Synthesis of Chemical Additives and Their Role as Pour Point Depressant Flow Improver on Indian Crude Oils

Abstract

Increase in global energy demand consumption shifts hydrocarbon resource exploitation towards harsh and remote environment. Wax deposition is a significant flow assurance issue for the oil and gas sector because it may impede and subsequently block the formations, pipelines, and production facilities. As a result, the flow assurance problems must be addressed appropriately to ensure the cost-efficient production operations. The maintenance of operation facilities is a costly and time consuming newlinejob. The lower temperature of the pipeline in case of deep waters and ultradeep waters is responsible for crystallization and deposition of wax in the pipeline. Crude oils contain long-chain alkanes with high molecular weight and carbon chain gtC18. At the reservoir conditions, the waxes have fair solubility in crude oil. However, as the crude oil moves from the reservoir and drifts through the pipeline, the temperature decreases owing to loss of lighter fractions, cold surrounding and expansion of gases. Paraffin deposition begins below the Wax Appearance Temperature (WAT). The situation is exacerbated in subsea pipes, where water newlinetemperatures can drop up to 5°C. Wax molecules crystallise in the pipeline flow when they come into contact with the cold temperature of the pipe wall, which is especially common in subsea pipelines. The thicker crystallisation completely blocks the oil supply. Different methods viz. mechanical, thermal, and chemical or combination of any of these methods are generally used for inhibition and rectification of paraffin deposition in crude oil production systems. However, non-viability of mechanical and thermal methods in offshore production make chemical additives more prevalent. Thus, chemical methods are preferred for mitigation of wax deposition which include solvents, wax dispersants, surfactants, Wax Inhibitors (WIs) and Pour point depressants (PPDs). Among all the additives, chemical additives commonly known as PPDs are extensively used to remove wax build up.