Translate from original TEMR contribution By AYAX

Chapter 1Introduction to geological modeling and reserve calculation

The science of geological modeling and reserve calculation was born when the human started to ask the how I can calculate what I have in place, the more sophisticated publication were started to appeared at the beginning of 20 century. I will simplify and give just background if you need detail you can find books in this folder for almost any discipline I will mentionSo what data are used calculate what is in place???

1. Interpretation of seismic 2D lines or 3D survey.

The approach of for seismic interpretation is the following: The waves in medium are traveling with certain speed, the more density of medium the faster wave passing the medium. On the boarder of 2 medium with different densities speed of wave is changing - this is key principal in seismic acquisition and interpretation process.To get or write seismic, on surface you need source of wave (vibrator or dynamite) and receiver. You produce waves and read what time each produced wave travel to ground reflects and been read by receiver. Then you start to process seismic. The final result is seismic in time. To convert you seismic to depth you need to build valid velocity model based on measurements in wells.

“So results of seismic can give you boundary of two media with different density - this may be horizon or fault.”

The other thing you can do with 3D seismic is to define different geo-bodies and attributes; based on them you can predict some parameters in inner well space like pseudo-porosity.

2. Well Data

The data you use is horizons boundaries and log interpretation. During well drilling, well logging process taking place, the purpose of this process to make measurements in drilling hole to do the following:

Define litology Define porosity Define resistivity

Several logging tools are available now, but all of them are working based on physical effects and the sources of them measurements are

1. Radioactivity2. Wave time travel3. Resistivity

The boundary of horizons

I will pass interpretation of the horizon process as this is process where person interpret horizon boundaries based only on his experience and vision and if, for example you put 2 geologists in to 1 data set you will get at the end two different results - it is not a joke.

Log interpretation The logging tools writes data vs. depth on step basis - it mean there is no data between steps, and as usual this data are results of linear interpolation of two points. The standard for now is Las 2.0 So interpreter uses several set of curves and his task is to calculate following set of curves

1. Pay2. Porosity3. Sw 4. Ressum table

So this 3 set of curves are a must to calculate reserves in model

“Reservoir summation table is table where you put averages values for each well for each horizon”.

3. Core data

During drilling also you need to take the core sample, and for running following analysis 1. RCA 2. SCAL

RCA (Routine Core Analysis)On this analysis you get following data:

1. Porosity measurements (to match calculated vs. fact porosity)2. Density measurements (to get constants when calculating porosity from density logs)3. Permeability vertical horizontal (needed for permeability calculation and cut off)4. Core structure analysis (for litology purposes)5. Litology analysis (for facies model purposes)6. Resistivity analysis (core sample saturated with brine to get resistivity values for Sw calculation by Archie formula)

SCAL (Special Core AnaLysis):

1. Capillary pressure (defining the values of pressure and irreducible water saturation Swi)2. Defining residual oil saturation (Imbibition drainage process)3. Relative permeability (Imbibition drainage process)Relative permeability directly not isn’t used in geological modeling but can be helpful during defining Sw cutoff

Well test data To define position of you oil-water contact or gas-oil contact or gas-water contact you need to data 1. Sw by logs2. Well test data

Well test dataAfter well finished you need to perforate and test it so each well has this following data during testing1. Date of testing 2. Interval of testing

3. What been produced from intervalYou will need all this data when you will define you initial OWC (Oil-Water Contact). Some times OWC tend to go up during production and for this you need to analysis dates and if need trash the certain data as

YOU CAN CALCULATE RESERVES AT TIME WHEN NO PRODUCTION TOOK PLACE

Fluid dataTo get this data samples of fluids for reservoir take to laboratory, where several tests run the result of this several test, but you need following

1. Initial Formation Volume Factor of oil (Bo - says what fraction of oil in reservoir condition to standard conditions)2. Initial Formation Volume Factor of gas (Bg - says what fraction of oil in reservoir condition to standard conditions)3. Initial Gas Oil Ratio (GOR - says how much gas solved in 1 volume of oil in reservoir conditions)4. Initial condensate (Rv - says how much condensate solved in gas)

Reserve calculation formulae

So how do we calculate reserves in place in standard conditions?Before we need to calculate HSPV - hydrocarbon saturated pore volume Bulk=All volume of you reservoir which lays above owc NTG = Ration of net thickness to gross thickness in wellsNET=NTG*BulkPORO = average (weighted on net) porosity values PV=Poro*NetSw= average (weighted on PV) Sw values Soil=1-SwSgas=1-Sw-SorWhere Sor oil residual oil saturationHSPV= Bulk*NTG*Poro*(1-Sw)For gasHSPV= Bulk*NTG*Poro*(1-Sw-Sor)

Oil in standard m3OIP= HSPV*(1/Bo)Gas free in standard m3GIP= HSPV*(1/Bg)Gas solved in standard m3GIP= OIP*GORCondensateCondensate= GIP *Rv

One lyric step out During my long practice i heard a lot of time that old fashion reserve calculation or manual and modern 3D systems are different in they approach(1) . My opinion is that they implement same algorithms and the different between them is that 3D models give more precise results than hand calculation, keep this in mind when you will work with old people who far from 3d models, and try not to harm them with the expression(1) which is not correct

Overview of the Petrel - general what you can done and what you cannot done with petrel

So for newcomers there is a hard decision what software to use. To this moment on the market, there are several commercial packages available.

