APC for Wellhead Chokes to Optimize Plant Performance in Tengiz Field

Tengizchevroil (TCO) has implemented Advanced Process Control (APC) to automatically control the feed into the plant by adjusting the chokes of selected wells in the field. The automated choke operations are closely monitored and thoroughly discussed during daily Field-Plant interface meetings to confirm overall stability of the plant performance and improvement in plant efficiency. With the use of a dynamic multivariable model-based controller we are now able to predict the demands from the production facility and automatically deliver the exact amount of field production to meet plant's ever-changing production capabilities while minimizing the pressure losses between the field and the operating plant. The early APC deployments demonstrated the opportunity in delivering highly significant value to TCO. TCO had implemented numerous APC throughout the plants to optimize complicated processes and developed the necessary organizational capability (OC) to implement the Field APC. The Field APC project was the first joint project involving both the field and the plant assets. This APC project demonstrated the "One TCO" approach, with support and buy in from a cross functional team of Automation, Reservoir Management, Process Engineering and Plant Operations personnel. TCO is now able to automatically react to changes in both the field and plant to deliver the maximum plant capacity at any given moment. Since plant throughput limitations are constantly changing due to changes in ambient temperature, H2S content or gas-oil ratio (GOR) of the inlet feed, etc.; the APC is automatically adjusting the output from the wells to match the inlet requirements of the plants. The solution uses dynamic models to predict constraints and drive operations to an economic optimum while honoring an everchanging set of constraints. The APC allows the plant and field operators to spend more time addressing non-routine problems by automating one of the operator's routine duties.