Weak-base three-component combination flooding high-pressure binary scale reduction mixing system and method

Abstract

The invention relates to a weak-base three-component combination flooding high-pressure binary scale reduction mixing system and method.The scale reduction mixing system comprises a high-pressure sewage pipeline between a water injection station and an injection station, and a binary static mixer is arranged on the high-pressure sewage pipeline; a surface active agent and alkali liquor which are respectively conveyed by the surface active agent pipeline and the alkali liquor pipeline are mixed into high-pressure binary liquid through the binary static mixer, and then the high-pressure binary liquid is input into the injection station; the interface of the surfactant pipeline and the high-pressure sewage pipeline is positioned at the far end of the inlet of the binary static mixer, and the interface of the alkali liquor pipeline and the high-pressure sewage pipeline is positioned at the near end of the inlet of the binary static mixer; the problem that a high-pressure unitary pipe section, a high-pressure binary pipe section and a static mixer of an existing weak-base three-component combination flooding high-pressure binary distribution station are seriously scaled is effectively solved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of oilfield tertiary oil recovery technology, in particular to weak base ASP flooding surface pipeline fouling process optimization. BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and do not constitute prior art.

[0003] With the industrialization of weak base ASP flooding, the weak base ASP flooding target liquid adopts the "high pressure binary, low pressure binary" injection process. The high pressure binary liquid is alkali, surfactant and high pressure sewage. After mixing in proportion at the binary preparation station, it is transported to the injection station. The low pressure binary liquid is polymer, surfactant and low pressure sewage. After mixing at the preparation station, it is mixed with the high pressure binary liquid in a certain proportion at the injection station by the injection pump to form the weak base ASP target liquid, which is transported to the injection well through the static mixer and injected into the oil layer.

[0004] The "high pressure binary" injection process is completed by the original weak base ASP flooding high pressure binary mixing system of Figure 1 , which specifically disperses a certain amount of sodium carbonate dry powder uniformly in the preparation water, dissolves it preliminarily to prepare an 8% alkali solution, filters the outlet of the alkali dissolving tank by a centrifugal pump, and then transports it to the alkali storage tank for buffering at low pressure. Add high pressure sewage in proportion, and complete the preliminary mixing through the alkali static mixer to become high pressure binary liquid. 38% petroleum sulfonate surfactant is unloaded into the high-level heat preservation storage tank by tank truck, and dilution water is added at the same time. Dilute it into a 20% surfactant solution for storage, and add it to the high pressure binary liquid in proportion, and continue to mix with the high pressure binary liquid through the surfactant static mixer to become high pressure binary liquid and transport it to the injection station.

[0005] As shown in Figure 2 , a high pressure sewage pipeline is arranged between the injection station and the injection station. During the high pressure binary preparation process of the weak base ASP flooding, the high pressure binary liquid output by the alkali static mixer enters the high pressure binary pipe section of the high pressure sewage pipeline. The thick scale in the high pressure binary pipe section reaches 10 cm, and before entering the surfactant static mixer, it is mixed with the 20% surfactant solution and enters the surfactant static mixer together. The high pressure binary liquid output by the surfactant static mixer is transported to the injection station through the high pressure binary pipe section of the high pressure sewage pipeline. The thick scale in the high pressure binary pipe section reaches 5 cm.

[0006] Therefore, during the weak base ASP injection stage, the high pressure binary pipe section, the high pressure binary pipe section and the static mixer of the binary preparation station are seriously scaled. When the scaling is serious to a certain extent, it needs to be treated by acid washing or replacing the equipment pipeline, which has high technical difficulty and high production and maintenance cost.

[0007] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art. Summary of the Invention

[0008] In view of this, this disclosure provides a weak-alkali ternary composite drive high-pressure binary descaling mixing system and method to solve the problem of severe scaling in the high-pressure single-component pipe section, high-pressure binary pipe section and static mixer of the current weak-alkali ternary composite drive high-pressure binary mixing station.

[0009] Firstly, to achieve the aforementioned objectives, the weak-base ternary composite high-pressure binary scale-reducing mixing system disclosed herein comprises: The high-pressure sewage pipeline between the water injection station and the injection station is equipped with a binary static mixer. The surfactant and alkali solutions transported by the surfactant pipeline and the alkali solution pipeline are mixed by the binary static mixer and then input into the injection station. The interface between the surfactant pipeline and the high-pressure sewage pipeline is located at the far end of the inlet of the binary static mixer, while the interface between the alkali pipeline and the high-pressure sewage pipeline is located at the near end of the inlet of the binary static mixer.

