Challenges in Setting Cement Plugs in Deep-water Operations

Abstract

Abstract Offshore cementing poses many challenges across the world as drilling operations move towards deep-water and ultra-deep-water. As a new initiative of continuous improvement, a deep-water cementing peer review process was started early 2011. To this date, this team has reviewed more than 1200 deep-water cementing jobs in more than 30 countries worldwide. Plug cementing makes up nearly 53% of all the deep-water jobs reviewed. The majority of the cement plugs placed are for plug and abandonment purposes; however a significant part is for loss circulation, kick-off, or squeeze. Although plug cementing comprises a big portion of deep-water cementing, it often does not get the same level of attention as primary cementing. Specialized plug cementing software is used to design all cement plugs set in deep-water operations. The software simulates fluid interfaces, contamination during placement (both when the fluid is travelling down the pipe and when it is being placed in the annulus) and while pulling out of hole. As a final result, it provides the top of uncontaminated cement. Aside from proper job placement, good slurry design is very important. Cement slurries used for plug cementing need to be designed according to the objectives of the job. Several case histories will show lessons learned from the analysis of plug cementing operations in deep-water operations. As the industry and local regulations gets more stringent on the evaluation and acceptance of the barrier for well integrity, the success of setting a cement plug the first time is becoming ever more critical. Getting it right the first time easily saves several days of NPT resulting in savings of millions of dollars, especially in this deep-water environment. Appropriate focus on sound engineering practices and the use of the specialized software has improved reliability of setting cement plugs in deep-water and helps operators avoid costly remedial operations.