Technical Measures for Ensuring Storage Wellbore Integrity

Abstract

With the extension of the injection and production operation cycle, the phenomenon of an annulus under pressure in natural gas wells and injection and production wells in gas storage facilities has become serious in China. In view of this situation, in order to maintain the wellbore’s integrity, in this chapter, a series of wellbore integrity measures based on 20 years of gas storage construction experience in China is proposed, including thread tightness detection, casing running process measures, cement sheath post evaluation, wellbore sealing testing, wellhead equipment selection, and corrosion protection. Specifically, the hermetic seal test equipment and techniques for the threaded connections of DRGLI tubing and casing are developed. This chapter introduces the wellbore integrity of horizontal injection and production wells in terms of string integrity and outer cement sheath integrity. The specific steps involved in the wellbore safety pressure test, a series of measures for wellhead equipment selection, and successful practices in China are described. After several years of continuous research and field tests, six domestic gas storage facilities have developed targeted tubular product selection procedures and methods for different corrosive environments in various oil and gas fields.