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MBAL

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mohamed balaha

on 29 April 2013

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Transcript of MBAL

Defining the PVT Defining the Reservoir Fluid Oil: this option uses oil as the primary fluid in the reservoir, any gas cap properties will be treated as dry gas
Gas (Dry and wet): wet gas is handled under the assumption that all liquids condensation occurs at the separator. The liquid is put back into the gas as an equivalent gas quantity. The pressure drop is therefore calculated on the basis of a single phase gas, unless water is present
Retrograde Condensate: this model takes into account liquid dropout in the reservoir at different pressures and temperatures
General: this allows a tank to be treated as an oil leg with a gas cap containing a condensate rather than dry gas. In other words a tank can be treated as an oil tank with an initial condensate gas cap or as a condensate tank with an initial oil leg. The first step in entering the PVT data in the fluid properties dialogue box
Enter the following:
Formation GOR: is the GOR at bubble point and should not include free gas production
Oil gravity
Gas gravity
Water salinity
Mole percentage H2S
Mole percentage CO2
Mole percentage N2
Appropriate separator: single or two stage
Select the correlation to apply
Uncheck the “use tables” box if the PVT tables have been entered and you dont want to use them instead of the correlation
Uncheck the “use matching” box if the correlation have been matched and you want to use the original unmatched correlation
Check the “Controlled Miscibility” box and enter the gas remixing percentage if you want to control how free gas redissolves into the oil if the pressure of the fluid increases Correlation Where only basic PVT data is available, the program uses traditional black oil correlations, such as Glaso, Beal, and Petrosky etc. Open the PVT dialog box, and enter the following data:
Formation GOR
Oil gravity
Gas Gravity
Water Salinity
Mole percentage H2S
Mole percentage CO2
Mole percentage N2
Then choose the correlation you want MBAL to use to calculate the rest of the data
Click “Done” Matching Where both basic fluid data and some PVT laboratory measurements are available, MBAL modifies the black oil correlation to best-fit the measured data using a non-linear regression technique. This facility can be accessed by clicking the “Match” command in the fluid properties dialogue box.
Up to 50 PVT tables can be entered which are sorted by temperature
The data can be entered manually or imported from an excel sheet Once the data is entered, click on “match” and after the matching box appears click on “calc” to start the calculation.
To view the match coefficients and fluid properties click on “match param” box, if the data obtained after matching is good for you then click on “done” “done” till you reach the fluid properties dialogue box and then check the “use Matching” box, if not then uncheck it. Tables Is when detailed PVT laboratory data is available. MBAL will use the data in the PVT tables in all further calculations only if the “use tables” box is ticket. Up to 50 PVT tables can be entered and each table may use a different temperature, if the program requires data that is not entered in the tables it will calculate it using the selected correlations.
To access the PVT tables click on the “Table” icon, and enter the data either manually or import it from an excel sheet.
To access the next PVT table click on the arrow next to the word Table 1. After entering the data click on “done” and go back to the fluid properties dialogue box and check “use tables”, after you are done click on “done” to exit the fluid properties dialogue box. General In the system options first choose in the reservoir fluid field “General” 1 2 Then open the pvt fluid properties window, you will find three tabs: Oil, Condensate, and Water
In the oil tab enter the same data you used to enter before, and the same options of tables and matching and controlled miscibility exist. 3 In the condensate tab you will have to enter:
Separator pressure
Separator temperature
Separator GOR
Separator gas gravity
Tank GOR
Tank gas gravity
Condensate gravity
Dewpoint at reservoir temperature
Reservoir temperature
Reservoir pressure
Mole percentage H2S
Mole percentage CO2
Mole percentage N2
Here we also have the same options to use matching or from tables directly exactly like mentioned before in oil 4 If we choose tables we will have to enter the data in the table or import it and we can also add more than one table with the variable being the temperature and the dew point 5 In the water tab you will have to enter just water salinity And we can also use tables to input the data or import it 6 Checking the PVT Calculation To check the PVT data entered choose calculator from the PVT menu
Enter the range of temperatures and pressures you want to view the data of and the steps you want in between the intervals
After that click on calc again to show the results, and to view a plot of the results click on plot, and to change the variables that are plotted click on variables. Oil Decline Curve Analysis Defining the Fluid From the tools select decline curve
Open options to define the reservoir fluid and production history method:
By tank: this requires to enter the history of a single well or the reservoir as a whole
By well: this is a well by well option that requires to enter the production history for each well or group of wells Entering the Production History Click on the "Input" button then enter the following:
Well name
Choose the decline type:hyperbolic, harmonic or exponential
Production start date
Abandonment rate (optional):the minimum production rate for the well
Decline periods
Production history
After that click on match and then regress to match the decline curve. Setting up the prediction Open prediction setup
Enter prediction start and end dates along with the abandonment rate Setting Reporting Schedule Set the production schedule to automatic, this option tells the program to display a calculation every 90 days.
