Scale Inhibitor Application in Northern Alberta: A Case History of an Ultra High Temperature Scale Inhibition Solution in Fire Tube Heater Treaters

Abstract

This paper reports a challenging and unique scale forming environment in Northern Alberta, Canada. Calcite was forming on the fire tubes in a series of treaters. Bulk fluid temperature was 110°C but skin temperature of the fire tubes was in excess of 450°C. This created an incredibly high scaling potential.The paper provides background on the field case history with a detailed description of the process and the scale forming environment. An in-depth scale modeling study characterizing the scaling up to 200°C is provided.Further laboratory studies are reported including performance testing on candidate scale inhibitors and differential scanning calorimetry to determine their molecular stability. The testing looked at scale inhibitors and investigated the direct inhibition properties as well as any dispersion properties to prevent surface adsorption of scale on the fire tubes.The testing found that the incumbent scale inhibitor (phosphonate based) was a good product for the bulk scale inhibition but was not stable at the temperature of the fire tubes. The most thermally stable scale inhibitors tested were polymaleic acid copolymers and polymeric acrylic acids of low to medium molecular weight. No scale inhibitors were tested to be fully stable up to 450°C but it was found in field application that the best product identified through laboratory testing was sufficient enough to delay the scale formation on the fire tubes. It is hypothesized that the product was stable at high temperature for the residence time of fluid in the treaters or imparted some degree of scale inhibition even after thermal molecular scission.The paper concludes with data of the fire tube change out history highlighting the step change in performance when applying the polymeric inhibitor quantified by change out frequency and presence of hot spots.

Polymer Flooding of Heavy Oil - From Screening to Full-Field Extension

“…Polymer precipitates on the fire tubes and causes hot spots which eventually lead to the tube failure (Bartz et al 2014); these failures can be frequent and increase operating costs. Wylde et al (Wylde et al 2011) correlated increased fire tubes temperatures to the increase in polymer concentration present in the effluents in Pelican Lake.…”

“…The development of new scale inhibitors for fire tubes (Wylde et al 2011) and modifications in fire tubes design (Bartz et al 2014) have successfully been used to alleviate these issues.…”

“…Due to the very large number of wells under polymer flood (relative to the total number of wells in the field) the concentration of polymer produced in the facility is high and has made separation issues more difficult (Wylde et al 2011).…”

Effect of Produced Sand Particles and Fines on Scale Inhibitor: A Review

“…Many chemicals such as organic phosphonates, organic phosphates, and low molecular weight ester derivatives of these molecules with desired secondary properties have been widely used as scale inhibitors in oil and gas applications [48]. Nevertheless, ongoing efforts are geared towards green scale inhibitors such as polycarboxylic acids and polyacrylates and their copolymers, which are eco-friendly [41].…”