Assuring Optimum Production and Enhanced Operational Efficiency through Transient Simulation: A Case Study in North Kuwait Jurassic Fields

Abstract

The paper presents the flow assurance challenges and the mitigation steps taken in the deep, high pressure & high temperature North Kuwait Jurassic (NKJ) Fields. Flow assurance is extremely diverse subject linked to different engineering disciplines. Understanding the reservoir fluid behavior, rock minerals, completion & pipeline metallurgy and operating envelope is critical to understand and overcome the flow assurance challenges. Pipeline Hydrate Formation is the biggest operational challenge, which frequently disrupts the production of some of the high producing gas wells during the winter months. Different chemicals and combinations of such have been attempted to mitigate the hydrate problem, still optimization of the chemical injection process is ongoing. Other problems of solid, scale or salt blockage in the tubing, surface chokes and pipelines have occurred and steps were taken to clear the obstructions. The NKJ fluids are highly corrosive and a corrosion inhibitor is injected at the wellhead to protect the surface pipelines. Addressing all these challenges require thorough knowledge of the specialized subjects and advance modeling to improve the field operational philosophy. In the NKJ fields, the pipeline connecting the well to the processing facility (5 – 30 Km long) are neither buried nor insulated. During the winter months (during night & early morning), the well fluid cools down below the hydrate formation temperature in the flowline causing hydrate crystallization and even plugging of the pipeline. Out of the 30 producing wells in the NKJ fields, half of the wells produce water and have hydrate tendency. The produced water salinity varies from well to well and range from fresh water to highly saline water with salinity as high as 330 kppm. This makes the system highly complex and manifest need for a robust solution. The paper walks through the traditional methods of hydrate mitigation done in the NKJ fields and the way in which transient model was initially built and continuously improved with more data. Currently methanol is used as the hydrate inhibitor and an anti-agglomerate (AA) is under trial. The methanol concentration is governed mostly by experience and on a reactive mode. An offline transient model advisor was built to understand the hydrate mechanism and optimize the methanol injection The advisor is still under trial, once simulation matches with the field conditions, then it will be online and linked to the existing KwIDF (Kuwait Integrated Digital Fields) technology program. Under KwIDF, Chemical Management workflow will be designed to optimize methanol injection to minimize the well downtime and reduce the OPEX cost. The transient advisor also can predict the surge at the facility inlet which can assist in balancing the production in and out of the facility.