This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 30838, “Shell Appomattox Model-Based Operations From Design to Production: A Game Changer in Gulf of Mexico Deepwater Operation,” by Robert Tulalian, Shell, and Evan Keever and Ankur Rastogi, Kongsberg, prepared for the 2020 Offshore Technology Conference, originally scheduled to be held in Houston, 4–7 May. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission.
The complete paper discusses how large operations such as Appomattox in the Gulf of Mexico’s deepwater Norphlet formation can use an integrated dynamic simulation-based solution throughout the project life cycle to aid in design verification, operator training, startup support, and real-time surveillance. The authors write that their recommendations and findings can be applied to similar project implementation efforts elsewhere in the industry.
The Appomattox development spans Mississippi Canyon Blocks 348, 391, 392, and 393. Peak production rates are estimated to be approximately 175,000 BOE/D, with water injection planned for the future to support reservoir pressures. Appomattox includes a combined cycle steam system, using process waste heat to generate steam. This steam can be used to drive a generator, providing extra power for the facility. The Appomattox facility can be seen in Fig. 1.
A multipurpose dynamic simulator (MPDS) was developed to address the inherent complexities of the Appomattox system, providing a high-fidelity integrated model that simulates both top-sides and subsea process conditions. This model was integrated with the Appomattox control system and deployed in a setup to mimic the offshore control room, creating a realistic training environment for operators. The MPDS was completed over 1 year before first oil, providing ample time for operator training and other use cases such as distributed-control-system (DCS) checkout and engineering studies.
Because of the success of the MPDS, the operator applied the existing Appomattox model to the operation phase through the creation of a real-time surveillance system (RTS). Connecting the process model to the facility’s historian by open-platform communications (OPC) enables the RTS to serve as a virtual copy of the live facility, mimicking process conditions in real time. This enables the RTS to serve as a platform for useful surveillance applications such as virtual flow metering, blockage detection, and equipment-performance monitoring.
Once the decision to build an MPDS was made, the project team determined which systems would be included in the scope of the model as well as what data would be used for input and validation. Because the MPDS would be used for both engineering and operations use, most systems were included in the scope and modeled at high fidelity to maximize potential benefits.