Foam scrubbing agent with low foam water content for drainage gas recovery

Abstract

The invention discloses a foam scrubbing agent with low foam water content for drainage gas recovery. The foam scrubbing agent is prepared from the following components in percentage by volume: 95% of compound betaine, 3% of a nano foam stabilizer and 2% of a fluorocarbon surfactant, the compound betaine is formed by compounding sodium alpha-olefin sulfonate and cocamidopropyl betaine, and the compounding ratio of the sodium alpha-olefin sulfonate to the cocamidopropyl betaine is 1: 2; the nano foam stabilizer is a fumed silica aqueous solution, and the mass fraction of silica is 2%; the fluorocarbon surfactant is a nonionic fluorocarbon surfactant; the low-foam-water-content foam scrubbing agent for water drainage gas recovery can solve the problems that an existing foam scrubbing agent is large in wellbore pressure drop and difficult in liquid carrying in a low-pressure low-yield gas well, and has good foaming height and foam stabilizing performance under the condition that the foam water content is greatly reduced; the foam scrubbing agent with low foam water content for drainage gas recovery provided by the invention has the advantages of few types and dosage of used agents, simple preparation, and no damage to a reservoir after injection.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field chemical agents, specifically to a low-foaming-moisture-content foaming agent for drainage and gas production. Background Technology

[0002] Foam drainage gas production technology plays a crucial role in the development of water-bearing gas wells. It significantly improves the gas's liquid-carrying capacity, reduces wellbore liquid accumulation, and extends the well's later production time, thereby increasing the final recovery rate. However, as well pressure and production decrease, the well's output gradually approaches or falls below the critical flow rate for conventional foam drainage, leading to increasingly poor drainage efficiency and profitability. After foam drainage, well shut-in, repressurization, and further liquid release are necessary, resulting in a large workload and disruption to normal well production.

[0003] The conventional approach to foaming agents is to create foam that reduces gas-liquid surface tension and liquid density, while simultaneously requiring a high water content to remove as much water as possible in a single foaming operation. However, higher water content leads to greater foam density and consequently, higher gas-liquid mixture density, causing conventional foaming to fail once the well flow rate decreases to a certain level. To address the inefficiency or ineffectiveness of conventional foaming agents in low-pressure, low-production wells, a novel foaming agent with lower surface tension and lower water content than conventional foaming agents needs to be developed, based on the critical foam-carrying flow rate calculation theory.

[0004] Currently, there are few patent documents related to low-foaming water-content foaming agents. For example, Chinese patent publication number CN111218267A discloses a low-foaming water-content foaming agent and its preparation method. This foaming agent is composed of 35%-40% dioctylmethylhydroxysulfonylpropyl betaine, 0.1%-1% sodium perfluorooctyl sulfonate, 1%-4% polyethylene glycol 6000, and 55%-60% water. It can significantly and effectively improve the poor foaming operation effect under ultra-low pressure and low production conditions such as bottom hole flowing pressure below 10MPa and gas well flow rate less than 5000m3 / d. However, the foam height of this foaming agent is generally low, and the liquid carrying capacity of the foaming agent has not been tested. Summary of the Invention

[0005] The purpose of this invention is to provide a low-foaming-water-content foaming agent for drainage and gas production, in order to solve the problems of large wellbore pressure drop and difficulty in liquid carrying in existing foaming agents in low-pressure, low-production wells.

[0006] The present invention is achieved as follows: a low foam moisture content foaming agent for drainage and gas extraction, which is composed of the following components by volume percentage: 95% compound betaine, 3% nano foam stabilizer, and 2% fluorocarbon surfactant.

[0007] Furthermore, the compound betaine is composed of sodium α-alkenyl sulfonate and cocamidopropyl betaine, wherein the compounding ratio of sodium α-alkenyl sulfonate and cocamidopropyl betaine is 1:2.

[0008] Furthermore, the nano-foam stabilizer is an aqueous solution of fumed silica, wherein the mass fraction of silica is 2%.

[0009] Furthermore, the silica is fumed silica powder with a specific surface area of ​​200 m² / g.

[0010] Furthermore, the fluorocarbon surfactant is a nonionic fluorocarbon surfactant.

[0011] Compared with existing technologies, the beneficial effects of this invention are as follows: The low-foaming-water-content foaming agent for drainage and gas production provided by this invention can solve the problems of large wellbore pressure drop and difficulty in liquid carrying in low-pressure, low-production wells using existing foaming agents. It can achieve good foaming height and foam stabilization performance while significantly reducing foam water content. The low-foaming-water-content foaming agent for drainage and gas production provided by this invention uses fewer types and amounts of reagents, and the preparation steps are simple. It will not cause reservoir damage after injection. The nano-foam stabilizer can effectively reduce the liquid film drainage rate and significantly improve foam stabilization capability; the non-ionic fluorocarbon surfactant, with its high surface activity, reduces the surface tension of the foaming agent system, which is beneficial to foam formation. Therefore, through the synergistic effect of multiple surfactants, the generated foam is finer and more stable, with a lower foam water content. Detailed Implementation

[0012] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0013] The following detailed explanation, in conjunction with specific embodiments, further illustrates the following:

[0014] Example

[0015] A low-foaming, moisture-content foaming agent for drainage and gas extraction comprises the following components by volume percentage: 95% compound betaine, 3% nano-foam stabilizer, and 2% fluorocarbon surfactant. The compound betaine is composed of sodium α-alkenyl sulfonate and cocamidopropyl betaine in a 1:2 ratio. The nano-foam stabilizer is an aqueous solution of fumed silica, with a silica mass fraction of 2%. The silica is fumed silica powder with a specific surface area of ​​200 m² / g. The fluorocarbon surfactant is a nonionic fluorocarbon surfactant.

