A chemical flooding online continuous preparation and adjustment device and method

Abstract

The present invention discloses an online continuous preparation and adjustment device and method for chemical drive. The online continuous preparation and adjustment device for chemical drive includes a polymer forced stretching system, a cross-linking mixing system and a polymer strong dispersion system; the cross-linking mixing system includes a first-order cross-linking mixing tube, a venturi tube and a second-order cross-linking mixing tube connected in sequence; an SD-type spiral plate is provided in the first-order AC mixing tube to make the polymer fluid generate a spiral flow and be evenly dispersed; the venturi tube is provided with a cross-linking agent injection port; the second-order cross-linking mixing tube is provided with an SK-type spiral plate and an SD-type spiral plate to accelerate the mixing of the polymer and the cross-linking agent by creating a spiral flow and turbulence. The present invention adopts an online dissolution process, eliminates the maturation tank, and adopts a two-stage cross-linking mixing tube and a venturi tube for mixing, thereby ensuring that the system is evenly dispersed and improving the maturation efficiency.

Description

Technical Field

[0001] The present invention relates to an online continuous chemical flooding preparation and control device and method, belonging to the technical field of profile control and water blocking in offshore oilfield development. Background Art

[0002] Some offshore high-temperature, high-salinity oilfields have high formation temperatures and high formation water salinity, making profile control difficult. The structure of profile control agents is easily altered and unevenly dispersed, leading to agglomeration and ineffective subsequent chemical flooding. Furthermore, offshore platforms are small and have limited capacity. The transportation, lifting, installation, and maintenance of large equipment are restricted, and the space available for surface injection equipment is very limited. Therefore, it is necessary to explore online continuous fluid dispensing technologies that combine oil flooding and profile control capabilities, and develop an offshore polymer rapid dissolution and online flooding process system to address the challenges of chemical flooding and profile control on offshore platforms while also achieving high temperature and high salinity conditions.

[0003] Currently, profile control and flooding control utilizes air-delivered dry powder mixed with incoming water through a water-powder mixer. This powder is initially dissolved in a dissolution tank, then transferred by a transfer pump to a maturation tank for maturation before being injected into the wellhead with an injection pump. This process involves two maturation tanks being emptied, requiring only intermittent preparation, not continuous liquid production. Furthermore, the maximum polymer concentration is limited to 6000 ppm, limiting the ability to achieve high-concentration preparations. Another online profile control and flooding control process utilizes an emulsion polymer pumped through a metering plunger pump, then injected into a pipeline and mixed with other additives before being injected into the well. The main drawbacks of this process are the high cost of the emulsion polymer and the inability to maintain a high influent viscosity due to the low effective content of the emulsion polymer. Therefore, improvements are needed to existing online profile control equipment. Summary of the Invention

[0004] The purpose of the present invention is to provide a novel online continuous preparation and profile control device, which is comprehensively optimized in terms of space and adaptability, and realizes the online preparation of high-concentration dry powder polymer solutions. It solves the problems of the special structure and available space limitations of the oil production platform during the tertiary oil recovery development and application of offshore heavy oil fields, as well as the drawbacks of the previous single online equipment system.

[0005] The chemical flooding online continuous preparation and adjustment device provided by the present invention comprises a polymer forced stretching system, a cross-linking mixing system and a polymer strong dispersion system;

[0006] The cross-linking mixing system comprises a first-stage cross-linking mixing tube, a venturi tube, and a second-stage cross-linking mixing tube connected in sequence; the first-stage AC mixing tube is provided with an SD-type spiral plate to generate a spiral flow and uniform dispersion of the polymer fluid; the venturi tube is provided with a cross-linking agent injection port; the second-stage cross-linking mixing tube is provided with an SK-type spiral plate and an SD-type spiral plate connected in sequence to accelerate the mixing of the polymer and the cross-linking agent by generating a spiral flow and turbulence;

[0007] The inlet of the first-order cross-linking mixing tube is connected to the outlet of the polymer forced stretching system;

[0008] The outlet of the second-stage cross-linking mixing tube is connected to the inlet of the polymer strong dispersion system.

[0009] Preferably, the SD-type spiral plates and the SK-type spiral plates are evenly staggered.

[0010] Preferably, the polymer forced stretching system includes a multi-stage gear disc to achieve forced stretching, rapid atomization and hydration swelling of the polymer, avoiding the generation of "fish eyes" during the swelling process.

[0011] Preferably, the polymer strong dispersion system includes a rotating packing bed, which provides the forced stretched polymer suspension with instantaneous high shear conditions through the porous channels provided by the high-speed rotating material, so that the diffusion rate of water molecules penetrating into the polymer swollen particles into its chain segments is instantaneously accelerated, thereby increasing the dissolution rate.