[0010] In this disclosure and possible embodiments, a static surfactant mixer is disposed between the interface of the surfactant line and the high-pressure wastewater line and the interface of the alkali line and the high-pressure wastewater line.

[0011] Secondly, the weak-base ternary composite high-pressure binary scale-reducing mixing method described in this disclosure includes: The high-pressure binary solution is prepared using the scale-reducing mixing system described in the first aspect.

[0012] In this disclosure and possible embodiments, the surfactant is mixed with high-pressure wastewater to form a high-pressure unary liquid. When the high-pressure unary liquid flows to a near-binary static mixer, the alkaline solution is mixed with the high-pressure unary liquid and flows into the binary static mixer together. The binary static mixer mixes the alkaline solution and the high-pressure unary solution into a high-pressure binary solution, which is then fed into the injection station.

[0013] In this disclosure and possible embodiments, a surfactant static mixer is provided between the surfactant inlet and the alkali inlet.

[0014] In this disclosure and possible embodiments, the surfactant is diluted to a mass concentration of 20% using low-pressure wastewater, and then mixed with high-pressure wastewater to form the high-pressure unary liquid.

[0015] In this disclosure and possible embodiments, the alkali powder is prepared to a mass concentration of 8% using low-pressure wastewater, and then mixed with the high-pressure monolithic liquid.

[0016] In this disclosure and possible embodiments, the surfactant is a petroleum sulfonate with a mass concentration of 38%; the alkali powder is sodium carbonate powder.

[0017] The beneficial effects of this invention are as follows: This invention discloses a low-pressure ternary composite flooding high-pressure binary scale-reducing mixing system and method. Based on the field process and combined with scale formation analysis, it mixes the high-pressure binary fluid by first adding surfactants to the high-pressure wastewater and then adding alkali solution. Because the mixing sequence is different from the original method of adding alkali solution first and then surfactants, the severe scaling problem of the original method is easily solved, thereby effectively reducing the degree and rate of scaling. Moreover, since only the order of addition is changed and the amount of addition does not change, the "high-pressure binary, low-pressure binary" injection process is not changed, and the oil displacement effect of the low-pressure ternary composite flooding is not affected. This invention's scale-reducing mixing system and method, through innovative process optimization design, significantly reduces the scaling rate and solves the problem of severe scaling in the low-pressure ternary composite flooding high-pressure binary mixing system from the source. While meeting the oilfield development requirements for the ternary target fluid compatibility rate and system quality qualification rate, it reduces the scaling rate and degree of the high-pressure binary mixing system. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the specification, serve to illustrate the technical solutions of this disclosure.

[0019] Figure 1 This is a schematic diagram of the original weak-base ternary composite drive high-pressure binary mixing system; Figure 2 This is the original high-pressure binary alkali mixing process flow chart; Figure 3 This is a schematic diagram of a weak alkali ternary composite flooding high-pressure binary scale-reducing mixing system according to an embodiment of this disclosure; Figure 4 This is a flowchart of the alkaline mixture preparation process for Model 1. Figure 5 This is a flow chart for the mixing of two alkalis; In the diagram: 1-Aeration station, 2-Low-pressure aeration wastewater buffer tank, 3-Water supply pump, 4-Dispersion device, 5-Alkali dry powder tank, 6-Alkali storage tank, 7-Feeding pump, 8-High-pressure pump, 9-Water injection station, 10-Surfactant dilution pump, 11-Surfactant storage tank, 12-High-pressure plunger pump, 13-Injection station, 14-Petroleum sulfonate tanker, 15-Surfactant unloading pump. Detailed Implementation

[0020] The present disclosure is described below based on embodiments; however, it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, certain specific details are described in detail. However, those skilled in the art will fully understand the present disclosure for the parts not described in detail.

