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In case the bottomhole pressure data is not available it is considered constant over time.
Motivation
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Production rate in producing well depends on its productivity index
, current formation pressure LaTeX Math Inline body J
and current BHP LaTeX Math Inline body p_e
:LaTeX Math Inline body --uriencoded--p_%7Bwf%7D
| LaTeX Math Block | ||||
|---|---|---|---|---|
| ||||
q=J \cdot (p_e - p_{wf}) |
and as such depends on how formation pressure is maintained
over time.LaTeX Math Inline body p_e = p_e(t)
The reservoir pressure maintenance is performed by either aquifer or Fluid Injection.
One of the main purpose of injection wells is to maintain pressure in producers and correspondingly maintain production rates.
The ability of injection well to maintain the pressure in producer depend son cross-well connectivity which is a function of reservoir properties extending between the wells.
The ultimate purpose of CRM is to correlate between the long-term (few months or longer) flowrate history and BHP history (recorded by PDG).
The CRM is trained over historical records of production rate, injection rates and bottomhole pressure variation.
The major assumptions in in CRM model are:
- productivity index of producer stays constant in time
- dynamic drainage volume of producer is finite and constant in time (which is equivalent to PSS flow regime)
- total compressibility within the drainage volume of a given producer stays constant in time
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Assumption 2 means that interference between producers is fairly constant in time despite the rate variations and their impact on the dynamic drainage volumes.
Goals | Objectives |
| Identify and prioritise production optimisation opportunities | Generate production and formation pressure forecasts based on the bottom-hole pressure and injection rates |
| Identify and prioritise redevelopment opportunities | Assess productivity index of producing wells |
| Identify and prioritise surveillance candidates | Assess dynamic drainage volume around producing wells |
| Quantify connectivity between injectors and producers | |
| Assess water flood efficiency against expectations and / or between wells or well groups |
Advantages | Limitations |
| Fast-track | It only models injector-producer system |
| Requires minimum input data (BHP and rates only) | Requires eventful history of injection rates variations |
Robust procedure (no manual setups) | Requires productivity index of producers to stay constant |
| Does not involve full-field 3D dynamic modelling and associated assumptions | Requires the drainage volumes of all producers stay the same throughout the modelling period |
| Only applicable for specific subset of PSS fluid flow regimes |
Technology
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The CRM trains linear correlation between variation of production rates against variation of injection rates with account of bottom-hole pressure history records in producers.
See Capacitance-Resistivity Model @model
| Inputs | Outputs |
|---|---|
| Production rate history | Productivity Index for the focus producer |
| Bottom-hole pressure history | Drainage volume by the focus produce producer |
| Injection rate history | Share of injection going towards the focus producer |
| PVT model |
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