WO2011099888A1

WO2011099888A1 - Inflow control device for a production or an injection well

Info

Publication number: WO2011099888A1
Application number: PCT/RU2010/000430
Authority: WO
Inventors: Andrey Vladimirovich Shishov
Original assignee: Limited Liability Corparation "Whormholes"
Priority date: 2010-02-15
Filing date: 2010-08-03
Publication date: 2011-08-18
Also published as: WO2011099895A3; WO2011099895A2

Abstract

We developed the device, which can provide a gradual increase in hydraulic resistance against moving fluid flow, and hence to a gradual reduction of the fluid pressure. This device can be designed for an operation with any type of flow: liquid, gas and its mixture. The proposed devise is meant to equalize the flow or pressure profile in/out of the well for mining/flooding operation in oil production.

Description

Inflow Control Device for a production or an injection well.

The technical solution lies in the area of mining operations particularly in the area of flowing fluid to/from reservoir from/to wellbores. The technical solution can be used for control of mining fluid flow particularly of oil to the wellbore as well as for formation oil substitution (flooding). This solution can be crucial for heating the formation using additional injected flowing substances such as water, steam or water-steam composition. During this process the devices being used should provide close to homogeneous flow rate of the specified substance along the whole working area. The area length can be more than 100 incoming pipeline diameters.

In the known devices, in order to have a homogenous flow out/to the reservoir two input channels (inner and outer along an annular spacing) are usually used. In this case, the restrictors in form of nozzles made from ceramics are installed at the entrance to the annular spacing. The purpose of these restrictors is considerable pressure decrease (a few tenths of MPa) behind them. This is achieved by an extremely high flow rates around 50 - 100 m/s inside of ceramic inset. The devices based on this mechanism are usually operating well with fluid at enough differential pressure at the entrance with no risk of medium boiling, for instance.

In case if the differential pressure is not enough, then the local pressure drops below the saturation pressure. This leads to two-phase unsteady flow. Boiling and condensation of fluid and vapor correspondingly lead to rapid and significant change in the medium specific volume. This leads by-turn to the local acceleration of small drops to greater velocities and hence to an impact on the walls of the ceramic inset.

In particular, a device (patent US, 2009-0000787) is known that is applicable for the control of liquid flow coming to production tubing of the wellbore. This device represents a body with two end surfaces. The body contains inner and outer concentric tubular sections with a cylindrical area in between. This area is open at one end of the body and closed at the other end. There is a window in the inner tubular section, which is adjacent to the closed end. There is a wall between the first and the second ends of the body. This wall has an opening which is adjustable in size. The opening is designed for liquid communication from the one end surface to the other. In an embodiment of the device the described opening could have a variable pressure control valve. Besides, the relief valve could also be installed. In addition, the opening could optionally contain a movable latch which is able to overlap at least the part of opening for control of the coming liquid flow through the opening.

The disadvantage of the device described above is its complexity and low working suitability in case of substances different from liquids. The technical problem being solved by means of the proposed design is to create optimal conditions for mining the liquid underground resources, particularly oil. One of the technical results from the realization of the developed design is an increase in oil recovery.

The proposed devise is meant to achieve the stated technical result by means of control of the fluid flow coming into production or out of injection wellbore. This devise contains a preferably cylindrical body accompanied with the fluid flow inlet and outlet connected to a channels network located between the fluid inlet and outlet. The network can provide a gradual increase in hydraulic resistance against moving fluid flow. The gradual increase in hydraulic resistance leads to a gradual reduction of the fluid pressure.

Increase in hydraulic resistance can be realized by multiple changes of the direction of the flow, and/or by contraction and expansion, and/or by merging and splitting of the flow. In the preferable embodiment of the developed device all three variants of the hydraulic resistance growth can be used. This device can be designed for an operation with any type of flow: liquid, gas and its mixture (water, vapor and water-vapor mixture as well as for nonaqueous fluids). The device can be fitted to the same dimensions as used for ceramic insets. The developed device can be manufactured from any corrosion proof metal or metal alloy and also from ceramics. The device operation range of the flow velocities is by an order of magnitude lower than for ceramic insets.