press done to run the prediction Running the prediction Click on "calc" to start the prediction
You can also plot the results by using the plot tool Production data can be fitted to Hyperbolic, Exponential pr Harmonic declines. These can be then extrapolated into the future generation of forecasts. This tool analyses the decline of production of a well or reservoir versus time. It can be used for production history matching and/or production prediction. Monte Carlo Simulation This tool enables the user to perform statistical evaluations of reserves. Distributions can be assigned to variables like porosity or thickness of the reservoir and the program will generate the range of probabilities associated with a reserves range. This technique is used to evaluate the hydrocarbons in place. Defining the Primary Fluid of the Reservoir From the tools select monte carlo
Go to options
Next step is supposed to be defining the PVT but this has already been explained before in this lecture. Entering Reservoir Parameters From input chose "distribution"
Input the following:
Number of cases: the number of segments of equal probability that the distribution will be divided into
Histogram steps: the number of steps that will be plotted on the histogram
Temperature
Reservoir initial pressure
Chose the method to be used in calculating the pore volume
Select the appropriate distribution type for each reservoir parameter, and enter the values required. Starting the Calculation Click on "Calculate" under calculation
Then press on "calc" Viewing 90,50,10 P's In the calculation window click on "Results"
To view the calculations graphically on a histogram click on "plot" 1 D Model Introduction This model uses the classic buckley leveret tool of predicting breakthrough times and saturations in a water flooding scenario
This model assumes:
A rectangular reservoir with a injector well at one end and a producer on the other end
Both the producer and injector well are perforated across the entire formation thickness
The injection rate is constant
The fluids are immiscible
The displacement is considered as incompressible
The saturation distribution is uniform across the width of the reservoir
Linear flow lines are assumed, even in the vicinity of the well
Capillary pressures are neglected
The reservoir is divided into cells, a time step is computed according to the injection rate and the size of the reservoir, at each time step and each cell MBAL claulates:
Water gas and oil relative K’s based on cell’s saturations
Fractional flow of each fluid based on their relative k’s
Cell production into the next cell based on fractional flow’s
New cells saturation based on the production Defining the Primary Fluid Open system options to define the primary fluid in the reservoir, in this tool only oil is available Inputting Reservoir Injection & Fluid Properties Open input reservoir parameters to input reservoir injection and fluid properties, Input:Injection fluid: water or gas
Injection rate: in STB/day
Start of injection
Oil density
Oil viscosity
Oil FVF
Solution GOR: used in gas injection only
Water/gas density
Water/gas viscosity
Water/gas FVF
Reservoir length
Reservoir width
Reservoir height
Oil/water contact or gas/oil contact
Dip angle
Permeability
Porosity
Connate water
Cut-off water cut or GOR: value at which MBAL will end the simulation
Number of cells: maximum 500 Inputting Relative Permeability’s Corey Functions Tables Open input relative permeability’s to access the relative permeability’s
Choose from where to get the relative permeability’s: corey functions or user defined input tables
After defining by using any of the methods, you can plot the relative permeability curve to check the quality of the data If you choose corey functions, enter the following:
Residual saturations: the connate saturation of the water phase and the residual saturation of the oil phase for water flooding.
End points: is the relative k’s at its maximum saturation for each phase.
