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.

This paper presents an automated workflow that can estimate the oil and gas rates of a well, with the high frequency data, distinguishing the behavior of the reservoir under transient flow and pseudo steady state flow conditions. The new approach matches the wellhead pressure of a well model with the current value reported by a SCADA system, by adjusting the bottomhole pressure. For transient flow, it considers the response of the inflow performance relationship as a function of time. For pseudo steady state flow, it considers the declination of the reservoir pressure. The estimation of the production rate is carried out every 15 minutes, and the total daily produced volume is calculated based on the effective flowing time. To evaluate the accuracy of the new well rate estimation workflow, the output of the workflow is evaluated using two different criteria. Initially, the estimated oil and gas productions are compared with data from a real well test that is used as a quality control point. Secondly, considering that the fluid properties remain stable over time (water cut and gas-oil ratio), the critical flow through a choke valve defines a historical production trend that is used to quantify the deviation of the estimated values. As a result of the new workflow application, the difference between the estimated and measured rates decreased from 10% to 3%. The novelty of the new method is that it reduces the error of the estimated oil and gas production rates using the actual reservoir pressure behavior and provides more precise data for the different reservoir engineering analyzes.

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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.

The complex Jurassic fields consist of eight onshore fractured carbonate fields, producing from four different structures. In the reservoir, fluids are in critical phase. Three out of the eight reservoirs are volatile oil and the remaining are Gas-condensates with high H2S & CO2. Currently ~35 wells are connected to the Early Production Facility (EPF) and the well deliverability is just enough to produce at the facility design capacity. As per the development strategy more wells will be connected to the facility for Long term tests (LTT) and booking reserves. As per the current development plan, additional processing facilities will be commissioned in next 2 years. Over seventy additional wells will be connected to these facilities with the target to triple production. In order to achieve the targets of the Jurassic field development plan, a flagship DOF (Digital Oil Filed) program called KwIDF (Kuwait Integrated Digital Field) was deployed by instrumenting ~35 wells and developing 22 production surveillance and analytics workflows. These workflows encompass HSE, operations and engineering requirements of the asset. Phase-1 of this technology program was initiated in 2010 and deemed complete in mid-2012. Since then the maintenance and enhancements of the existing system was done by improving the workflows which assist in better management, decision making, field monitoring and operations. This paper describes the new workflows which were built over the last 3 years where automated calculations run every hour to estimate flow rates for Oil, Gas, Water, H2S & CO2 based on combining real time well data and steady state nodal analysis models. The blended API workflow tracks the crude API density at the outlet of the Early Production Facility (EPF) and helps to prioritize wells to be connected to meet the target crude density. Similarly the H2S & CO2 monitoring workflows calculate the daily average H2S & CO2 rates and its percentage. These workflows along with the choke sensitivity workflow helps to optimize the production with the H2S & CO2 constraints. With the expansion of the field, a technology upgrade is also being planned under a Jurassic KwIDF Phase-2 program. The technical design of KwIDF Phase-2 was completed on April 2015 and the new workflows to be developed have been identified. The new workflows will focus to improve the well performance monitoring, Virtual Flow Metering (VFM), Surface – Subsurface integration, Choke Management, hydrate control and well & pipeline integrity.