Correlating Sour Gas Testing with Successful Field Operations of High Strength Quenched and Tempered Coiled Tubing

Abstract

Inhibition is considered critical to successful operations using high strength quenched and tempered coiled tubing in sour environments. Prior laboratory test results did not correlate well with initial field successes in Western Canada. The objective of this paper is to provide further testing that more closely matches real world applications and to provide additional field results from Western Canada. Similar to prior work in Elliott et al (2022), the overall approach to this paper is twofold. The first part focuses on C-ring testing of quenched and tempered tubing to provide confidence, coiled tubing will not fail due to sulfide stress cracking (SSC) when properly inhibited. Testing was performed with a limited exposure time to account for the short window for CT operations and a reasonable inhibition effectiveness period. The second portion of the paper discusses best practices for coiled tubing operations in sour wells. Laboratory C-Ring test results will be provided showing the effectiveness of the inhibition program as well as discussing the possible outcomes of utilizing coiled tubing in sour wells without inhibition based on the tests performed without inhibition. Discussion of the laboratory results will also describe the lessons learned in test plan development with respect to inhibitor effectiveness windows. Following the practical best practices for sour well CT operations, the paper will also discuss field history of quench and tempered coiled tubing building on the initial trials reported in Elliott et al (2022). The paper will conclude with a qualification for each grade of quenched and tempered coiled tubing when used with inhibition for sour operations. This paper expands upon the learnings of Elliott et al (2022) with testing program results that matches the field history of effective inhibition systems for high strength quenched and tempered coiled tubing in sour wells. This publication also explores the effects of sour exposure without the aid of inhibition, which serves to document the risks of forgoing inhibition in sour operations.