Whilst significant efforts have been made worldwide on developing solutions for capping offshore blowouts, less has been done to ensure safe and reliable kill operations through a relief well. This paper presents new solutions to challenging kill operations.Well-kill operations through a relief well are still considered the most reliable and ultimate method for killing a blowing well. Strict legislation has been enforced for such operations, which challenges technical operational limits and margins. The requirement to be able to dynamically kill a blowing well through one single relief may restrict well design and thereby reduce contingencies.By pumping of ultra-high density kill fluid (UHDKF) or by injecting a slug of UHDKF as part of a staged well-kill operation, more reliable operations can be planned for with reduced pumping pressures, reduced horsepower requirements, significant fluid volume reductions and cost reductions. Furthermore, these ultra-high density fluids can enable kill operations that would otherwise require changes to the original well design.Some ultra-high density kill fluids have been formulated based on high density cesium brines. A clear brine with a density of 3.20 g/cm 3 and very low viscosity has been formulated by blending cesium phosphate and cesium tungstate brines. Higher densities can be achieved by adding a small amount of solid weighting material to cesium brines.The new ultra-high density kill fluids represent a great technological step. It is recommended that the findings presented in this paper are implemented in future Blowout Contingency Plans in order to ensure sufficient operational margins in the relief well planning and the kill programs.

Breakthroughs of water and/or gas in production wells may have direct consequences for the production rates and overall field recovery factors. Multiple technologies have recently been developed to autonomously control inflow from the reservoir. Common to all these technologies is that new limitations are introduced which may have a negative impact on the well. This paper presents the design process for the next generation inflow control system and introduces new requirements for such completions. Traditional Passive Inflow Control Devices (ICD) are designed to act in a preventive manner by setting up a somewhat more even inflow profile along the reservoir section and thereby delay the breakthrough of gas or water. More recently, several new initiatives have been presented which will operate autonomously and try to choke back unwanted production. Common to all these technologies is that viscosity differences are used to identify the flowing fluid phases. Viscosity differences between the reservoir fluids are therefore mandatory for these to work. In this work the design process has been given an operational focus and the following requirements for the next generation autonomous inflow control devices have been defined: easy to install as an integrated part of the downhole completionrobust in design and functionalitysecures complete clean-up of mud and completion fluidsindependent of fluid viscositynegligible pressure drop during normal productionallows back-flow of fluids In this paper a new design is proposed for the next generation autonomous inflow control valve which is independent on differences in fluid viscosities. The proposed valve blocks, or restricts, production of unwanted water or gas, and re-opens for production if oil comes back. It can be designed to stop water/gas production at a predetermined WC/GOR. Furthermore, the valve ensures efficient clean-up along the full length of the reservoir section and is insensitive to exposure to mud, particles and filtercake. The valve will not restrict any future well operations and can be designed with a fail-safe option. The new design of autonomous inflow control systems represents a great technological improvement which will ensure robust, economical and fail safe design as well as removal of typical operational envelopes necessary for traditional technologies.

Subsea production of oil and gas involves structures on the seabed such as manifolds and X-mas trees that require thermal insulation of piping and valves to avoid gas hydrate formation. The insulation is expensive and time consuming to apply yet may still leave areas with inadequate protection. These “cold spots” accelerate the cooling during a production shutdown. A Heat-Bank concept is developed as an alternative to conventional insulation. The entire subsea structure is covered with an insulated shell. During shutdowns the heated fluid inside the cover keeps the production equipment warm over a prolonged period before hydrates start to form. Computational Fluid Dynamics (CFD) simulations are used to quantify the heat loss effects of natural convection and leakage through openings in the cover. The CFD analyses demonstrate the relative performance of the concept compared to the traditional method of insulating individual piping components. Application of the Heat-Bank concept opens new possibilities for environmentally friendly and cost-effective field development, especially for deep water.

Conventional ICDs were invented for long horizontal wells to promote a more uniform inflow profile. Later, AICDs were developed, which utilize viscosity contrast between fluids to impose a larger hydraulic resistance in sections with inflow of undesired fluids, like gas and water. However, these AICD technologies cannot be used to choke back inflow of water in reservoirs where oil and water have similar viscosities, and they also tend to impose large pressure drops even for single-phase oil at high flow rates. The objective of the work presented here has therefore been to develop an inflow control technology that removes these limitations. The resulting Density Activated Recovery (DAR™) technology utilizes difference in fluid density rather than viscosity contrast to control fluids downhole. It is a fully autonomous, binary system that is either fully open or closed, where "closed" means that it only allows a small pilot flow. More specifically, it can be considered a "dual ICD" with flow through a large port when open, and a small port when "closed". The flow capacity and choking efficiency are therefore fully defined by the diameters of these two ports. Furthermore, it can close and reopen at any pre-determined water and gas fractions, that are completely insensitive to flow rate, viscosity and Reynolds number. This makes it universally applicable to control any wellbore fluid along the entire reservoir section. After successful prototype testing in 2018, the DAR technology has now undergone a comprehensive full-scale system-qualification program including a final flow performance test where the system was tested at 240 bar and 90ºC with saturated 0.8 cP oil. The tests demonstrated up to seven times higher flow capacity with the density-based DAR technology compared with viscosity-dependent AICD technologies. The system successfully and repeatedly closed and reopened for both gas and water. As oil and water had similar viscosities, the tests also proved how this technology can be used to stop undesired inflow of water in light-oil reservoirs. Being insensitive to flow rate, the DAR system is also insensitive to local variations in pressure and productivity along the reservoir section, which reduces the negative consequences of geological uncertainty and allows the same design to be used at every location in the well. It can also be configured to ensure complete mud removal during well cleanup and can even stop inflow of water in gas wells, where the undesired fluid has higher viscosity than the desired fluid. More importantly, this technology can deliver automated reservoir management to a level where it influences how wells are drilled and fields are developed. Accelerated oil production and the reduced need for reinjection of gas/water will also reduce the associated greenhouse gas (GHG) emissions considerably.

Breakthroughs of water and/or gas in production wells may have direct consequences for the production rates and overall field recovery. Multiple technologies have recently been developed to autonomously control inflow from the reservoir. Common to all these technologies is that new limitations are introduced which may have a negative impact on the well. This paper presents the design process for the next generation inflow control system and introduces new requirements for such completions. Traditional Passive Inflow Control Devices (ICD) are designed to act in a preventive manner by setting up a somewhat more even inflow profile along the reservoir section and thereby delay the breakthrough of gas or water. More recently, several new initiatives have been presented which will operate autonomously, with an ambition to choke back unwanted production. Common to these technologies is that they are primarily dependent on viscosity differences between the reservoir fluids. In the work presented in the following, the design process has identified the following requirements for the next generation autonomous inflow control system: • easy to install completion • robust in design and functionality • Improve clean-up of mud and completion fluids • independent of fluid viscosity • negligible pressure drop during normal production • allows back-flow of fluids In this paper the results from an ongoing development of a new design inflow control system, independent on differences in fluid viscosities is presented, which fulfills above requirements. This system is based on a valve, which blocks, or restricts, production of unwanted water or gas, and re-opens for production if oil comes back. It can be designed to stop water/gas production at a predetermined WC/GOR. Furthermore, it ensures efficient clean-up along the full length of the reservoir section and is insensitive to exposure to mud, particles and filter cake. The installation of this system will not restrict any future well operations and it can be designed with a fail-safe option. The new system represents a great technological improvement which will ensure a robust, economical and fail safe design as well as a simplification of inflow design process, since it will work irrespective of local productivity, pressure and flow rate. Hence, removing the operational envelopes on which other technologies must be designed for to be able to work properly.