Corey exponent: defines the shape of relative permeability curve between the residual saturation and maximum saturation for each phase. If you choose from tables:
Enter both data for Sw and Krw along with So and Kro Running Simulation Now we can run a simulation, by clicking on calculations and then run simulation, then press calculate again. A graph like this will show. For a complete output click on output results. Plotting Calculated Variables To plot the output variables against each other we can use the plot button, then click on variables to choose between any two variables. Multi Layer Relative Permeability’s averaging for different layers can be done using this tool. The purpose of this tool is to generate pseudo relative permeability curves for multi-layer reservoir using immiscible displacement. These can then be used by other tools in MBAL such as Material Balance. Specifying Reservoir and Injected Fluid Choose from tools the multilayer tool and then click on options to define the following:
Initial reservoir fluid type
Injected fluid
Calculation method: buckley-leverett, stiles, communication, simple
After that the PVT description is entered as shown before Reservoir Description To specify the reservoir parameters click input reservoir parameters and enter the following:
Reservoir initial pressure
Reservoir temperature
Reservoir dip angle
Cut-off water cut or GOR: value at which MBAL will end the simulation
Injection rate
Reservoir width Layer Description Basic Layer Description Choose input layer properties to enter the layer properties, enter each layers:
Thickness
Porosity
Permeability
Water break saturation Defining each layers Relative Permeability Curve Click on rel perm to enter the Relative permeability curve
Choose from where to get the relative permeability’s: corey functions or user defined input tables
After defining by using any of the methods, you can plot the relative permeability curve to check the quality of the data. Corey Functions If you choose corey functions, enter the following:
Residual saturations: the connate saturation of the water phase and the residual saturation of the oil phase for water flooding.
End points: is the relative k’s at its maximum saturation for each phase.
Corey exponent: defines the shape of relative permeability curve between the residual saturation and maximum saturation for each phase. Tables If you choose from tables:
Enter both data for Sw and Krw along with So and Kro Running Simulation Now we can run a simulation, by clicking on calculations and then run simulation, for a complete output click on output results, and these variables can be plotted against each other using the plot button. Reservoir Allocation Introduction When a well is producing from multiple layers, it is essential for an engineer to know how much each layer has contributed to the total production. MBAL improves allocation by allowing the user to enter IPR data for each layer and calculates the allocation by taking the rate of depletion into account as well. Crossflow is also accounted for in the model, as well as different start/finish times for each well. Impurities are also tracked and can provide as effective measure of the quality of the underlying assumptions in the case where few data is available. Defining the Reservoir Fluid Choose from tools the reservoir allocation toolClick on options to enter the reservoir fluid type And enter if there is impurities that need to be tracked in the model for comparison with measured percentages at the end of the allocationAfter that enter the PVT data as shown befire Defining Tank Data Tank Parameters Click on input and then tank data and enter:
Tank temperature
Initial pressure
Porosity
Connate water saturation
Water compressibility
Initial gas cap
OOIP
Start of production
You can add as many tanks as you wish by clicking on the plus sign Relative Permeability Corey Functions If you choose corey functions, enter the following:
Residual saturations: the connate saturation of the water phase and the residual saturation of the oil phase for water flooding.
End points: is the relative k’s at its maximum saturation for each phase.
Corey exponent: defines the shape of relative permeability curve between the residual saturation and maximum saturation for each phase. Tables If you choose from tables:
Enter both data for Sw and Krw along with So and Kro Click on rel perm to enter the Relative permeability curve
Choose from where to get the relative permeability’s: corey functions or user defined input tables
After that you can plot the graphs of the relative permeability's to check the quality and validity of the data. Defining Well Data Setup Choose the well type and if you want to add wells you can add by clicking on the plus sign Choose input well data to define the wells. Production History Now enter the production history by clicking on the production history tab, this can be imported from an excel sheet or entered manually Inflow Performance Now enter the inflow performance of the well
Enter the productivity index of the well Calculation Setting up allocation size Click on calculation and then setup
Set the allocation setup size to automatic Start Calculation Click on calculate and then run allocate and click on calculate to start calculating
We can use the tank result option to display the tank and results from a production allocation Comparing between Wells and layers If we want to compare between wells and layers we can use the well/layer results option to plot and compare graphs of each layer and each well Material Balance Introduction This tool incorporates the classic use of material Balance calculations for history matching through graphical methods. Detailed PVT models can be constructed for oils, gases and condensates. Furthermore, Prediction can be made with or without well models and using relative permeabilities to predict the amount of associated phase production.