[0012] The present invention further provides a method for online preparation of chemical flooding profile control fluid using the chemical flooding online continuous preparation and control device, comprising the following steps:

[0013] S1, inputting the polymer dry powder into the polymer forced stretching system in the chemical flooding online continuous preparation and adjustment device for stretching pretreatment to obtain a polymer solution;

[0014] S2, the polymer solution is pre-dispersed through the SD-type spiral plate in the first-order cross-linking mixing tube in the cross-linking mixing system; the liquid cross-linking agent is injected through the cross-linking agent injection port on the venturi tube, and the negative pressure generated by the venturi tube is conducive to the injection of the cross-linking agent;

[0015] S3, the polymer solution and the liquid crosslinking agent enter the second-stage crosslinking mixing tube for secondary mixing and dispersion to ensure uniform dispersion of the system;

[0016] S4. The mixed and dispersed solution enters the polymer strong dispersion system for cross-linking and mixing again, thereby completing the online preparation of the profile control agent.

[0017] The device of the present invention has higher adaptability to working conditions, larger processing capacity and safety in use, and can realize continuous online preparation of high-concentration solutions. The polymer concentration can reach up to 6000 mg / L, and the equipment processing capacity meets 10m 3 / h, and at the same time, the maturation tank is eliminated and it can be directly put into the well, which can effectively reduce the transportation cost and chemical cost.

[0018] Each system in the device of the present invention forms a module and is installed in its own skid, which meets the needs of online preparation of high-concentration dry powder polymer solutions within the special spatial structure of offshore oil platforms, fully realizes the integration, intelligence and versatility of the equipment, and overcomes the design bottleneck of the currently used injection system.

[0019] The present invention adopts an online dissolution process, eliminates a maturation tank, and adopts a two-stage cross-linking mixing tube and a venturi tube for mixing, thereby ensuring uniform dispersion of the system and improving maturation efficiency.

[0020] The present invention comprises a polymer forced stretching system, a cross-linking mixing system and a polymer strong dispersion system to form an online control and drive device. The three systems are each skid-mounted and can be used independently. The polymer forced stretching system and the strong dispersion system can realize a polymer instant process device. When the three systems work together, they form a multifunctional integrated control and drive chemical instant preparation process system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a structural schematic diagram of the cross-linking mixing system in the online continuous preparation and adjustment device for chemical flooding of the present invention.

[0022] Figure 2 This is a structural diagram of the on-line continuous preparation and adjustment device for chemical flooding of the present invention.

[0023] Figure 3 This is a cross-sectional view of the SK-type spiral plate in the online continuous preparation and adjustment device for chemical flooding of the present invention.

[0024] The marks in the figure are as follows:

[0025] 1. First-order cross-linked mixing tube; 1. 1SD type spiral plate; 2. Venturi tube; 3. Second-order cross-linked mixing tube; 3. 1SK type spiral plate; 3. 2SD type spiral plate. DETAILED DESCRIPTION

[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 As shown, the chemical flooding online continuous preparation and adjustment device provided by the present invention includes a polymer forced stretching system, a cross-linking mixing system and a polymer strong dispersion system connected in sequence. Among them, the structure of the cross-linking mixing system is as follows Figure 2 As shown, it includes a first-stage cross-linking mixer 1, a venturi tube 2 and a second-stage cross-linking mixing tube 3.

[0028] like Figure 1As shown, the polymer solution is stretched through the polymer forced stretching system and then enters the cross-linking mixing system. The polymer forced stretching system uses different types of forced stretching toothed discs to achieve forced stretching, rapid atomization, and hydration swelling of the polymer, avoiding the formation of "fish eyes" during the swelling process.

[0029] like Figure 2 As shown, the cross-linking mixing system includes a first-stage cross-linking mixing tube 1, a venturi tube 2, and a second-stage cross-linking mixing tube 3 connected in sequence. Among them, the first-stage AC mixing tube 1 is provided with uniformly staggered SD-type spiral plates 1-1 to make the polymer fluid generate spiral flow and disperse evenly. The venturi tube 2 is provided with a cross-linking agent injection port. The second-stage cross-linking mixing tube 3 is provided with uniformly staggered SK-type spiral plates 3-1 (such as Figure 3 The inlet of the first-stage crosslinking mixing tube 1 is connected to the outlet of the polymer forced stretching system, while the outlet of the second-stage crosslinking mixing tube 3 is connected to the inlet of the polymer strong dispersion system.

