Low boiling point methane-based light hydrocarbons, carbon dioxide, and hydrogen sulfide can easily combine with water molecules to form cage-like ice-like solid hydrates under certain temperature and pressure conditions. In the process of oil and gas exploitation and transportation, because part of the water in the natural gas condenses on the inner wall of the pipeline, the flow diameter of the medium in the pipe will become smaller, the flow will be blocked, and the energy consumption will increase. In severe cases, it will cause partial ice blockage of the pipeline. How to prevent and eliminate the formation of hydrates to ensure the safe operation of gas pipelines has attracted great attention.
At present, the main methods to inhibit the formation of hydrates are: dehydration method, depressurization method, heating method, and chemical inhibitor addition method. Among them, chemical inhibitor is the most commonly used and effective method. Traditionally used alcohol or electrolyte thermodynamic inhibitors avoid and prevent the formation of hydrates by changing the temperature and pressure conditions of hydrate formation. This thermodynamic inhibitor has the disadvantages of large consumption, high content (generally 10% -60% of the mass fraction of the water phase), high cost, etc., and this type of inhibitor also has the dangers of flammability, explosion, toxicity, corrosion, and environmental pollution. , Which has an adverse impact on the safety production and operators of oil and gas stations. Since the 1990s, domestic and foreign has been committed to the development of low-dose inhibitors to replace thermodynamic inhibitors, which have the advantages of small addition amount, obvious effect, low use cost, and environmental friendliness. Kinetic inhibitors can slow or even stop the growth of hydrate grains, delay the time of hydrate nucleation and growth, and prevent the growth of hydrate grains. The kinetic inhibitor is adsorbed on the surface of the hydrate particles, and its ring structure is combined with the hydrate crystals through hydrogen bonds, thereby preventing and delaying the growth of the hydrate crystals.
The following describes several inhibitors and their preparation methods:
The Shell patent mentions a method for preparing dendritic polyamide ester, and uses it as a hydrate inhibitor to inhibit the formation of hydrates in natural gas pipelines. It does not involve polyester graft copolymers and their use as hydrate inhibitors. Applications.
The BASF patent mentions a graft copolymer of polyamide which reacts with maleic anhydride and contains at least one ethylenically unsaturated side chain, said grafted side chain containing at least one N-vinylpyrrolidone and / Or the representative of N-vinyl caprolactam, and the graft copolymer is used as a gas hydrate inhibitor in the transportation and transportation of oil and gas, and the graft copolymer only involves the branched product of polyamide.
Another patent mentions an inhibitor for preventing the formation of natural gas hydrates in high-sulfur gas fields. The inhibitor is composed of N-vinylpyrrolidone, China N-Vinyl Caprolactam CAS 2235-00-9 and N,N-dimethylamino methacrylate. It is composed of a mixture of ester terpolymers, polyamide esters, surfactants, and alcohols. In this patent, polyamide esters are only reported as an effective component.