History Matching in Eclipse

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History Matching in Eclipse

Post by FANARCO »

Traditional History Matching


History Matching and Predictions



Simulation of hydrocarbon reservoir performance can be divided into two phases namely:-


•History Matching: Comprising the adjustment of reservoir parameters in the model until the simulated performance matches the measured information.
•Future Performance Prediction: Refers to the simulation of future reservoir performance
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Re: History Matching in Eclipse

Post by FANARCO »

• Normally the most time-consuming phase of a simulation study.
• Used to demonstrate the validity of the simulation model.
• Input historical production rates of oil/gas and well pressures then simulator calculates pressures and secondary products (GOR, WC, etc.) to be compared with history.
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Re: History Matching in Eclipse

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Mathematically: Inverse Problem

That is, we know the Model and we know the answer, but we do not know the input to the model.

There are special techniques for solving inverse problem, but these do not apply to reservoir simulation history matching.

Thus, we use trial and ERROR.
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Re: History Matching in Eclipse

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• Special Case of Inverse Problem

• Our Geologist, Geophysicist, Petrophysicist, Well Test Engineer give us an estimate of the input parameters (k, kr, Φ, layering, structure, faults, etc.) with an uncertainty level, that is a ± b.

• Note sometimes level of uncertainty is not expressly given
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Re: History Matching in Eclipse

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History Matching with Uncertainty
Exercise Simplified




• Given inverse problem with uncertain input data

• Your job: Match the history (within its uncertainty)

• Run the prediction

• Each group will report their history match parameters and the prediction value
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Re: History Matching in Eclipse

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Variables that can be considered for a history match study



• Porosity (local)
• Water Saturation (Global)
• Permeability (Local)
• Gross Thickness (Local)
• Net Thickness (Local)
• kv/kh Ratio (Global .. Local?)
• Transmissibility (x/y/z/) (Local)
• Aquifer Connectivity and Size (Regional)
• Pore Volume (Local)
• Fluid Properties (Global)
• Rock Compressibility (Global)
• Relative Permeability (Global
- regional with Justification)
• Capillary Pressure (Global - regional with justification)
• Mobile Oil Volume (Global..Local?)
• Datum Pressure (Global)
• Original Fluid Contact (Global)
• Well Inflow Parameters (Local)
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Re: History Matching in Eclipse

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The following variables are often considered to be indeterminate (high uncertainty):


- Pore volume
- Permeability
- Transmissibility
- Kv/Kh ratio
- Rel. perm. curves
- Aquifer properties
- Mobile oil volumes
- Well inflow parameters
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Re: History Matching in Eclipse

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The following variables are often considered to be determinate (low uncertainty):


- Porosity
- Gross thickness
- Net thickness
- Structure (reservoir top/bottom/extent)
- Fluid properties
- Rock compressibility
- Capillary pressure
- Datum pressure
- Original fluid contact
- Production rates History
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Re: History Matching in Eclipse

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History matching

– Helps to identify the weaknesses in the available data,

– Improves the reservoir description and forms basis for the future performance predictions.
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Re: History Matching in Eclipse

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The processes which we can control during history-matching are:


- The initial quantity and distribution of the fluids within the system
- The movement of fluids within the system under pressure gradients
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Re: History Matching in Eclipse

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• Data uncertainties

– Oil production rates are usually measured systematically and accurately but Water Oil Ratio and Gas Oil Ratio measurements are done occasionally.

– Rate fluctuations are usually smoothed out as they can occur at very short intervals.

– Gas rates are not measured accurately especially when part of it is being flared.
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Re: History Matching in Eclipse

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Data uncertainties

– Injection data can be less accurate than production data due to measurement errors, fluid losses into other intervals due to leaks in the casing or flow behind the pipe.

– Well test data are usually reliable when build up records are taken.

– Pressures measured during flow tests are usually less reliable than those obtained during shut in.
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Re: History Matching in Eclipse

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• Reservoir formation parameters are usually measured at the point of observation - wells.

– These are porosity, permeability, relative permeability, capillary pressure etc.

– Inferred parameters between wells are usually associated with high degree of uncertainty.
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Re: History Matching in Eclipse

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• Having set of parameters that match the reservoir performance available does not guarantee accurate future performance predictions.

• The duty of reservoir management is to direct efforts in simulation studies to quantify uncertainty in the future performance predictions.
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Re: History Matching in Eclipse

Post by FANARCO »

History matching is normally carried out in these stages:


- Define which data is determinate and which is indeterminate
- Define the data to be compared and the tolerances
- Determine the solution technique
- Match the pressures (field or reservoir pressure)
- Match the GOR/water-cut, etc.
- Match the FBHP History
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