Introduction to Basic Knowledge of Surfactants in Oil Fields
According to the classification method of oilfield chemicals, oilfield surfactants can be divided by the application into surfactants for drilling, surfactants for mining, surfactants for improving yield, surfactants for oil and gas gathering, and surfactants for water treatment, etc.
Surfactant for drilling
The amount of surfactants for drilling (including drilling fluid treatment agents and oil well cement admixtures) is the largest, accounting for about 60% of the total surfactants used in oilfields. The amount of surfactants for oil recovery relatively is small, but its technical content is higher. Its amount accounts about 1/3 of the total amount of surfactants used in oil fields. These two types of chemicals occupy an important position in surfactants in oil fields.
At present, the research on the world's drilling fluid treatment agent has formed the situation of "three pillars" in the United States, Russia and China. The United States is taking various new polymer materials as the research object. Russia is mainly based on the principle that "the raw materials are cheap and easy to obtain", and various industrial wastes. Chinese research focuses on the full use of traditional raw materials and the development of new synthetic polymers (including monomers).
The research focus of foreign drilling fluid treatment agents is more prominent, that is, various products based on synthetic polymers containing sulfonic acid groups, which is also the future development direction.
Since the 1990s, a new generation of polymer 2-acrylamide-2-methylpropanesulfonic acid (AMPS) multi-copolymer products has become the representative of new drilling fluid treatment agents. Breaker progress has been made in the varieties of viscosity reducers, fluid loss reducers and lubricants. Especially in recent years, polymeric alcohol surfactants with cloud point effect have been popularized and applied in all domestic oil fields and series of polymeric alcohol drilling fluid system.
In addition, methyl gluconate and glycerin-based drilling fluids have achieved good results in field applications, showing good application prospects and promoting the development of surfactants for drilling fluids. At present, China's drilling fluid treatment agent has grown to 18 categories, thousands of varieties, with an annual consumption of nearly 300,000 tons.
In the 1980s, oil well cement admixtures developed rapidly in the 1980s, and a series of products were gradually formed. In the development of new products, synthetic polymer materials are generally the preferred research set; in 1993, all oil well cements in China were converted into series that met API standards. The products and admixtures have developed rapidly. The company has successfully developed a special oil well cement dispersant SAF (sulfonated acetone formaldehyde polycondensate), which is closely related to cementing quality and pumping layer protection. Coagulants, retarders and adhesive reinforcing agents have also shown good development momentum, and formed a special oil well cement admixture. At present, it has developed into more than 200 varieties of 11 categories, with an annual dosage of several thousand tons.
Surfactant for oil recovery
There are relatively few varieties and quantities of surfactants for oil recovery compared with surfactants for drilling, especially for acidification and fracturing products. Among the surfactants for fracturing, gelling agents have been researched to modify natural vegetable gums and cellulose, as well as various synthetic polymers such as polyacrylamide.
In recent years, foreign countries have developed relatively slowly in the field of acidified surfactants. The focus of research and development is on the development of corrosion inhibitors for acidification. It is characterized by the use of existing raw materials to modify or compound corrosion inhibitors. The raw materials and products are non-toxic or low-toxic, and the products have oil/water solubility or water dispersibility.
Amines, quaternary ammonium and acetylenic alcohols have a large number of corrosion inhibitors, and aldehyde corrosion inhibitors have been relatively less developed due to their toxicity. Corrosion inhibitors are also complexes of dodecylbenzenesulfonic acid and low molecular amines (ethylamine, propylamine, C8-18 primary amine, oleic acid diethanolamide), and emulsifiers are oil-in-oil emulsifiers.
Mainly, in recent years, the research on surface active agents for fracturing acidified liquids in China has not been enough, and little progress has been made. In addition to corrosion inhibitors for fracturing acidification fluids during development, there are many other varieties, most of which are amines (primary amines, secondary amines, tertiary amines, quaternary amide or their compounds), imidazoline and its derivatives are also a class of organic corrosion inhibitors that are used in larger amounts.
Surfactants for oil and gas gathering
The research, development and utilization of surfactants for oil and gas gathering and transportation in China began in the 1960s, and there are currently 14 types and hundreds of products. Among them, the crude oil demulsifier is the largest, and the annual demand is about 20,000 tons. China has developed suitable demulsifier products for different oil fields, many varieties have reached the international level in the 1990s; while pour point depressants, flow improvers, viscosity reducers and anti-wax agents are few, and most of them are For complex products, different crude oils have different requirements and difficulties for the development of new products due to different requirements for surfactants used for depressing, flow improvement, viscosity reduction and wax removal purposes.
Surfactant for oil field water treatment
. Oilfield water treatment agent is an important type of oilfield chemical in the development of oil. The annual dosage of various water treatment agents is above 60,000 tons, of which surfactant accounts for about 40%, although surfactants in oilfield water treatment The demand is very large, but there are few researches on surfactants for water treatment in China. The varieties of surfactants for oilfield water treatment are not complete, and most of the products are imported from the industrial water treatment industry, but due to oilfield water. The complexity of the products introduced directly from industrial water treatment is poorly applicable, sometimes not effective, and there is no targeted oilfield water treatment surfactant. Foreign research on surfactants for water treatment is most active in the development of flocculants, and there are many products developed, but not many sewage treatments for oil and gas fields.
Surfactant for tertiary oil recovery
The quality of surfactant products for tertiary oil recovery in foreign countries is stable and the scale of production is large. At present, some kinds of surfactants and polymers for oil displacement have been formed in China, but they cannot meet the needs of tertiary oil recovery. The annual production of heavy alkylbenzenes for surfactants used in synthetic oil displacing agents is less than 20,000 tons, which is difficult to meet the needs, and the molecular weight and molecular weight distribution are not suitable for the surfactants used in synthetic oil displacing agents.
Although a lot of work has been done on the surfactant, it still cannot meet the needs of oilfield flooding, and there are problems in production scale and product quality. Daqing, Shengli, Liaohe, Dagang and other oil fields have already implemented polymer flooding, Daqing Oilfield has built a polyacrylamide plant with an annual output of 57,000 tons, and Shengli Oilfield has built a polyacrylamide plant with an annual output of more than 20,000 tons.
Some other production enterprises have a production capacity of more than 100,000 t/year. The current annual demand for polymer for oil displacement is tens of thousands of tons. The scale can basically meet the needs, but the product quality (such as relative molecular mass) There is still a gap between it and solubility, temperature resistance and salt saturation. Among the surface active agents in oil fields, tertiary oil recovery surfactants are the most promising chemicals.
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