Water Injection Systems Data Requirements

The following data is typically required in order to undertake a detailed surge analysis of a water injection system. The data that is relatively easy to assume has been marked with an asterisk (*).

Drawings

• Process and Instrumentation Diagrams.
• Isometric drawings detailing pipe lengths and elevations for all pipework.
• Flow Utility diagrams for all platforms (if available).

Pipework

• Internal diameters.
• Wall thicknesses.
• Pipe wall material type and its pressure rating, particularly any ability to accept negative pressures.

Booster and Injection Pumps and Pump Pipework

• Pump Head / Flow / Efficiency and Power / characteristics.
• Run up times, impeller diameters(*) and inertia’s(*).
• Pump pipework data (diameters and wall thickness).
• Automatic air vents on the risers (type, size and manufacturer).

Recirculation Valve / Test Lines
If recirculation lines are installed on the pump pipework, the following is required:

• Recirculation dump valve size for each pump.
• End to end stroke times.
• Proportional band and Integral Reset time (*).
• Flow / Pressure drop characteristics of any back pressure devices to valve.

Degassers

• Operating pressure.
• Operating levels.
• Vessel dimensions.
• Type and control mechanism for level or pressure control.

Filters

• Operating pressure.
• Pressure Loss (duty and soiled).

Injection Wells

• Operating pressure (flowing at what flow).
• Pressure at rest (well back pressure.
• Recovery time after flow stops.
• Dimension of injection well pipework, length, diameter and profile.
• Detail of well head valves (type, losses operating position etc).

Back Pressure Control Valves
Details of any control valves in the system, particularly any used to maintain positive pressures within the system.

Isolation Valves
Isolation valves may be installed throughout the system to allow isolation of any section. It is generally assumed that these valves will not be closed against pumped flow and typical valve characteristics can be assumed. If it is requested that the precise characteristics of these valves are modelled, the valve manufacturer and type details will be required.

Air Valves / Vacuum Breakers
If any automatic air valves or vacuum breakers are incorporated on the system (usually on high points), the following is required. Typically these might be required if any of the injection wells settle at low pressures or the system is frequently de-primed.

• Valve type and manufacturer (*).
• Valve size.
• Valve location and elevation.

Duty Flowrates and Pressures
The design duty flowrates, and the pressures that are expected throughout the system (this may be available from the UFDs).

Proposed Operation of the System
In order to obtain a clear understanding of the system operation and to be able to determine the worst case scenario’s, a description / clarification of the mode of operation of the system, including any automatic pump re-start or standby pump start logic, is required. For example:

• What are the maximum number of booster and injection pumps that can start into the system simultaneously, and what are the delay times between pumps. If a pump fails to start, what is the delay time for the next pump to be started?
• What is the maximum and minimum number of injection wells that can be on line simultaneously and how is their selection controlled?