Throughout the reservoir the following assumptions apply:
•Homogenous pore volume, gas cap and aquifer
•Constant temperature
•Uniform pressure distribution
•Uniform hydrocarbon saturation distribution
•Gas injection in gas cap Defining the System Choose from tools the material balance tool
Click on options to access system options box to enter the reservoir fluid type
Enter Reservoir fluid type: oil, gas, ret condensate, general
Now define the PVT as shown previously Defining the Tank Data Tank parameters Click on input tank data, choose tank parameters then enter the following:
•Tank type: oil, water
•Temperature
•Initial pressure
•Porosity
•Connate water saturation
•Water compressibility(optional): this can be entered or left empty and MBAL will extrapolate it from the PVT tables or will use an internal correlation to evaluate it
•Initial gas cap
•Initial oil in place
•Start of production date Water Influx Choose water influx
Select an aquifer model from the following:
Small pot
Schilthuis steady state
Husrt steady state
Husrt-van everdingen odeh
Hurst-van everdingen dake
Vogt wang
Fetkovich semi steady state
Fetkovich steady state
Husrt-van everdingen modified
Carter tracy
Enter the following:
Aquifer system: radial aquifer, linear aquifer, bottom drive aquifer
Reservoir thickness
Reservoir radius
Outer/iner radius ratio
Encroachment angle Rock Compressibility Choose Rock Compress.
Choose from the following:
From Correlation: MBAL will use an internal correlation to evaluate the compressibility as a function of the porosity
Variable vs Pressure: you can enter rock compressibility values that vary with pressure, compressibility can be defined on original volume or on tangent
User defined: the formation compressibility must be entered and MBAL will assume that the compressibility does not change with pressure
None: if there is no rock compressibility Rock Compaction Choose rock compaction
Check the Enable Model box
Check the Reversible box: if this option is not checked the pore volume will not increase back to the original volume if the reservoir re-pressurises
Enter in the table the Tank pressure and the Compaction factor corresponding to it Relative Permeability Tables If you choose from tables:
Enter both data for Sw and Krw along with So and Kro and Sg and Krg Corey Functions If you choose corey functions, enter the following:
Residual saturations: the connate saturation of the water phase and the residual saturation of the oil phase for water flooding.
End points: is the relative k’s at its maximum saturation for each phase.
Corey exponent: defines the shape of relative permeability curve between the residual saturation and maximum saturation for each phase. Click on rel perm to enter the Relative permeability curve
Choose from where to get the relative permeability’s: corey functions or user defined input tables
After that you can plot the graphs of the relative permeability's to check the quality and validity of the data. Entering Tank Production History Choose production history
Then enter the following data:
Date
Reservoir pressure
Cumulative oil production
Cumulative gas production
Cumulative water production
Cumulative gas injected
Cumulative water injected
These data can be imported from an excel sheet History Matching Viewing History Matching Plots Click on history matching and then all to view the history matching plots Activating the Regression Analysis In the history matching plots click on the analytical method plot, then click on regression to match the model with the measured data in the analytical method plot.
Select the parameters with the least trusted or the ones for which values were assumed rather than measured, then click on calc to start the regression.
The values are observed on the right hand side, if they are satisfying, then the values can be used in the model by clicking on the arrow beside Best fit.
After that the history match plots are re plotted to see if the plots are satisfactory or not. Checking the History Match using Simulation Click on history matching, then choose run simulation and then click on “calc” to start the simulation.
After the simulation is calculated, click on plot to view the pressure vs time plotted for both simulation and history data, if both curves are overlapping, then this is a good history match. Matching Relative Permeabilities Fractional flow curves are created to match relative permeabilities.
Click on History matching then choose Fw matching
After the fractional flow curves are plotted, the regression tool is chosen to regress the available historical data in order to fit the fractional flow curve, this will create a set of rel perm curves that will be used to predict the fractional flow of water. Prediction Prediction With No Wells Prediction Setup Click on production Prediction and then prediction setup
Choose Predict Profile from Production Schedule (No Wells)
And tick Use Relative Permeabilities Production Constrains Click on Production prediction then choose production and constrains
The oil production desired is entered in the constrains along with the start date
This production will be kept constant throughout the prediction, until the reservoir does not have enough energy to support it. Reporting Schedule Click on Production Prediction and then choose reporting schedule, then choose one of the following settings:
Automatic: MBAL displays a calculation every 90 days
User List: a list of dates can be set in the table
User Defined: any date increment in days, weeks, months or years can be defined
Click on Done Running Prediction Click on production prediction, then run prediction, in the window that appears click on calc to start the calculation. Plotting the Prediction In the production prediction window click on plot and then choose variables to choose what variebles you want to plot vs each other. Prediction Using a Well Prediction Setup Go to the prediction setup window by clicking on production prediction and then production setup
Choose from the drop down menu “production profile using well models”
Then click done Entering the Constrains Click on production prediction then click production and constrains
The well head pressure now needs to be specified in the constrains
Now click on done Defining the Well Click on Production prediction and choose well type definition
Add a well by clicking on the plus sign next to well
Choose from the drop down menu the well type and then click on next Setup Add a well by clicking on the plus sign next to well
Choose from the drop down menu the well type and then click on next Defining Inflow Performance After clicking next now you can choose to enter the inflow performance data using IPR by clicking on match IPR
Then enter the liquid rate and the FBHP corresponding to it along with the reservoir pressure and watercut, then click on calc Defining Abandonment Constrains Click on More inflow and enter the constrains you want if necessary Defining the Outflow Performance In the well input data window click on outflow performance
And enter the outflow performance data which is the liquid rate and the FBHP for every well head pressure, water cut, and GOR.
