About sulfur in petroleum

Sulfur removal agent is a chemical substance that can remove hydrogen sulfide from crude oil and associated gas in oil and gas fields, and they can achieve the purpose of desulfurization through different methods and processes, so as to protect the safety of equipment, environment and personnel.

Why are there sulfurous substances in the oil extraction process?

First, the oil itself contains hydrogen sulfide, or sulfur-containing organic matter, which is released when the oil is extracted.

Secondly, sulfur-containing substances in the formation, under the conditions of high temperature and pressure, undergo thermochemical reduction reaction with water or organic hydrocarbons to produce hydrogen sulfide. Through channels such as cracks, hydrogen sulfide from the sulphate layer in the lower formation flows upward.

Sulfur-containing substances in petroleum can be divided into:

• Active sulfides: elemental sulfur, hydrogen sulfide and mercaptan. These substances are strongly corrosive to equipment, and SO2 is generated when burned, causing environmental pollution.

• Inactive sulfides: thioether, disulfide and thiophene. These substances have no corrosive effect on metal equipment, but will be converted into active sulfides when decomposed by heat.

The sulfur content and distribution in petroleum are related to the quality of crude oil, geological age, burial depth and other factors. In general, oil with a sulfur content higher than 2.0% is called high sulfur oil, less than 0.5% is called low sulfur oil, and between 0.5% and 2.0% is called sour oil. The data show that the sulfur content of gasoline distillate is the lowest and that of vacuum residue is the highest.

Sulfur removal agents are commonly used in the process of oilfield exploitation, generally the most common is triazine compounds, which is a six-membered heterocyclic compound containing three nitrogen atoms, which can produce irreversible chemical reactions with sulfur-containing substances in crude oil (such as hydrogen sulfide, thioether, etc.) to generate water-soluble thiadiazine compounds, so as to achieve the purpose of desulfurization.

The triazine sulfur removal agent can be directly injected into the raw material gas pipeline, the hydrogen sulfide is removed through chemical reaction, and the chemical substances contained in the desulfurization waste liquid can be used as fertilizer and sewage treatment agents, etc., and the process does not have the problem of secondary pollution.

Triazines have several advantages for the removal of sulfur-containing substances in crude oil:

• Fast reaction speed, high sulfur removal efficiency, good selectivity, can effectively remove low concentration of hydrogen sulfide.

• Sulfur removal products are water-soluble liquids, high safety, do not need to be recycled, can be directly injected back into the formation or used as fertilizer, sewage treatment agents, etc.

• The sulfur removal agent itself is low toxic, biodegradable, and has little impact on environmental pollution and site operation safety.

• The effective content of sulfur eliminator is high, which can achieve rapid and effective desulfurization under small dosage.

• The cost of the desulfurizer is relatively low and is not affected by the quality and temperature of the crude oil