[0021] Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0022] To analyze the causes of scale formation, a statistical analysis of scale formation in a weakly alkaline injection system was conducted, and the results are shown in Table 1. Table 1. Statistical Table of Scaling in the Weak Alkali Block Injection System

[0023] As shown in Table 1 above, the weakly alkaline ternary system exhibits severe scaling due to the presence of carbonate ions in the alkaline solution, with carbonate scale dominating at different nodes. When only alkaline solution is present in the high-pressure unary section, the scaling rate reaches 24-30 mm / month. After adding surfactant, the scaling rate in the high-pressure binary section significantly decreases to 7-10 mm / month, and the scale softens, with a slight reduction in the proportion of carbonate scale. Therefore, the addition of surfactant to the alkaline solution results in a decrease in scaling rate and a softening of the scale.

[0024] Based on the above analysis of scale formation, it can be seen that if the order of adding surfactant and alkali to high-pressure wastewater is improved, the degree and rate of scaling can be effectively reduced without changing the "high-pressure binary, low-pressure binary" process and the concentration of the agents. That is, surfactant is added to high-pressure wastewater first, and then alkali is added. Since only the order of addition is changed, and the amount of addition does not change, the "high-pressure binary, low-pressure binary" mixing process is not changed, and the oil displacement effect of the weak alkali ternary composite flooding is not affected.

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the mixing system and mixing method of the present invention will be described in more detail below with reference to the accompanying drawings and examples.

[0026] Figure 3 This is a schematic diagram of a weak-base ternary composite high-pressure binary scale-reducing mixing system according to an embodiment of this disclosure, as shown below. Figure 3As shown, the weak alkali ternary composite high-pressure binary scale-reducing mixing system includes a high-pressure sewage pipeline between the water injection station and the injection station. A surfactant pipeline and an alkali solution pipeline are respectively connected to the high-pressure sewage pipeline. A binary static mixer is installed on the high-pressure sewage pipeline. The surfactant and alkali solution transported by the surfactant and alkali solution pipelines are mixed through the binary static mixer and then input into the injection station. The interface between the surfactant pipeline and the high-pressure sewage pipeline is located at the far end of the inlet of the binary static mixer, while the interface between the alkali solution pipeline and the high-pressure sewage pipeline is located at the near end of the inlet of the binary static mixer.

[0027] pass Figure 3 As shown in the system structure design, the surfactant mixes with the high-pressure wastewater before the alkali solution. The surfactant and high-pressure wastewater mix to form a high-pressure unary liquid. The high-pressure unary liquid flows through a section of the high-pressure unary pipe that does not contain alkali solution, and therefore, no scaling occurs in this section due to the presence of only surfactant. When the high-pressure unary liquid is delivered to the interface between the alkali solution pipeline and the high-pressure wastewater pipeline, the alkali solution and the high-pressure unary liquid mix and then enter a binary static mixer. Further mixing in the binary static mixer forms a high-pressure binary liquid.

[0028] During the above mixing process, the alkaline solution mixes with the surfactant in the high-pressure unary liquid when it enters the high-pressure sewage pipeline. Therefore, under the action of the surfactant, the scaling rate of the alkaline solution in the high-pressure sewage pipeline and in the binary static mixer will be significantly reduced. Even if scaling occurs, the scale will be soft and easy to remove. Therefore, without changing the "high-pressure binary, low-pressure binary" mixing process and the concentration of the reagents, the mixing system and mixing method disclosed herein can effectively reduce the severity of scaling in the system.

[0029] exist Figure 3 Preferably, a surfactant static mixer is also installed between the interface of the surfactant pipeline and the high-pressure sewage pipeline and the interface of the alkali pipeline and the high-pressure sewage pipeline; the surfactant and high-pressure sewage are uniformly mixed by the surfactant static mixer to form a uniform high-pressure monolithic liquid.

[0030] Because the conditions at the oilfield site differ, there are two scenarios: existing stations and newly built stations. Figure 1 The diagram shows the existing mixing system for existing stations. For the weak-base ternary composite flooding high-pressure binary scale-reducing mixing system and method disclosed in this paper, for the two scenarios mentioned above, while maintaining the same scale-reducing mixing principle, the details are different, corresponding to two modes, as follows: Mode 1: Adjust only the order of adding alkali and surfactant.

[0031] For existing oilfield stations, two static mixers are typically installed on the high-pressure wastewater pipeline between the water injection station and the injection station. Therefore, it is not necessary to add additional static mixers. The existing system can be modified simply by changing the interface positions of the surfactant and alkali solutions on the high-pressure wastewater pipeline. Figure 3 The diagram shows the mixing system structure of this patent. Because this first mode only requires modifications to some processes without affecting production, the infrastructure investment and management costs for the modifications are relatively low.

