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Abstract

Ensuring good casing integrity is very important to prolong well life. Cement quality is a major element for ensuring casing integrity. Well casing integrity excellence is the key aspect that makes a well in good condition and keeps the well completion suitable to produce crude oil from an oil producer or inject water in an injector.

Recently, advances in cement and well completion practices have significantly improved the quality of wells and extended their operating life. Also, the installation of a Cathodic Protection System (CPS) on every well, and tubing packer completion in some wells, prevented external corrosion and consequently casing failure. However, casing integrity problems were discovered in three isolated cases. This paper will discuss issues related to three wells where casing leaks or behind casing channeling were detected across a high-pressure zone located above the main reservoir. A team, consisting of professionals from various engineering departments, was formed to explore remedial options and techniques, as well as employ tools and new technologies that assess well casing integrity excellence. Implementing the recommendations and findings of this team have improved well casing integrity.

As well casing is an important asset to ensure well safety, continuous operation and environmental protection; there is an ever increasing need for tools that verify wells with suspect casing integrity problems. These tools are the Cathodic Protection Evaluation Tool (CPET), Ultrasonic Inspection Tool (USIT), Ultrasonic Corrosion Inspection Tool (UCIT) and the Electro-Magnetic Imaging Tool (EMIT). The EMIT provides real images of the multiple casing strings.

CPET, USIT, UCIT and EMIT were selected and run on three wells Well-A10, Well-A20 (oil producers) and Well-B1 (water injector) with suspected casing integrity problems. These logs detected and imaged the corroded, scaled and cracked intervals before performing remedial actions to return the wells to an operating status by renovating casing integrity.

Introduction

Best practices for cementing are well established; however, there remains the continuous challenge of effectively deploying these best practices. For multi-zone completions, where the cemented tubing annulus is the single means for zonal isolation, this becomes a critical goal. The desire to meet this challenge led to the creation of an integrated professional engineering community that both provides the methodology and initiates the inter-disciplinary communication necessary to improve well casing integrity and zonal isolation.