Radiation Preparation and Performance of Compound Polymer Profile Control Agent

Fund Project: Key Project of Heilongjiang Academy of Sciences (01CFBALYG05).

Compound polymer profile control agent (FRC) is a kind of macromolecule water-absorbing material for oilfield profile control and water shutoff. Because its structure contains organic-organic components, it is compounded with conventional organic monomer homopolymer materials. The organic-inorganic hybrid composite structure of the polymer water-absorbent material and the good interfacial bonding between the substrates exhibit more excellent salt-resistance, heat-resistance, and shear-resistance comprehensive properties.

The most important application performance of FRC is the volume expansion capacity (ie, the expansion factor). Its swelling performance depends on the composition of the material and its fine cross-linked structure, but also depends on the environmental factors of the external medium. The effects of synthetic process conditions on material properties and on-site application simulations are discussed.

2.1 Effect of Crosslinker Concentration on Water Absorption of FRC FRC is a low cross-link density, water-absorbent, expandable polymer material.

According to Huggins' theory, the main factor affecting water swelling is the cross-linking density of the material and the hydrophilic groups contained in the material structure. By regulating the concentration of the cross-linking agent, the density of cross-linking points in the polymer network can be changed, thereby changing the size of the water-absorbing network and achieving the purpose of controlling the water-absorbing multiple. If the concentration of the cross-linking agent is too high, the cross-linking density of the polymer is too large, the network chain between the cross-linking points becomes shorter, the pore volume in the network structure is too small, and the water-absorbing multiple decreases. If the cross-linking agent concentration is too low, the polymer chains cannot be cross-linked to form a three-dimensional network structure. The cross-linking density of the polymer is too small, the gel strength is poor, and the macroscopically water-soluble property shows that the material does not have use properties. The range of cross-linking agent concentration is appropriate (see).

2.2 Effect of montmorillonite mass fraction on the water absorption of FRC The mass fraction of montmorillonite has a great influence on the water absorption performance of FRC. The main component of montmorillonite is aluminosilicate, which has a multi-functional layered sheet structure. The body is embedded and polymerized to a certain extent, it has the function of a cross-linking agent. It and the chemical crosslinking agent and radiation-induced cross-linking synergistically promote the increase of the cross-linking density of the composite material, thereby affecting the effect of the cross-linking agent concentration on the water absorption multiple of the FRC. The water absorption properties. The effect of montmorillonite mass fraction on the water absorption (see), when the mass fraction of montmorillonite is below 15%, FRC has a higher water absorption. And when the mass fraction of montmorillonite is less than 5%, the water-absorbing multiple of FRC is higher than that of pure organic monomer copolymer. This is a function that montmorillonite, as an embedded acceptor of an organic monomer, has a cross-linking point in the course of polymerization, and proper addition of a certain concentration of montmorillonite contributes to the formation of a cross-linked structure of the material. When the amount of montmorillonite added is too large, the proportion of embedded organic monomers is relatively reduced, and montmorillonite fills most of the space of the cross-linked network structure space, hinders the absorption of water molecules, and reduces the water-absorbing multiple of the material.

Effect of montmorillonite mass fraction on water absorption capacity of FRC Composites partially filled with montmorillonite were compared with pure organic monomer copolymers under the conditions of the same cross-linking agent concentration and irradiation conditions (see Table 1). . When the mass fraction of montmorillonite is less than 5%, the water-absorbing multiple of FRC is higher than that of pure polymer.

Table 1 Effect of montmorillonite mass fraction on the water absorption of FRC The cross-linker (N+N) concentration absorbs water. Fold / (gg Montmorillonite mass fraction montmorillonite mass fraction (0%) 2.3 Degree of hydrolysis on the FRC water absorption multiple - COONa groups of different hydrophilicity, the use of adjusting the proportion of acrylamide and sodium acrylate monomer, F-RCl with different degrees of hydrolysis can be prepared! The degree of water absorption of FRC reaches the highest when both propylene and acrylamide account for 70% of the total amount of mixed monomer of acrylamide and sodium acrylate (see below), and the degree of hydrolysis is higher or lower than 70. At %, the water-absorption multiples are all reduced because on the one hand, a COONa is more polar and more hydrophilic than a CONH2, and as the degree of hydrolysis increases, the content of a COONa group in the material structure increases, which is beneficial to the material. Increased water absorption; but on the other hand, a COONa is an ionizable ionic group that dissociates to a COO in aqueous solution and the degree of Na+ hydrolysis is too high due to the electrostatic repulsion of a COO on the polymer chain. , making the cross-linking network system unstable, the material's water absorption capacity decreased.