Then click done and done Setting well Schedule Click on production prediction then well schedule
Enter the well opening or closing time, the number of wells and the well name Reporting Schedule Click on Production Prediction and then choose reporting schedule, then choose one of the following settings:
Automatic: MBAL displays a calculation every 90 days
User List: a list of dates can be set in the table
User Defined: any date increment in days, weeks, months or years can be defined
Click on Done Running Prediction Click on production prediction, then run prediction, in the window that appears click on calc to start the calculation. Plotting the Prediction In the production prediction window click on plot and then choose variables to choose what variebles you want to plot vs each other. Predicting the Number of Well Needed to Achieve Target Rate Running Prediction Click on production prediction, then run prediction, in the window that appears click on calc to start the calculation.
As shown below the number of wells is shown Plotting the Prediction In the production prediction window click on plot and then choose variables to choose what variebles you want to plot vs each other. Setting the Prediction Click on production prediction and then choose prediction setup
Choose from the drop down menu “calculate number of wells to achieve target rate”
Choose the target type
Then click done Entering the Constrains This option need a defined well type to add as many wells of this type as needed to achieve the specified target
Click on production prediction and then choose production constrains
specifying the target rates and the well head pressure along with the starting date
click done Potential Well Schedule In this section we specify how many wells are allowed to be drilled and the minimum drill time needed to drill that well and the type of each well
Click on production prediction and choose potential well schedule, then enter the mentioned data and then click done Matching of Water Cuts In order to quantify exactly how much difference there is in terms of actual water cut in the history and the match of the model. To do that a prediction of history is done where the production history of oil is fixed and the production of water and gas will be calculated based on the fractional flow curves and then compared to the historical production. Setting up the Prediction Click on production Prediction and then prediction setup
Choose Predict Profile from Production Schedule (No Wells)
And tick Use Relative Permeabilities
Set the prediction start to start of production
Set the prediction finish to end of production history Historical production Volumes The historical production volumes of oil have to be extracted from the tank
Click on production prediction then choose production constrains then click on copy to copy the historical rates Reporting Schedule Click on Production Prediction and then choose reporting schedule, then choose one of the following settings:
Automatic: MBAL displays a calculation every 90 days
User List: a list of dates can be set in the table
User Defined: any date increment in days, weeks, months or years can be defined
Click on Done Running Prediction Click on production prediction, then run prediction, in the window that appears click on calc to start the calculation. Plotting the Prediction In the production prediction window click on plot and then choose variables to choose what variables you want to plot vs each other. Select both history and prediction steams to be plotted together, to see if there is a good agreement between the data and the forecast or not, if yes then the model is ready for prediction Introduction MBAL is a package made up of various tools designed to help engineers gain a better understanding of reservoir behavior and perform predictions. The various tools available in MBAL are:
Material balance
Reservoir Allocation
Monte Carlo Volumetric
Decline Curve Analysis
1-D Model (Buckley-Leverett)
Multi-Layer (relative permeability averaging)
This presentation explains the basic procedures to follow in order to set-up an MBAL Oil model. This presentation focuses on how to use the various program features as analytical tools to solve engineering problems. Unfortunately this presentation only focuses on Oil reservoirs, gas and condensate reservoirs are not explained in this guide. This Presentation is done by:
Mohamed Ibrahim Balaha
Under the supervision of:
Dr Atia M Atia
Full transcript