Abstract
Wax deposition is one of the major problems for onshore and offshore crude oil production. High molecular weight wax (HMWW) is commonly defined as a wax containing more than 40 carbons in its chemical structure. These types of wax are challenging to treat, as they form hard deposits that can be difficult to remove. Most paraffin inhibitors available in the market currently are not effective at inhibiting the formation and deposition of HMWW in oil production systems. This paper discusses extensive work on understanding HMWW characteristics and chemical methods to treat such deposits. A variety of wax characterization techniques, such as cold finger (CF), differential scanning calorimetry (DSC), cross polarized microscopy (CPM), and high-temperature gas chromatography (HTGC), were used to study the impact of inhibitor chemistry on wax characteristics.
Oil from South Texas with high wax content (8%) was evaluated using five different types of inhibitor chemistry. DSC and CPM were used to obtain the wax appearance temperature (WAT), and CF was used to deposit the HMWW and evaluate inhibition efficiency. HTGC results were obtained from the wax collected from CF to determine carbon distribution of the deposit. DSC of the wax was also performed to obtain the crystallization of the wax and estimate the wax content in the deposit.
Of the five chemistries evaluated, one showed good performance, with approximately 30% inhibition, while two polymers reduced the crystallization temperature and softened the wax deposit. The other two chemicals did not show any effects on the HMWW.