The device performance is based on the following principles. It is known that the pressure drop is a function of flow rate:

ΔΡ = ξ p ω² / 2

where: ΔΡ - the pressure drop on the element of construction ξ — the coefficient of hydraulic resistance of the element of construction

p - the flow density, kg/m

ω - the flow velocity, m/s

The equation shows that the pressure drop is influenced the most by the change in flow velocity since it has a second power in the formula above. Hence the resistance or pressure drop increase according to a square dependence when the flow velocity changes due to reduction of channel cross section.

When pressure drops below saturation pressure a new phase appears, which can disappear again further in the flow (boiling and condensation) if quite big change of flow velocity takes place. Due to these phenomena the local flow velocities can grow drastically. This can increase by turn the local mechanical erosion of the channel walls. Therefore even a ceramic inset does not secure the situation.

In the developed technical solution a local flow velocity is in the acceptable limit (around 10 m/s) and the required pressure drop is achieved by non viscous increase of the coefficient of hydraulic resistance.

As mentioned above the coefficient of hydraulic resistance can be enhanced due to several phenomena. Hydraulic friction can be increased by a considerable enlargement of length of the operation area. Still this is not efficient in terms of weight and dimensions of the device. It is more preferable to increase the coefficient of hydraulic resistance by changing flow direction (turns), by contraction and expansion of the operation area where the flow first accelerates and then decelerates, and by flow merging and splitting.

Stability of the coefficient of hydraulic resistance at the operation time or the whole device characteristics are also ensured by the absence of sharp edges in the flow channels. Near sharp edges the local flow velocities are increasing drastically. This can lead to the phenomena described above with the same consequences. This also increases the velocity of abrasive particles which can change the flow tract geometry by erosion or wearing the wall surface. The coefficient of hydraulic resistance can change in this case consequently. For these reasons the sharp edges are proposed to be smoothed.

In case of the developed device a pressure drops gradually and regularly throughout the whole length which provides good flow mixing and smooth working process of the device itself.

It is preferable to have the net cross section area of flow channels to be between 0.1 to 100 of the cross section area of the flow input or output channels. The mentioned channels can be located at the same distance from the device axis depending on the required pressure drop value. In other words, they can be located in parallel to the device axis or at an angle to the axis. The device can be implemented with an ability to create a pressure drop up to 100 MPa.

The developed technical solution is illustrated in Fig. 1 and Fig.2 where the device cross section and the device without a cover are shown. The device contains a cover (1), a working are edges (2), channels network with smoothed edges (3), openings (4) and an inlet tube (5).

In case of injection of the fluid to the reservoir, the device operates in the following manner. A fluid flow enters the device by the inlet tube (5). Part of it comes to the working edges (3) through the openings (4). Then while passing through the channels network with a smoothed edge ends the flow passes through the working area. At this stage the flow loses a part of its pressure and comes in the next flow tract of the device.

The developed device allows creating a pressure drop up to 100 MPa at an optimal channels network location.

Claims

What is claimed is a:

1. The inflow control device for the fluid coming to production or injection tubing of the wellbore differs from others by a body with the fluid flow input and an output connected to the network of flow channels while the network is designed to provide a big hydraulic resistance to the flow.

2. The device in the section 1 differs from others by the mentioned channels which are designed with a multiple changes of fluid flow direction.

3. The device in the section 1 differs from others by the mentioned channels which are designed with a multiple contraction and expansion of the flow.

4. The device in the section 1 differs from others by the mentioned channels which are designed with a multiple merging and splitting of the flow.

5. The device in the section 1 differs from others by the flow inputs and outputs which are made annular.

6. The device in the section 1 differs from others by channels edges which are made rounded.

7. The device in the section 1 differs from others by that the net cross area section of the channels lies from 0.1 to 100 of the flow input or output cross section areas.

8. The device in the section 1 differs from others by the fact that the channels are located in parallel with the longitudinal device axis.

9. The device in the section 1 differs from others by the fact that the channels are set at an angle to the longitudinal device axis.

10. The device in the section 1 differs from others by an ability to create a pressure drop up to 100 MPa.