Such a hydrophilic group structure has good compatibility with nonionic and zwitterionic surfactants. .

As shown in Figure 4 and Figure 5, after Diutan gum is compounded with amphoteric and non-ionic surfactants, the system still has the temperature and salt resistance performance of Diutan gum system, showing strong viscoelastic properties.

As shown in Figure 6, when Diyou gum is compounded with surfactants, when the concentration of surfactants is 0.1% to 0.3%, the interfacial tension of the composite system is the lowest, reaching the order of 10 ^-2 mN·m ^-1 , although it has not reached 10 ^-3 to 10 ^-4 is an ultra-low order of magnitude, but it is not easy to achieve such a low interfacial tension at a high temperature of 90°C and a salinity of 244121mg·L ^-1 .

Figure 7 shows the variation of the recovery factor of different oil displacement systems with the injected PV number. The crude oil is ordinary heavy oil in Henan Oilfield, the acid value of the crude oil is 1.361mgKOH/g, and the viscosity is 254mPas. In the composite flooding system, the recovery factor of diutan gum/surfactant system is also higher than that of xanthan gum/surfactant system and HPAM/surfactant system. This is mainly because the dipitan gum/surfactant system has the highest viscosity among the investigated systems, which can effectively increase the swept volume of the displacement fluid during the oil displacement process, reduce residual oil in the pores to a greater extent, and improve oil recovery. yield. Under high-temperature and high-salt conditions, the diutan gum/surfactant system still has a high oil recovery, which is mainly due to the synergistic effect between the diutan gum and the surfactant compound system used. The combination of the two can It produces an effect better than that of the two single systems, that is, while maintaining a high viscosity of the system, it also maintains a low interfacial tension of the surfactant, so that the dipitan gum/surfactant system can maintain both The oil washing ability of the displacement fluid can greatly increase its swept volume, thereby enhancing the oil recovery rate.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be described in the foregoing embodiments Modifications are made to the recorded technical solutions, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (4)

1. a kind of diutan for being suitable for high temperature and high salt oil deposit and surfactant composite oil-displacing system, it is characterized in that, by following The component composition of mass percent：Diutan 0.1%-0.5%, surfactant 0.05%-0.6%, remaining is mineralized water；Table Face activating agent is amphoteric surfactant and nonionic surface active agent mass ratio is 75:25~25:75 mixture；Both sexes Surfactant activity agent is alkylpolyoxyethylene glycine betaine, dodecyl dimethyl hydroxypropyl sulfobetaines, ten One kind in dialkyl group glycine betaine or dodecyldimethylammonium hydroxide inner salt；Nonionic surfactant activating agent is polyethyleneglycol Octyl phenyl ether or alkylphenol-polyethenoxy (10) ether；Mineralized water is by NaCl, CaCl₂And MgCl₂It is formulated, total salinity is 244121mg·L^-1, wherein Na⁺、Mg²⁺、Ca²⁺And Cl^-Concentration be respectively 95373,102,411 and 148235mgL^-1。

2. a kind of diutan for being suitable for high temperature and high salt oil deposit as claimed in claim 1 and surfactant combination flooding oil body System, it is characterized in that, it is made up of the component of following mass percent：Diutan 0.15~0.2%, surfactant 0.05~ 0.3%, remaining is mineralized water.

3. a kind of diutan for being suitable for high temperature and high salt oil deposit as claimed in claim 1 and surfactant composite oil-displacing system Preparation method, it is characterized in that, step is as follows：Each component is taken by proportioning, by NaCl, CaCl under normal temperature₂And MgCl₂It is added to the water Stir and be prepared into mineralized water, then add surfactant and diutan at normal temperatures, stir, produce and be suitable for height The diutan and surfactant composite oil-displacing system of warm high salinity reservoir.

4. the diutan for being suitable for high temperature and high salt oil deposit and surfactant complex oil displacing as described in claim any one of 1-2 Application of the system during the tertiary oil recovery of oil exploitation.