Influence of Temperature on Wax Deposit on Corrosion of Crude Oil Pipeline

Nnorom Obinichi,Tolumoye Johnnie Tuaweri,Alexander Nwachukwu Okpala

doi:10.11648/j.ajmme.20210502.12

Abstract

The paper aims to study the effect of temperature on wax deposition on corrosion of crude oil pipeline at different flow rate with time. The waxy crude oil sample is pumped into the design and fabricated experimental flow-loop set up under different operating conditions. The effect of temperature on corrosion at different flow rate of wax deposition during the corrosion inhibition were studied at flow rate of 10.21, 20.37, 30.45, 40.28 and 50.70 L/min and time at 3, 6, 9, 12, 15 and 18 min while keeping temperature constant for each of the experimental run at 15, 20, 25, 30 and 35°C, to determine the corrosion rate against time. The results showed that at flow rate of 10.21 L/min and time 18 min at constant temperature of 15°C, the corrosion rate is 0.11 mpy. At flow rate of 10.21 L/min and time 18 min at constant temperature of 20°C, the corrosion rate is 0.08 mpy. At flow rate of 10.21 L/min and time 18 min at constant temperature of 25°C, the, corrosion rate is 0.12 mpy. Based on the results, a significant reduction of corrosion rates and excellent corrosion protection is achieved while others provided only moderate or negligible protection to the crude oil pipeline. However, the wax layer becomes thicker with time, if the temperature stays below the WAT for extended period of time and can in the long run, cause partial or total blockage of the pipe. Hence, as the deposition of the paraffin wax increases the corrosion rate decrease. The paraffin wax film presence on the surface promotes a significant reduction of general corrosion rates on the pipeline, although localized corrosion was observed due to loss of integrity of the paraffin layer. It means that deposition of paraffin wax inhibit corrosion and also give protection to the pipeline layer. Finally, due to the long chain paraffin layer being physically removed from the surface most of the corrosion protection has been lost during the periods of increased flow rate or temperature.

Highlights

Paraffin wax deposition is one of the long standing problems in the oil industry, Crude oils often contain paraffin which precipitate and adhere to the tubing, sucker rods, liner and surface equipment as the temperature of the producing stream decreases in the normal course of flowing, pumping or gas lifting
Based on the results of table 1, at flow rate of 10.21 L/min and time 18 min at constant temperature of 15°C, a significant reduction of corrosion rates and excellent corrosion protection is achieved while others provided only moderate or negligible protection to the crude oil pipeline
The wax layer becomes thicker with time, if the temperature stays below the wax appearance temperature (WAT) for extended period of time and can, in the long run, cause total or partial blockage of the pipe

Summary

Introduction

Paraffin wax deposition is one of the long standing problems in the oil industry, Crude oils often contain paraffin which precipitate and adhere to the tubing, sucker rods, liner and surface equipment as the temperature of the producing stream decreases in the normal course of flowing, pumping or gas lifting. Heavy paraffin deposits are undesirable because they restrict the production rate from the well and reduce the effective size of the flow conduits [1]. Where severe paraffin deposition occurs, removal of the deposits by thermal, mechanical, or other means is required, resulting in costly down time and increased operating costs. Treatments designed to remove waxy deposits significant operating costs are incurred from production tubing or squeeze treatments designed to inhibit wax deposition [1]. The costs are increased further by formation damage and loss of production that may result from these treatments. Some of the problems caused by these deposits are related to flow restriction, which leads to pressure increase in the flow line, decrease in production, and problems of mechanical [2]

Methods

Results

Conclusion