Polymer multistage variable frequency forced stretching system and oil displacement polymer preparation method

Abstract

The application discloses a polymer multistage variable frequency forced stretching system and an oil displacement polymer preparation method. The forced stretching system comprises a plurality of forced stretching units connected in series. The forced stretching unit comprises a rotating fixed grinding disc and a motor, and the motor controls the rotating speed of the rotating fixed grinding disc. The rotating fixed grinding disc is provided with an inlet and an outlet. The outlet of one rotating fixed grinding disc is connected with the inlet of the next rotating fixed grinding disc, so that the forced stretching units are connected in series. The outlet of the last forced stretching unit is connected with a discharge pump for external delivery. A polymer solution sampler is arranged at the outlet of each forced stretching unit. The motor is a variable frequency motor. According to the dissolving characteristics of different polymer solutions, the forced stretching strength and the stretching stages can be flexibly selected, the high-efficiency and uniform dissolving process of the difficult-to-dissolve polymer on the offshore platform is accelerated on the basis of meeting the viscosity retention rate, the further dispersion preparation of the polymer solution is ensured, and the efficiency of the polymer oil displacement preparation system on the offshore platform is improved.

Description

Technical Field

[0001] This invention relates to a polymer multi-stage variable frequency forced stretching system and a method for preparing oil displacement polymers, belonging to the field of petroleum engineering technology. Background Technology

[0002] Polymer flooding (FLD) is a common and effective chemical flooding technology used in tertiary oil recovery. This technology involves injecting polymer powder (such as polyacrylamide) into the oil reservoir after complete and homogenous hydrolysis to increase the oil recovery rate by expanding the swept area. Uniform dissolution of the polymer in water is a crucial step in FLD. To address the challenges of limited space on offshore platforms and the difficulty in hydrolyzing some hydrophobic functional polymers, tankless rapid dissolution systems are increasingly being applied to polymer formulation processes on offshore platforms. Compared to conventional dissolution processes, this rapid dissolution system eliminates the traditional curing tank and employs two modules—forced stretching and strong dispersion—to achieve rapid and uniform polymer dissolution. The forced stretching process is the core technology of this rapid dissolution system. The forced stretching system must consider the polymer's solubility, shear degradation, viscosity retention, post-stretch uniformity, and process time. Therefore, specific polymer stretching processes are required for different polymers. Summary of the Invention

[0003] The purpose of this invention is to provide a polymer multi-stage variable frequency forced stretching system that, when performing stretching processes on polymers for offshore platforms, ensures that different types of polymers can be stretched effectively, uniformly, and rapidly while meeting viscosity retention requirements, thereby optimizing polymer formulation efficiency and ensuring the smooth progress of subsequent strong dispersion processes of the polymer solution.

[0004] The polymer multi-stage variable frequency forced stretching system provided by the present invention includes several forced stretching units connected in series.

[0005] The forced stretching unit includes a rotating grinding disc and an electric motor, wherein the electric motor controls the rotational speed of the rotating grinding disc;

[0006] The rotating grinding disc is provided with an inlet and an outlet. The outlets on two connected rotating grinding discs are connected to the inlet, thereby realizing the series connection of the forced stretching unit.

[0007] The outlet of the forced stretching unit at the end is connected to a discharge pump for external discharge.

[0008] Preferably, the motor is a variable frequency motor to achieve control over the tensile strength.

[0009] Preferably, the electric motor controls the rotating grinding disc via a transmission shaft.

[0010] Preferably, the outlet of each of the forced stretching units is connected to the discharge pump via a bypass line;

[0011] The bypass pipeline is equipped with an electrically controlled valve to control the number of stretching stages.

[0012] Preferably, each of the forced stretching units is provided with a polymer solution sampler at its outlet for monitoring the performance of the polymer solution after forced stretching.

[0013] Preferably, the polymer solution sampler is an extraction and pressure-reducing sampler, which occupies a small area and has low shear stress on the polymer solution.

[0014] Preferably, the electric motor, the polymer solution sampler, and the electrically controlled valve are controlled by an electrical control cabinet.

