Strömungsberechnung

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Flow Calculation to determine Pressure Losses

Calculation for:
Oyong Oil and Gas Field

Introduction

The most advantageous conditions to produce a viscous media out of a reservoir would be to have an open hole drilled into the reservoir without any flow restrictions. Therefore, the first and most important criteria for a high and feasible exploitation should be to complete a well project into the producing zone with as little restrictions as possible.

The higher the permeability of the sands in the reservoir is, the higher should be the inflow capacity of the sand and flow control media: the well screen. Any type of screen structure is a permeable media through which the flow penetrates under certain hydraulic conditions. Therefore, it is of mayor importance to determine the permeability of the screen used for the completion. Because, the permeability is the true indicator of the inflow capacity and of the interface with the formation, not the open area being only part of the screen structure. The permeability is 3-dimensional; the open area is only 2-dimensional. Therefore, the screen permeability should be the comparison criteria for all screens offered to this industry, not the open area.

The following calculation form allows the dimensional determination of the screen structure:
The diameter and the length of screen required or the flow conditions (laminar, transistant or turbulent) for a determined screen length.

It is anticipated that this information is for a stand-alone Rod Based Wire Wrapped Screen without a base pipe, thus improving tremendously the flow conditions and interface between the Screen interior and the reservoir formation.

This calculation allows the user to optimise operational conditions of his well project. 

Objectives & Inflow Criteria

The screen structure is determined by

- the surface profile,
- the support rods and
- the amount of support rods on the inner circumference of the screen.

The screen structure determines the mechanical strength of the screen body and thus all installation criteria.

con-slot® has developed a stand-alone screen without a base pipe to be handled during installation proceedings like a casing or tubing, yet the permeability has been proved to be extremely high!

The slot size is determined by the sand analysis of the formation based on certain selection criteria like percentage retained, uniformity coefficient etc. The screen diameter is determined by the borehole diameter which depends on the formation permeability and thus the productivity rate to be expected. The screen length is determined by the required penetration of the reservoir and the formation permeability as well as the productivity rate to be expected.

The following calculation will assist in the well balanced flow characteristics of a completed well, whether vertical, inclined or horizontal.

Production Data

Flow 1

Calculation of Screen Permeability

Flow 2

Flow 3

Flow 4

Critical Entrance Velocity

Flow 5

Flow 6

Summary of Pressure Losses

Flow 7

Final Comments

The permeability of the screen is high in comparison to the permeability of the reservoir formation thus indicating high reserve of flow capacity! The entrance losses into the screen are so low that it can be practically neglected.

The total pressure loss of the ‘Stand Alone’ Screen is only 0,329 bar (4,763 psi) with a flow capacity of 3500 BOPD.

This indicates that the flow capacity can be increased to more than a double thus showing clearly the advantages of a ‘Stand-Alone’ con-slot-screen®.

Alteration of the conditions by repeated calculation can give you a fast and satisfactory answer to your tasks. You only have to join in!

However, it should be made clear that these conditions can only be reached, if the return permeability from the formation is re-established at its best. Here the advantageous permeability of the screen with its excellent ‘formation linkÔ pattern gives you the possibility to do better clean-up jobs than with any other screen on the market.

Stimulation by impact waves from inside the screen into the formation will improve permeability, stabilization of the formation surrounding the borehole for the life-time of the well.

Reduced water-coning, improved productivity will be the consequences you cannot neglect!

Friction Factor (S1) of the slot opening

Flow 7a

Friction Factor (T) of the Screen Pipe Structure

Flow 8b

Screen Testing Unit

Flow 8

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con-slot SCREENS | Industriegebiet Hafen | Graue Riethe 2 | D-29378 Wittingen
Tel: +49 5831 2515-0 | Mail: info@con-slot.de