[0030] like Figure 2 As shown, the outlet of the cross-linking mixing system is connected to the strong dispersion system. A rotating packing bed is provided in the strong dispersion system. The porous channels provided by the high-speed rotation of the rotating packing bed provide instantaneous conditions of high shear force for the forced stretched polymer suspension, which instantly accelerates the diffusion rate of water molecules in the polymer swollen particles into their chain segments, thereby increasing the dissolution rate.

[0031] The online continuous chemical flooding preparation and control device of the present invention is used to prepare the polymer solution and the liquid cross-linking agent online:

[0032] The polymer used is AP-P4 (viscosity average molecular weight is about 1.06×10 7 ), the cross-linking agent is aluminum citrate.

[0033] (1) The polymer solution enters the polymer forced stretching system for stretching pretreatment, the mother liquor concentration is 6000 mg / L, and the processing volume is 10m 3 / h.

[0034] (2) The polymer solution after forced stretching is pre-dispersed through the first-stage crosslinking mixing tube 1. At the same time, a liquid crosslinking agent is introduced through the injection port on the venturi tube 2 and mixed with the polymer solution in the second-stage crosslinking mixing tube 3. The concentration of the liquid crosslinking agent is 2000 mg / L.

[0035] (3) The mixed and dispersed solution enters the strong dispersion system, where the shear force generated by the rotating packed bed is used to achieve thorough and complete mixing. The rotating packed bed speed is set at 300 rpm.

[0036] (4) The thoroughly dispersed profile control agent is sampled and tested to test the gelling strength and viscoelastic modulus of the profile control agent and compare them with the profile control agent prepared by conventional methods.

[0037] The conventional preparation method is: prepare a polymer solution with a concentration of 6000 mg / L and a cross-linking agent with a concentration of 2000 mg / L respectively; and mix the two uniformly with a stirrer (rotation speed is 400 rpm).

[0038] The results are shown in Table 1. It can be seen that the effect of the profile control agent prepared by the chemical flooding online continuous preparation device is very close to that of the conventional method; however, the online preparation method of the present invention shortens the preparation time from 1 hour to less than 2 minutes, greatly shortening the preparation time.

[0039] Table 1 Comparison of test results

[0040]

Claims

1. A chemical flooding online continuous preparation and adjustment device, including a polymer forced stretching system, a cross-linking mixing system and a polymer strong dispersion system; The cross-linking mixing system comprises a first-stage cross-linking mixing tube, a venturi tube, and a second-stage cross-linking mixing tube connected in sequence; the first-stage cross-linking mixing tube is provided with an SD-type spiral plate to generate a spiral flow and uniform dispersion of the polymer fluid; the venturi tube is provided with a cross-linking agent injection port; the second-stage cross-linking mixing tube is provided with an SK-type spiral plate and an SD-type spiral plate connected in sequence to accelerate mixing of the polymer and the cross-linking agent by generating a spiral flow and turbulence; The inlet of the first-order cross-linking mixing tube is connected to the outlet of the polymer forced stretching system; The outlet of the second-stage cross-linking mixing tube is connected to the inlet of the polymer strong dispersion system.

2. The chemical flooding online continuous preparation and adjustment device according to claim 1, characterized in that: The SD-type spiral plates and the SK-type spiral plates are evenly staggered.

3. The on-line continuous preparation and adjustment device for chemical flooding according to claim 1 or 2, characterized in that: The polymer forced stretching system includes a multi-stage gear disc.

4. The chemical flooding online continuous preparation and adjustment device according to claim 1 or 2, characterized in that: The polymer intensive dispersion system includes a rotating packed bed.

5. Use of the chemical flooding online continuous preparation and control device according to any one of claims 1 to 4 in preparing chemical flooding profile control fluid.

6. A method for preparing a chemical flooding profile control fluid online, comprising the following steps: S1. Inputting the polymer dry powder into the polymer forced stretching system in the online continuous preparation and adjustment device for chemical flooding according to any one of claims 1 to 4 for stretching pretreatment to obtain a polymer solution; S2, the polymer solution is pre-dispersed through the SD-type spiral plate in the first-order cross-linking mixing tube in the cross-linking mixing system; the liquid cross-linking agent is injected through the cross-linking agent injection port on the venturi tube; S3, the polymer solution and the liquid crosslinking agent enter the second-stage crosslinking mixing tube for secondary mixing and dispersion; S4. The mixed and dispersed solution enters the polymer strong dispersion system for cross-linking and mixing again, thereby completing the online preparation of the profile control agent.

7. The method according to claim 6, characterized in that: The polymer intensive dispersion system uses a rotating packed bed to shear the solution.

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