Effect of Degree of Hydrolysis on Water Absorption of FRC In summary, by controlling the degree of hydrolysis, both the proportion of acrylamide and sodium acrylate in the comonomer component can be adjusted, and the ratio of a COONa and a CONH2 group in the material structure can be adjusted to make the electricity The molecular group-CONH2 (small electrostatic repulsion between groups) and the COONa ionic group (larger electrostatic interaction between groups) are arranged rationally on the polymer chain. The synergistic effect of each group makes the FRC The water absorption performance is higher than that of montmorillonite-acrylamide and montmorillonite-sodium acrylate polymers.

2.4 Effect of radiation dose rate on the water absorption multiple of FRC The radiation dose rate will affect the size of molecular chains between crosslinks. In the case of a certain concentration of cross-linking agent, the size of the molecular chain will directly affect the size of the cross-linked network, thus affecting the water absorption capacity of the FRC. Effect of Dose Rate on Water Absorption (see), the FRC's water-absorbing multiple starts to increase with the increase of the dosage rate, and after 2.5 Gy/min, the water-absorbing power decreases. This is because when the dose rate is too low, the generated free radical concentration is low, the monomer-induced reaction rate is low, the overall reaction rate is very slow, the organic monomer and montmorillonite cannot be effectively embedded in the polymerization, and the composite polymer is difficult to form; If the dose rate is too high, it is easy to explode, and the organic monomer precipitates as a polymerization center to form a homopolymer, and the crosslink density is too high, and the water absorption ratio is lowered.

2.5 Effect of Irradiation Dose on Water Absorption of FRC In radiation polymerization, the radiation dose is proportional to the irradiation time under the condition of dose rate determination. Although prolonging the irradiation time and increasing the radiation dose can increase the conversion rate of the monomer, the irradiation time is too long and the radiation dose is too large. As the radiation crosslinking increases the cross-link density, the network density decreases. Smaller, lower water absorption.

The effect of irradiation dose on the water absorption multiple (see Table 2) irradiation dose of 10 ~ 25kGy is appropriate.

Table 2 Effect of Radiation Dosage on Water Absorption of FRC Radiation Rate Dose/(g'g-1) Relation between Montmorillonite 2.6 Particle Size and Water Absorption Rate ~ 30 mesh and 80 to 100 mesh FRC samples were measured for water absorption rate. Samples of 80 to 100 mesh can be saturated with water in 15 minutes, while samples of 20 to 30 mesh require about 65 minutes to reach saturation. This is because the water absorption rate is determined by the radial diffusion rate of water molecules from the surface of the material particles to its interior. The smaller the particle size, the larger the specific surface area, the shorter the water molecule's diffusion path to the interior and the faster the water absorption rate, and vice versa. .

2.7 water retention performance test ~ 100 mesh, saturated water swelling, placed in a centrifuge, speed 4000r/min, the sample's water retention rate in the centrifuge experiment changes little, indicating that the material under pressure water retention performance.

2.8 Friction and migration characteristics of FRC gel particles in porous media 2.8.1 Influence of core permeability on gel plugging 007md core, pump displacement 2 mL/min, reverse injection blocking agent 1/3 after oil flooding The void volume is then positively displaced with water. With the increase of injection volume, the lower the permeability of the core, the smaller the outlet flow (see) 2.8.2 FRC Gel Particle Flowability Test To evaluate the sealing and transport of FRC gel particles by detecting the pressure changes at different injection stages. Move effect. The first stage is to adjust the front waterflood, the pressure remains basically stable; the second stage is to note the FRC grain stage, the general trend is that the pressure keeps rising, but there is a large fluctuation, and the fluctuation is the migration of particles in the pores and throats. 2.9 The FRC gel particles were used to control the performance of the gel particles. The sand cores were used to measure the gel particles. Before the experiment, the cores were saturated with oil and then water flooded. When the water flooded to a water content of 98%, the injection concentration was 1 again. 000mg/L FRC particles were subjected to displacement test (see Table 3). Table 3 Comparison of water flooding and FRC gel displacement performance Core number No. of gel floods produced after water flooding after flooding/% recovery degree/ % Increment/% results show that the use of gel particle displacement can significantly reduce the residual oil saturation and increase recovery.

3 conclusions.

:Pellet is optimized from liyan; LiS is regulated by structural parameters to regulate the initial swelling speed of FRC, and 5t is prepared by radiation-induced polymerization to prepare composite polymer profile control agent (FRC) and the main technical parameters in the synthesis process such as raw material selection and The group distribution ratio, radiation polymerization conditions, and additive concentration profile control agent swelling rate can be controlled within 10 ~ 180min, which can realize the change from high pressure pumping to normal pressure injection mode in the oilfield. The FRC and water-soluble polyacrylamide have good compounding performance and can significantly increase the oil recovery. The research conclusions can also provide theoretical basis and technical guarantee for the large-scale production of FRC.