[0015] Based on the aforementioned polymer multi-stage variable frequency forced stretching system, this invention provides a method for preparing an oil displacement polymer solution, comprising the following steps:

[0016] The oil displacement polymer and water are fed into the forced stretching unit of the forced stretching system according to the specified ratio. Stretching is performed under different tensile strengths and different stretching levels, and the viscosity of the oil displacement polymer solution after stretching is measured. By comparing the viscosity changes of the oil displacement polymer solution after stretching at different tensile strengths and different stretching levels, the stretching parameter that results in the largest increase in viscosity after two stretching operations is obtained. The oil displacement polymer solution is prepared under the specified stretching parameter.

[0017] The tensile parameters include the tensile strength and the tensile grade.

[0018] The tensile strength is 500–4000 rpm;

[0019] The tensile level is 1 to 2;

[0020] The oil displacement polymers include AP-P4, heavy oil activators, etc.

[0021] The polymer multi-stage variable frequency forced stretching system of this invention can flexibly select the forced stretching strength and stretching stage according to the dissolution characteristics of different polymer solutions. While meeting the viscosity retention rate, it accelerates the efficient and uniform dissolution process of poorly soluble polymers on offshore platforms, provides a guarantee for the further dispersion and preparation of polymer solutions, and improves the efficiency of the polymer flooding preparation system on offshore platforms. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the polymer multi-stage variable frequency forced stretching system of the present invention.

[0023] Figure 2This is a schematic diagram of the forced stretching unit in the polymer multi-stage variable frequency forced stretching system of the present invention.

[0024] The markings in the diagram are as follows:

[0025] 1, 2 Forced stretching unit, 101, 201 Inlet, 102, 202 Outlet, 103, 203 Rotary grinding disc, 104, 204 Drive shaft, 105, 205 Variable frequency motor, 3 Polymer solution sampler, 4 Discharge pump, 5 Electrical control cabinet, 6 Electrical control valve. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0027] like Figure 1 The polymer multi-stage variable frequency forced stretching system provided by the present invention includes two independent forced stretching units 1 and 2 (e.g., Figure 2 (As shown). Each independent stretching unit includes: a rotating and stationary grinding disc 103 (203), a drive shaft 104 (204), and a variable frequency motor 105 (205). The rotating and stationary grinding disc 103 (203) is provided with an inlet 101 (201) and an outlet 102 (202) connected by a flange. The polymer solution enters the grinding disc 103 through the inlet 101 for forced stretching, and is then discharged through the outlet 102. A polymer solution sampler 3 is provided at the outlet 102 for real-time monitoring of the stretching effect of the polymer solution. The motor 105 (205) controls the stretching speed through the drive shaft 104 (204) and adjusts the forced stretching strength through frequency conversion.

[0028] like Figure 1 As shown, two independent forced stretching units 1 and 2 are connected in series via pipelines to achieve two-stage forced stretching. A bypass pipeline and a matching electrically controlled valve 6 are also provided, and the number of forced stretching stages is controlled by opening and closing the electrically controlled valve 6. After the polymer solution completes forced stretching and meets the preparation requirements, it is transported by the discharge pump 4 to the subsequent forced dispersion device to complete the final preparation of the polymer solution.

[0029] like Figure 1 As shown, the frequency conversion of the motors of the forced stretching pump 4 and the discharge pump 4, as well as the switching of the electrically controlled valve 6 and the polymer sampler 3, are all uniformly controlled by the electrical control cabinet 5.

[0030] To investigate the effect of the polymer multi-stage variable frequency forced stretching system of the present invention on the forced stretching of polymer solutions, tensile tests were conducted on two polymers.

[0031] Experimental procedure:

[0032] Polymer powder and water are mixed according to their concentration ratio and fed into the forced stretching unit. The motor frequency and stretching stages of each stretching unit are controlled by an electrical control cabinet. A polymer solution sampling port is installed after each stretching unit to sample and measure the viscosity of the polymer solution after stretching. By comparing different tensile strengths (1000, 2000, 3000 rpm) and stretching stages (first stage, second stage), the optimal stretching parameters are determined to ensure the viscosity of the polymer solution.

