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Inflow Сontrol Technology
Inflow Сontrol Technology


In order to optimize the productivity of production wells and increase the oil recovery factor, inflow control devices (ICD) are widely used in world practice. For the first time, this type of device was used by Norsk Hydro (now Statoil) in the early 1990s to prevent early water breakthrough in extended horizontal wells.

In fact, inflow control devices are designed to solve the following main tasks:

·        Create a uniform fluid inflow along a horizontal well. Preventing cone formation effect in oil reservoir and the possibility of premature breakthrough of gas or water.

·        Effective blocking of water and gas breakthroughs.

                                               ·        Using the method of steam gravity drainage.

These factors of unequal inflow and threat of water and gas breakthrough reduce the productivity of wells, their service life, and can also lead to significant costs associated with the restoration of well-functioning after a breakthrough in water and gas.

Operating principle:

Inflow control devices are divided into:

·        ICD – passive inflow control devices

·        ICV -  inflow control valve (active devices)

·        AICD – autonomous inflow control devices of the first generation

·        AICV - autonomous inflow control valves of the new generation

The passive ICD inflow control devices mainly solve the problem of equalizing the inflow along the well. In fact, these devices create additional resistance in the flow of produced fluid, allowing to equalize the distribution of inflow along the well. Passive inflow control devices are used in the composition with sand screens, limit the flow of fluid that occurs when passing from the screen to the base pipe. Such a restriction is usually realized in devices in the form of narrow channels or nozzles, helical channels, nozzles / orifices. Typically, these types of devices are divided into two main groups: a low inflow rate (below 50 m / s) and a high inflow rate (below 50 m / s). Nozzle and channel ICD are used for high-speed modes, screw for low-speed.

In most cases, a turbulent flow regime is realized in the ICD, in which the flux depends on the density and depends little on the viscosity of the fluid, the flow value depends nonlinearly on the pressure drop. This dependence results in the device having greater effect of flow resistance with increasing pressure drop with respect to the variant without ICD, which somewhat equalizes the fluid flow along the well. For low-speed ICD, the forces of fluid viscosity are used to organize additional resistance, which have an effect in the case of using long screw channels. Adjustment of the parameters of these devices allows to align the inflow along the well and thereby prevent the premature formation of a strong breakthrough of gas and water.

Another version of the inflow controllers are active ICV devices with a switch or valve that is operated remotely by a hydraulic, electric or electro-hydraulic mechanism. ICVs are used to actively control the flow at different completion intervals. In practice, this type of device is used in conjunction with swellable packers that separate independent segments of the horizontal barrel to effectively regulate the inflow of different segments of well. There are variants of multi-position inflow control valves, which are switched using a sliding sleeve of the device. To operate these devices, special shifting tools are required to remotely switch the inflow modes. Devices of this type can effectively control the inflow of fluids along the well.

Disadvantages of this type of device is:

·        A expensive implementation of the inflow control device.

·        In this case, additional inflow control over the well segments is required, which is associated with additional costs.

·        A special shifting tool is required to switch the active inflow device, which also complicates the overall design.

Recently, intelligent or autonomous control devices for the inflow of AICD, AICV have been developed. The main feature of these types of devices is the more complex nozzle or valve design of the device. These devices effectively solve the problem of gas or water breakthrough into the well, since they react differently to the flow of oil, water and gas. Different technologies can be used to design the devices. The most common version of this type of device is a valve that implements a constant flow of fluid over a wide range of depressions to the valve. The flow rate depends on the viscosity of the fluid. Independent flow control devices can be called intelligent devices because the valve, passes only the oil and is blocked by the flow of water and gas, that is, reacts to the viscosity of the fluid. In this way, autonomous inflow control devices can effectively prevent the breakthrough of a non-productive fluid.

Advantages of using AICD of a new generation:
Autonomous inflow control devices AICV has the following advantages in solving the problems of managing fluid inflow in the well:

·        Allow to cover 98-99% of the breakthrough of water and gas into the well

·        Do not require external and remote control

·        The device restores the flow of oil after blocking the breakthrough of water or gas

·        There are no restrictions on the number of zones in the well on which the device can be installed

·        Can be installed for new and retrofitted wells

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