[0032] Combination Figure 4 The process shown in Model 1, which involves mixing surfactants, involves adding surfactants into the high-pressure sewage pipeline and mixing them into a high-pressure unary liquid via a static surfactant mixer. This mixture then enters a high-pressure unary pipe section of approximately 100 meters. At the end of this section (the interface between the surfactant solution and the high-pressure sewage pipeline), more surfactants are added. The surfactant solution and the high-pressure unary liquid are then mixed together via a static unary mixer to form a high-pressure binary liquid, which is then transported to the injection station.

[0033] Mode 2: Adjust the order of adding alkali and surfactant and mix them simultaneously.

[0034] refer to Figure 3 The mixed-use system structure, for newly built stations, can be designed as follows: Figure 5 The alkali-surfactant mixing process shown in the diagram allows for sufficient space to be reserved for process pipeline connections during plant construction, saving on infrastructure costs for high-pressure single-stage pipeline sections and static mixers; of course, whether or not to install a surfactant static mixer can be determined at the discretion of the client.

[0035] like Figure 5 As shown, during the mixing process, a surfactant is first added to the high-pressure sewage pipeline. The surfactant undergoes preliminary mixing with the high-pressure sewage in the high-pressure single-component pipeline section. The mixture is then transported to the end of the high-pressure single-component pipeline section (the interface between the alkaline solution and the high-pressure sewage pipeline) where alkaline solution is added. The alkaline solution and the high-pressure single-component liquid are then mixed into a high-pressure binary liquid through a binary static mixer and transported to the injection station.

[0036] Based on the weak-base ternary composite flooding high-pressure binary scale-reducing mixing system disclosed herein, taking Mode 1 as an example, the high-pressure binary scale-reducing mixing process is explained in detail as follows: A certain mass of alkali powder is added to the dispersion tank, and low-pressure sewage from the low-pressure aeration sewage buffer tank is pumped into the dispersion tank by a water supply pump. The alkali powder is evenly dispersed in the low-pressure sewage in the dispersion tank. The dissolved alkali powder is then prepared into an 8% mass concentration alkali solution, which is then transferred to the alkali storage tank for buffering by a centrifugal pump under low pressure.

[0037] The 38% petroleum sulfonate surfactant is unloaded by tanker truck into an elevated surfactant storage tank, preferably an insulated tank. Low-pressure wastewater from a low-pressure aeration wastewater buffer tank is pumped into the surfactant storage tank using a surfactant dilution pump to dilute the 38% petroleum sulfonate surfactant into a 20% petroleum sulfonate surfactant solution for storage.

[0038] When high-pressure binary mixing is required, the high-pressure plunger pump is turned on, and a 20% petroleum sulfonate surfactant solution is introduced into the high-pressure sewage pipeline according to the design ratio. When the high-pressure unary liquid, which is a mixture of surfactant and high-pressure sewage, flows through the interface between the alkaline solution and the high-pressure sewage pipeline, an 8% mass concentration alkaline solution pumped by the feed pump and the high-pressure pump is introduced according to the design ratio. Here, the alkaline solution and the high-pressure unary liquid are mixed and enter the binary static mixer for further mixing into a uniform high-pressure binary liquid. The mixed high-pressure binary liquid continues to be introduced into the injection station along the high-pressure binary pipeline section, completing the high-pressure binary mixing.

[0039] The scale reduction mixing method disclosed herein was applied to the east and west blocks of the North 1-2 Drainage Station and the North 1-District Interchange. This block is an existing substation. Using Mode 1 of the method, and comparing it with the original mixing process, the original mixing system pipeline was adjusted. The adjusted mixing system structure is as follows: Figure 3 As shown, by utilizing the adjusted mixing system structure, a high-pressure binary mixing process is carried out by first adding the surfactant and then the alkali.

