Factors of paraffin formation in oil Wells and methods of paraffin removal

The fundamental reason why oil Wells wax during production is that the crude oil produced by oil Wells contains wax.

1.Factors of paraffin formation in oil Wells

(1) Composition and temperature of crude oil

Under the same temperature condition, the solubility of light oil to wax is greater than that of heavy oil, the more light components contained in crude oil, the lower the crystallization temperature of wax, that is, the wax is not easy to precipitate, and the more wax to maintain the dissolved state.

(2) Pressure and dissolved gas

Under the condition that the pressure is higher than the saturation pressure, the crude oil will not degas when the pressure is reduced, and the initial crystallization temperature of the wax will decrease with the decrease of the pressure. In addition, the dissolved gas also expands and absorbs heat when separating from the oil, which reduces the oil flow temperature and is conducive to the precipitation of wax crystals.

(3) Colloid and asphaltene in crude oil

The experimental results show that the crystallization temperature can be reduced with the increase of gum content in petroleum. However, when the wax deposited in the tube wall contains gum and asphaltene, it will form hard wax, which is not easy to be washed away by the oil flow.

(4) Mechanical impurities and water in crude oil

The mechanical impurities in the oil will become the crystalline core of the paraffin precipitation, making the wax crystals easy to gather and grow, and speeding up the process of closing the wax. In addition, wax formation will be serious when the water content is low, because the salts in the water precipitate and deposit on the pipe wall, which is conducive to the accumulation of wax crystals.

(5) Flow velocity, roughness of pipe surface

High production well fluid flow rate, low heat loss, high oil flow temperature, wax is not easy to precipitate. Even if wax is precipitated, it is not easy to deposit on the tube wall. If the wall of the tube is rough, the wax crystal is easy to adhere to the above to form wax formation, and the other side is not easy to wax formation.

2.Oil well paraffin removal method

(1) Wax scraping sheet to remove wax

(2) Casing wax scraping

(3) Electrothermal paraffin removal

(4) Thermochemical wax removal

(5) Hot oil cycle paraffin removal

(6) Steam paraffin removal