Water-based microcapsule sand washing composition for highly acidic gas wells, water-based microcapsule sand washing fluid for high acid gas wells

Abstract

The invention relates to a water-based microcapsule sand washing composition for high-acid gas wells and a water-based microcapsule sand-washing fluid for high-acid gas wells, belonging to the technical field of oil field chemistry. The water-based microcapsule sand washing composition for acid gas wells of the present invention is composed of the following components in parts by weight: 0.6-1.3 parts of foaming agent, 1.5-2.8 parts of capsule membrane enhancer, 1.2-2.2 parts of foam stabilizer, except 2.5-4.7 parts of sulfur agent, 2.5-3.5 parts of corrosion inhibitor; the foam stabilizer includes alcohol amine anti-sulfur foam stabilizer with the structure shown in the following formula: wherein R 1 , R 3 Independently selected from hydrocarbon groups with carbon number ≤ 3, R 2 for-CH 3 or -H. The water-based microcapsule sand washing composition for high-acid gas wells of the present invention has technical advantages such as stable sand-carrying performance and less back pressure on low-pressure reservoirs under high-acid gas environments, and can significantly reduce the loss of sand washing fluid for high-acid gas and low-pressure gas wells and reservoir damage, and improve the safety and reliability of sand flushing operations in high-acid gas wells.

Description

technical field [0001] The invention relates to a water-based microcapsule sand washing composition for high-acid gas wells and a water-based microcapsule sand-washing fluid for high-acid gas wells, belonging to the technical field of oil field chemistry. Background technique [0002] The sand washing process is to use fluid to break up the bottom sand blockage, and use the carrying capacity of the liquid flow to bring the broken sand out of the ground, remove the sand in the wellbore, and restore the reservoir productivity of the sand buried section of the oil and gas well. Foam fluid has the advantages of low hydrostatic column pressure, small filtration loss, good sand-carrying performance, strong drainage ability and little damage to formation, so it is widely used in sand flushing construction of gas wells. [0003] Highly sour gas reservoirs refer to the H in the produced natural gas 2 Higher S content (usually H 2 S content greater than 2%), and accompanied by more ...

AI Technical Summary

Problems solved by technology

In the sand washing construction of highly acidic gas wells, the use of nitrogen (or liquid nitrogen) foam fluid sand washing technology has the following two shortcomings: one is the need for nitrogen collection (storage) devices, high-pressure nitrogen pumping equipment and foam generators. Second, it is difficult to accurately control the injection volume and discharge volume of nitrogen foam fluid, which leads to unstable density of foam sand washing fluid in the wellbore. When the reservoir is under pressure, there is a risk of a major safety accident that high-pressure hydrogen sulfide escapes from the reservoir, so nitrogen (or liquid nitrogen) foam fluid sand washing technology is not suitable for sand washing operations in high-acid gas wells

[0005] During on-site construction of the low-density temporary plugging foam fluid sand washing technology, the construction equipment and process are relatively simple, and a reasonable density value of the temporary plugging sand washing fluid can ensure that the sand washing construction can be completed under a positive pressure difference environment, and there is a risk of hydrogen sulfide escape. However, the existing low-density foam sand washing fluid formula system will encounter the following two types of problems when encountering acid gas: one is that the acid gas reacts with the foam sand washing fluid, and incompatibility such as precipitation and delamination occurs, resulting in sand washing The sand-carrying performance of the liquid drops sharply, affecting the normal sand washing operation, and in severe cases, it will cause major safety accidents such as hydrogen sulfide escape from the ground; second, the acid gas affects the stability of the sand washing foam liquid, resulting in insufficient pressure bearing capacity of the foam liquid The fluid loss is too large, which aggravates the reservoir damage and increases the fluid consumption and construction cost

However, since the alcohol amine foam film agent is mainly composed of intermolecular amine groups and hydroxyl groups, and the longest carbon chain length of the alcohol substance is 15, the alcohol amine foam film agent has a large intermolecular steric position. The resistance effect affects the encapsulation and protection strength of the microbubbles, resulting in relatively weak high-temperature pressure bearing capacity of the microbubbles, and the large fluid loss of the sand washing foam, which aggravates the damage to the reservoir and increases the amount of liquid and construction costs.

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