[0016] Preparation method: Slowly stir the compound betaine, nano foam stabilizer and fluorocarbon surfactant in a container until they are evenly mixed, and let stand to obtain the low foam moisture content foaming agent for drainage and gas extraction.

[0017] The low-foaming-water-content foaming agent for gas production provided by this invention comprehensively considers the synergistic effect between surfactants. It introduces nano-hard particles into a foam system composed of gas and water phases, allowing the nanoparticles to adsorb at the gas / water interface and form a solidified film that prevents bubble aggregation and disproportionation. This transforms the liquid film from a "fluid state" to a "fixed state," thereby reducing the liquid film drainage rate and improving foam stabilization. A small amount of non-ionic fluorocarbon surfactant is added to reduce the surface tension of the foaming agent system due to its high surface activity. The foam produced by this agent is fine and stable, with a lower water content than existing foaming agents. During the lift process, it can control the liquid carrying capacity and reduce the density of the gas-liquid mixture in the wellbore, achieving the foaming operation requirements of "small-volume drainage per cycle, multiple drainages of accumulated liquid in the wellbore" for low-pressure, low-production gas wells.

[0018] Verification Example

[0019] 1) Foaming and foam-stabilizing performance test

[0020] A simulated formation water with a mineralization of 80,000 mg / L was prepared according to the mass ratio of NaCl:CaCl2:MgCl2 = 7:0.6:0.4. Aqueous solutions were prepared at a usage concentration of 0.3%, and the Ross-Miles method was used to test the water, recording the initial bubble height, the bubble height at 5 minutes, and the bubble height at 10 minutes. The results are shown in Table 1.

[0021] Table 1 Comparison of Performance Indicators Test Results of Foaming Agents

[0022]

[0023] 2) Foam moisture content performance test experiment

[0024] A simulated formation water with a mineralization of 80,000 mg / L was prepared according to the mass ratio of NaCl:CaCl2:MgCl2 = 7:0.6:0.4; aqueous solutions were prepared according to a usage concentration of 0.3%. The specific determination method was as follows: the lower cock of the Roche foam apparatus was closed, the solution was poured into the Roche foam apparatus, the collection tube was connected, and the collection tube was connected to a 1000 mL measuring cup. An air flow of 8 L / min was introduced to generate foam. When the foam reached the 1000 mL mark, foam collection was stopped, the measuring cup was sealed, and the liquid volume was measured after the foam naturally collapsed. The proportion of liquid volume to the measuring cup volume is the foam water content. The results are shown in Table 2.

[0025] Table 2 Comparison of Foam Moisture Content Test Results for Foaming Agents

[0026] Types of detoxifying agents Foam moisture content, % This invention relates to a low-foaming moisture-content foaming agent (0.3% concentration). 1.16 This invention relates to a low-foaming moisture-content foaming agent (0.3% concentration). 1.15 A certain low-pressure, low-yield foaming agent 1 (concentration 0.3%) 1.7 A certain low-pressure, low-yield foaming agent 2 (concentration 0.3%) 1.8 A certain low-pressure, low-yield foaming agent 3 (concentration 0.3%) 1.8

[0027] In summary, the low foam moisture content foaming agent for drainage and gas extraction provided by this invention has the characteristics of high initial foaming, strong foam stabilization ability, good liquid carrying capacity, and low foam moisture content, which is superior to the prior art.

[0028] In summary, the low-foaming-moisture-content foaming agent for drainage and gas extraction provided by this invention has the following application prospects:

[0029] The low-foaming-water-content foaming agent for drainage and gas production provided by this invention can solve the problems of large wellbore pressure drop and difficulty in liquid carrying in low-pressure, low-production gas wells by existing foaming agents. With a significant reduction in foam water content, it has good foaming height and foam stabilization performance, which can reduce the gravity gradient of the gas-liquid column in the wellbore, ensure stable production of gas wells under low-pressure, low-production conditions, further reduce the lower limit of foaming process application, and effectively solve the foaming problem of low-pressure, low-production gas wells with a wellhead pressure of 1.0 MPa and a gas production of 2000 m3 / d.

[0030] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-foaming-moisture-content foaming agent for drainage and gas extraction, characterized in that: It consists of the following components by volume percentage: 95% compound betaine, 3% nano foam stabilizer, and 2% fluorocarbon surfactant.

2. The low-foaming-moisture-content foaming agent for drainage and gas extraction according to claim 1, characterized in that, The compound betaine is composed of sodium α-alkenyl sulfonate and cocamidopropyl betaine, and the ratio of sodium α-alkenyl sulfonate to cocamidopropyl betaine is 1:

2.

3. The low-foaming-moisture-content foaming agent for drainage and gas extraction according to claim 1, characterized in that, The nano-foam stabilizer is an aqueous solution of fumed silica, wherein the mass fraction of silica is 2%.

4. The low-foaming-moisture-content foaming agent for drainage and gas extraction according to claim 3, characterized in that, The silica is fumed silica powder with a specific surface area of ​​200 m² / g.

5. The low-foaming-moisture-content foaming agent for drainage and gas extraction according to claim 1, characterized in that, The fluorocarbon surfactant is a nonionic fluorocarbon surfactant.

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