Because all gas-lifted oil wells produce differently depending on gas injection rate, sharing injection gas across multiple wells efficiently is important to lift the most oil.  Any inefficiencies reduce production and increase lifting costs.  The aim is to reduce these inefficiencies as far as physically possible, and that is exactly what StarStream’s patented Cascade Injection Control does.

  • CIC will automatically distribute the lift gas in the most productive way.
  • CIC is directly applicable to gas-lift operations right now, and it is implemented quickly and easily.
  • CIC doesn’t require extra computing hardware, as the scheme is implemented within the existing offshore control system.

CIC increases production from gas-lifted oil wells by around 4-12% and effectively reduces lifting costs.

What CIC does is provide organisations with a business tool, like a new handle, to put them at the optimum economic operating point in real-time.

CIC will take production from the grey curve to the blue curve AND put the operating point at the best point for the business.

Organisations can balance production and cost savings on a day-to-day basis.

What does Cascade Injection Control improve?

  • Increased production from gas-lifted oil wells
  • Effects of gas flow constraints (compressor forward flow capacity)
  • Minimise fuel consumption
  • Reduced impact of unplanned process shutdowns
  • Control of well products e.g. sand production, N2, H2S4
  • Reduced control room management of gas-lifted well operation

Who is Cascade Injection Control (CIC) for?

For those operating gas-lifted oil wells offshore topsides or sub sea.

What does CIC do?

Automatically adjusts gas injection flow rates to gas-lifted wells in real-time, without operator intervention.  CIC ensures that every unit of gas is distributed in most production efficient manner.

Where is CIC used?

Gas injection process plant where compressed injection gas is discharged into a common manifold serving multiple gas lifted wells.  The control scheme can be integrated into the client’s existing control system.  No existing functionality is lost.  Manual control of individual valves can still be used (e.g. flow testing, taking the well out of service).

How does CIC work?

As gas flows into the common manifold, the patented CIC algorithm has the effect of relieving gas from the manifold via the gas injection flow control valves.  The CIC master controller balances the inflow and outflow to control the manifold pressure at a desired set-point.  Each gas injection flow rate is calculated using pre-set constants that describe the gas injection rate / oil production relationship for each well.  Therefore the amount of gas flow delivered to each well is the optimum amount based on the total amount the gas available.  This ensures that every unit of gas is distributed optimally at all times.  CIC is enabled and disabled by a single operator command with a bumpless transfer of control.  The CIC algorithm can calculate the optimum distribution for any number of wells considering any amount of available gas flow.  Individual well flow and pressure (high and low) constraints are also managed automatically, making the system very operator friendly.

When is CIC actually in use?

Constantly in real-time.  CIC automatically distributes available injection gas in the most optimal way for production in continuously varying process conditions.  However, no existing functionality is lost.  Manual control of individual valves can still be used for flow testing or taking a well out of service.

What improvements can the client expect from CIC?

Increased revenue and reduced operational expenditure by,

  • Increased oil & gas production from gas-lifted wells
  • Saved production during upsets and plant restarts
  • Reduced energy consumption
  • Reduced attention required by operators
  • Increased visibility of well performance
  • Enabling associated process plant to used more efficiently

What hardware does CIC require?

Typically CIC uses equipment already installed.  A manifold pressure measurement, an electronic control system, and actuated injection control valves are required.  The solution manifests as an enhancement within software.

How do I get CIC implemented?

Basic well information is compiled by the client and submitted to StarStream.  The information will allow StarStream to accurately calculate and quantify the improvements of using CIC bespoke to the asset.  This allows the client to assess CIC prior to developing and implementing the software for the process control system.

What happens if well performance changes?

As new individual well data is obtained it can be leveraged immediately by updating CIC to ensure complete optimisation.  New gas injection flow verses oil production curves are used to calculate new parameter values for CIC.  These values are entered directly into the control system.

Where has CIC been implemented?

CIC has been successfully implemented on two major UKCS producing fields.

How does CIC control within platform constraints?

Everything is tied back to gas lift injection rate limits.  The limits are adjustable and can be tied back to another measurement. e.g. if well injection pressure is a limit, it can be fed back into CIC such that it increases up to that constraint but no further.  Because of the smart way that CIC handles limits, CIC can be used to control any undesirable component (water, H2S, sand etc).  When CIC reaches a limit it automatically redistributes that gas to the rest of the unconstrained wells in the most productive way.

Are their any limitations in terms of compatible control systems for interfacing?

CIC is unique in that it only uses normal mathematical operators to calculate an explicit answer (not iteratively converged upon).  This means that it can be implemented in even the most heritage of logic solvers without any extra hardware required.  Calculation cycles take less than 100ms.

How is CIC charged?

Annual per-well licensing.  This includes technical assistance and reporting through an online portal.