[0040] After on-site operation, the scaling rate of the high-pressure binary mixture system, the concentrations of alkali and surfactant at the injection wellhead, and the interfacial tension of the ternary composite system were monitored. When the surfactant was added to the high-pressure wastewater, the scaling rate of the high-pressure uni-component pipe section was 0 mm / d, and the pipeline no longer scaled. After adding alkali, the scaling rate of the high-pressure binary pipe section was 0.4 mm / d, lower than the 0.5 mm / d scaling rate of the original method shown in Table 2, and the scale was soft. Simultaneously, while reducing the degree and rate of scaling, the qualified rate of alkali and surfactant concentrations reached over 98%; the interfacial tension of the ternary composite system reached 100%.

[0041] The method disclosed herein will be applied to the North 1st and 2nd Row East Block. This block is a newly built station and adopts... Figure 5 The process shown in Mode 2 involves high-pressure binary injection, where surfactant is first added in a set ratio, and the surfactant is mixed with high-pressure wastewater to form a high-pressure unary liquid. When the high-pressure unary liquid flows to the alkali interface, a set ratio of alkali is added and mixed with the high-pressure unary liquid. After being uniformly mixed in the binary static mixer, it is input into the injection station for high-pressure binary injection, achieving simultaneous addition and mixing.

[0042] After on-site operation, the scaling rate of the high-pressure binary mixing system, the concentrations of alkali and surfactant at the injection wellhead, and the interfacial tension of the ternary composite system were monitored. As shown in Table 2, when the surfactant and alkali were simultaneously added to the high-pressure water, the scaling rate of the high-pressure binary pipe section was 0.3 mm / d, lower than the 0.5 mm / d of the original method, and the scale was soft; while the high-pressure uni-component pipe section corresponding to the original method showed no scaling. Simultaneously, while reducing the degree and rate of scaling, the qualified rate of alkali and surfactant concentrations reached over 98%; the interfacial tension of the ternary composite system reached 100%.

[0043] Table 2 Comparison of scaling rates between the two methods and the original method

[0044] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technical improvements to the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A weakly alkaline ternary composite high-pressure binary scale-reducing mixing system, characterized in that, include: The high-pressure sewage pipeline between the water injection station and the injection station is equipped with a binary static mixer. The surfactant and alkali solutions transported by the surfactant pipeline and the alkali solution pipeline are mixed into a high-pressure binary solution by the binary static mixer and then input into the injection station. The interface between the surfactant pipeline and the high-pressure sewage pipeline is located at the far end of the inlet of the binary static mixer, while the interface between the alkali pipeline and the high-pressure sewage pipeline is located at the near end of the inlet of the binary static mixer.

2. The weak-base ternary composite high-pressure binary scale-reducing mixing system according to claim 1, characterized in that: A static surfactant mixer is installed between the interface of the surfactant pipeline and the high-pressure sewage pipeline and the interface of the alkali pipeline and the high-pressure sewage pipeline.

3. A method for mixing a weakly alkaline ternary composite high-pressure binary scale reducer, characterized in that, include: The high-pressure binary solution is prepared using the scale-reducing mixing system described in claim 1 or 2.

4. The method for mixing a weak alkali ternary composite high-pressure binary scale reducer according to claim 3, characterized in that: The surfactant is mixed with high-pressure wastewater to form a high-pressure unary liquid. When the high-pressure unary liquid flows to the near-binary static mixer, the alkaline solution is mixed with the high-pressure unary liquid and flows into the binary static mixer together. The binary static mixer mixes the alkaline solution and the high-pressure unary solution into a high-pressure binary solution, which is then fed into the injection station.

5. The method for mixing a weak alkali ternary composite flooding high-pressure binary scale reducer according to claim 4, characterized in that: A static mixer for surfactants is installed between the surfactant inlet and the alkali inlet.

6. The method for mixing a weak alkali ternary composite high-pressure binary scale reducer according to any one of claims 3-5, characterized in that: The surfactant is diluted to a mass concentration of 20% using low-pressure wastewater and then mixed with high-pressure wastewater to form the high-pressure unary liquid.

7. The method for mixing a weak alkali ternary composite flooding high-pressure binary scale reducer according to claim 6, characterized in that: The alkaline dry powder is prepared to a mass concentration of 8% using low-pressure wastewater, and then mixed with the high-pressure monolithic liquid.

8. The method for mixing a weak alkali ternary composite high-pressure binary scale reducer according to claim 7, characterized in that: The surfactant is a petroleum sulfonate with a mass concentration of 38%; the alkali powder is sodium carbonate powder.

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