Methods of removing deposits in oil and gas pipelines: a review.

Deposition in the oil, gas, and petrochemical industries occurs mainly due to the passage of water, organic deposits, and corrosion products in hydrocarbon pipelines. The composition of deposits in oil and gas pipelines differs at different points and routes. Especially, deposition in long-distance transmission lines is often due to mineral and organic deposits. Variable environmental conditions such as the mixed fluid types in pipelines, pressure, temperature, pH, hydrocarbon type, and pipe material can accelerate the deposition process. Consequently, these variations reduce effective pipe diameter and increase destructive corrosion factors and microbiological phenomena. Chemical methods with special inhibitors and suitable solvents are a common method for removing these deposits. Moreover, phosphonate and polycarboxylate inhibitors are consumed for removing mineral deposits, and aromatic solvents and surfactants for organic deposits. Mechanical methods, e.g., pigging, have become a fully cost-effective method in long-distance pipelines. Recently, new methods such as nano-coatings and superhydrophobic coatings on the pipe wall and electromagnetic or ultrasonic systems to create vibrations and destroy mineral deposits growing in the pipe have been considered low-cost solutions in some places. In this analytical review study, considering Iranian diverse climatic conditions, combined solutions with modern technologies were selected as the best approach for managing deposition and corrosion and were introduced as solutions to advance productivity.