Flow Assurance

Wax or paraffin formation in subsea pipelines is a major problem in the upstream petroleum industry, accounting for tremendous economic losses. Researchers have reported that approximately 85% of the world's oils encounter problems from wax formation (Thota and Onyeanuna 2016). In this manuscript, the authors briefly discuss the mechanism of wax formation in pipelines. Next, a review of various wax-mitigation technologies is provided. The review includes citations of various thermal, chemical, mechanical, biological, and other innovative methods reported by previous researchers and used in the industry.

The present study investigated the wax deposition tendencies of a light Malaysian crude oil (42.4° API), and the wax inhibiting potential of some surfactants and their blends with nanoparticles. With the knowledge that the majority of the wax inhibition research revolved around polymeric wax inhibitors, which cause environmental issues, we highlighted the potential of surfactants and their blend with SiO 2 nanoparticles as wax deposition inhibitors. Different surfactants including oil-based, silane-based, Gemini and bio-surfactants were considered as primary surfactants. The primary surfactants and their respective blends at a concentration of 400 ppm were screened as wax inhibitor candidates using cold finger apparatus. The screening results showed a significant influence on the paraffin inhibition efficiency on wax deposition by using 400 ppm of silane-based surfactant, which decreased the wax deposition up to 53.9% as compared to that of the untreated crude oil. The inhibition efficiency among the silane-based surfactant (highest) and bio-surfactant (lowest) revealed an appreciable difference up to 36.5%. Furthermore, the wax from the treated sample was found to deposit in a thin gel-like form, which adhered inadequately to the surface of the cold finger. A further investigation by blending the 400 ppm silane-based surfactant with a 400 ppm SiO 2 nanoparticle suspension in a load ratio of 3:1 found that the wax inhibition decreased up to 81% as compared to the scenario when they were not added. However, we have shown that the synergy between the silane-based surfactant and the nanoparticles is influenced by the concentration and load ratio of surfactant and nanoparticles, residence time, differential temperature and rotation rate.

Hydraulic performance and thermal characterization are the main parameters dictating proper consideration of flow assurance in pipelines. Hydraulic performance considers the evaluation of multiphase systems, specifically the equilibrium of phases and consequent flow patterns and their impact on pressure loss, holdup and sustainable and safe flow transport characteristics. Secure supply of hydrocarbons via pipelines plays crucial importance to maximize their production. In this study, a multiphase flow simulation of gas-condensate is developed using PIPESIM TM software. The data and main physical parameters correspond to a projected offshore natural gas pipeline located in the north sea of Venezuela. The flow of hydrocarbons is analyzed and potential improvements are presented using both a traditional single-size and an¨out-of-the-box¨multi-sizing technique with the objective to reduce predicted overall holdups and pressure drops along the pipeline. The simulation permitted to assess different flow characteristics as liquid holdup, flow rate and pressure drop through different sections and accessories of the pipeline. Fixed pipeline insulation was maintained along all the study to keep a practical number of independent variables. The outcome of the analysis demonstrates that with a reasonable adjustment of pipe diameter, it is possible to increase the gas production without extra energy to compress the line, favoring the project economy and reducing its carbon footprint.