The updates in the US code of federal regulations 30 CFR Part 250 Oil and Gas and Sulphur Operations in the Outer Continental Shelf, released in 2016, relate to, among other things, real-time well monitoring on critical well operations including cementing. The regulations do not assume that onshore-based staff would assume operational control, but rather that onshore expertise can assist the offshore location in determining anomalies before they become critical issues. Currently, cement job monitoring is often limited to the acquisition of pressure, rate, and density measurements. Based on those measurements, a basic evaluation is performed during the job. A new software tool has been developed to improve the ability to interpret and diagnose critical job parameters while the cement job is in progress. The real-time cement monitoring (RTCM) simulator combines data from the cement job design with acquisition data from the cement unit and rig to provide a detailed picture of the operation by comparing acquired values with predictions computed in real time. Data acquired during the cement placement are processed by a hydraulics simulator incorporated into the software to provide key information about the fluids' position in the annulus, comparative trends of acquired versus simulated surface pressures, density quality assurance and quality control, and real-time visualization of dynamic well security. Based on the real-time estimation of the fluids' position in the annulus and other key parameters measured during the job execution, a contingency plan can be followed, thus avoiding the need to wait on a detailed post-job analysis of the raw acquisition data. This paper describes the methodology of the software and how it helps to diagnose the cement barrier placement in deepwater wells. The real-time monitoring of the cement job starts with the evaluation of the pre-job circulation and ends with the final displacement. With the real-time capabilities, experts can remotely view operations and provide recommendations during the cementing operations and immediately advise on post-cementing rig activities. Through case studies from the Gulf of Mexico and Atlantic Canada, the process and benefits will be shown to improve barrier verification as early as possible in the well construction phase. The novelty of the software is that it can be used to diagnose the quality of cement jobs during the execution stage. Synchronized visualization of wellbore schematics showing fluids position, equivalent circulating density (ECD) progression, and combined measured versus simulated surface pressures are critical to help determine the position of fluids in the annulus and provide early verification of a barrier.