[0033] Experimental results:

[0034] (1) Polymer AP-P4 (viscosity-average molecular weight approximately 1.06 × 10⁻⁶) 7 The viscosity values ​​after different levels and strengths of stretching are shown in Table 1.

[0035] Table 1. Forced stretching effect of AP-P4

[0036]

[0037] As shown in Table 1, for the AP-P4 type polymer, under medium tensile strength (2000 rpm), the polymer dissolves well after two stages of forced stretching, resulting in a higher solution viscosity. However, under high tensile strength (3000 rpm), the polymer molecular chains are sheared, leading to significant viscosity loss. Under low tensile strength (1000 rpm), the polymer solution is not fully dissolved. Therefore, the polymer reaches its highest viscosity value under medium tensile strength (2000 rpm) after two stages of stretching, indicating that the two-stage medium-strength forced stretching system accelerates the efficient and uniform dissolution process of the polymer solution.

[0038] (2) Polymer heavy oil activator (viscosity-average molecular weight approximately 2.81 × 10⁻⁶) 6 The viscosity values ​​after different levels and strengths of stretching are shown in Table 2.

[0039] Table 2. Forced Stretching Effect of Heavy Oil Activator

[0040]

[0041] As shown in Table 2, for heavy oil activators, under medium tensile strength (2000 rpm), the polymer dissolves well after two stages of forced stretching, resulting in a higher solution viscosity. However, compared to low tensile strength (1000 rpm), there is still some viscosity loss. When high tensile strength (3000 rpm) is used, the polymer molecular chains are sheared, leading to a greater viscosity loss. Therefore, the heavy oil activator can reach its highest viscosity value under low tensile strength (1000 rpm) after two stages of stretching.

Claims

1. A polymer multi-stage variable frequency forced stretching device, comprising a plurality of forced stretching units connected in series; The forced stretching unit includes a rotating grinding disc and an electric motor, wherein the electric motor controls the rotational speed of the rotating grinding disc; The rotating grinding disc is provided with an inlet and an outlet. The outlets on two connected rotating grinding discs are connected to the inlet, thereby realizing the series connection of the forced stretching unit. The outlet of the forced stretching unit at the end is connected to a discharge pump for external output; Each of the forced stretching units is equipped with a polymer solution sampler at its outlet; The electric motor is a variable frequency motor; The electric motor controls the rotating and stationary grinding discs via a transmission shaft; The outlet of each of the forced stretching units is connected to the discharge pump via a bypass line; The bypass pipeline is equipped with an electrically controlled valve; The electric motor, the polymer solution sampler, and the electrically controlled valve are controlled by an electrical control cabinet. The electric motor controls the stretching speed through the transmission shaft, and the forced tensile strength is adjusted through frequency conversion.

2. The forced tensioning device according to claim 1, characterized in that: The polymer solution sampler is an extraction and pressure-reducing sampler.

3. The application of the forced stretching device according to claim 1 or 2 in the preparation of oil displacement polymer solutions.

4. A method for preparing an oil displacement polymer solution, comprising the following steps: The oil displacement polymer and water are fed into the forced stretching unit of the forced stretching device according to the ratio described in claim 1 or 2. Stretching is performed under different tensile strengths and different stretching levels, and the viscosity of the oil displacement polymer solution after stretching is measured. The viscosity changes of the oil displacement polymer solution after stretching at different tensile strengths and different stretching levels are compared to obtain the stretching parameter that results in the largest increase in viscosity after two stretching operations. The oil displacement polymer solution is prepared under the stretching parameter. The tensile parameters include the tensile strength and the tensile grade.

5. The preparation method according to claim 4, characterized in that: The tensile strength is 500~4000 rpm; The tensile strength level is 1 to 2.

6. The preparation method according to claim 4 or 5, characterized in that: The oil displacement polymer includes AP-P4 or a heavy oil activator.

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