They are:

There is also in-house software like Gocad but in order to work on them you need to work in Host Company. The most popular are Petrel form Schlumberger and Rms from Roxar. It is up to you what to choose but I would advise you take Petrel and to understand the reason lets go to the past...................

In 2002 Schlumberger acquired Technoguide Company and there product Petrel. But who are this people standing for Technoguide Company? Several Roxar employees for years were trying to enhance RMS with features they thought would break through the product, but as usual management pay no attention to their efforts, and our heroes decided to quite. After they found Technoguide Company and make they own package called Petrel. In 2 years they throw away RMS from key customer- that was their 1st win and sweet revenge....

So Petrel is enhanced and more advance version of RMS - take the best.

So for what purposes you can use petrel:

1. Data base - it is quite reliable data base which can contain various type of data related to you project. The data of a various types, even you can store reservoir maps in jpeg format, how - will be shown later.2. Log interpretation tool - within petrel you can make simple calculations on well logs, make statistics and make regression analysis calculations. Petrel does not have building petro physical formulas but you can easily put them the only requirements for that you need to know them.3. Geological interpretation tool - you can easily build cross-sections with certain logs to make geological interpretation of your horizons. It is more users friendly and easy to understand process 4. Fluid contact interpretation - making comment logs you can easily make cross section with all you well tests to see the depth of you well inflow5. Making function - you can make correlation of 2 parameters and create function. This function can be used as trend or input data. This tool is quite useful as it allows you fast to find needed correlation. For example you need to see is there any function between depth and poro. In normal life you would need to open each log and put values of depth curve and poro curve to excel sheet. Here you just click 2 buttons and you get your correlation. 6. Making editing surfaces - You can make and edit surfaces using several algos, and make any statistic , volume and area calculation and different edit operations.7. Loading and visualizing 2D and 2D seismic - Loading 2D 3D seismic8. Interpret seismic (horizons, bodies) - several tools available for seismic interpretation, but as I said before I will pass this section as I am not professional in it 9. Building velocity models - making simple velocity models to convert from time to depth

SchlumbergerPETREL

RMSROXAR

POWERMODELLANDMARK

10. Making fault models - Advance tool to create fault with vast import parameters, will be covered later.11. Making corner point grid - The corner point format assumes that grid cell corners are distributed along vertical, linear pillars. All grid cells have 8 corners, but these may not be geometrically distinct due to grid pinch-outs. Since the grids are allowed to contain vertical faults, all the eight corners are provided for each grid block.12. Structural modeling - Making complex horizon and zones with possible pitchout zones 13 Facies modeling - facies are a body of rock with specified characteristics, so petrel has as deterministic and stochastic algos to model. Also it has algos to model environment of depositions like channels, delt, etc.14 Petro physical modeling - quite advance tool to model petro physical parameters like NTG, Poro and Perm in inner well space, I will describe later available algos 15 Volume calculation - Calculate volumes of you model for any type of HC 16 Make up scaling - Up scaling process is when you try to change resolution of you new grid but take parameters from existing grid with different scale.17 Make data analysis - statistical tools for searching ranges and making proper data destitution will be covered in detail in certain chapter18 Make statistics - this is lack in RMS but vast in petrel you can take any statistic you want 16 Simulation (I will not describe it as running all simulation in other simulator)17. Importing and visualizing eclipse results - this is a keen point as Flowvis is peace of sh*t and completely stacks with big simulation models (>400 k active cells). You can easily import and view you results and print for example current pressure maps weighed on poro volume and get average reservoir pressure around your wells ( more advance compare to WBP9)18. Making workflows - this is powerful tool that can speed up you process it several times; you can create export change rebuild surfaces points logs properties automatically. I will dedicate one full chapter were we will construct several easy workflow and will supply you with existing workflows.19. Writing you own plug-in - but this world is not perfect certain things you cannot do in workflows or you can but the process is to slow. Plug-in is add in you can write in Ocean environment using Visual Basic. It is advance area so if any has Ocean for 2009 you are welcome to post it here.

There is now dedicated workflow to model saturation and this you need to create by yourself

Chapter 2The PETREL environment

In this chapter I will review the interface of petrel with the several comments on how to make certain thing. The way I will structure the manual is the following I will only give you guidelines and hints, everything else you need to do by yourself using petrel manual. Also I will give same web links or links to

materials for advance reading.Before start, download data set from http://www.4shared.com/file/XFoOAaKe/Gmodel.htmlI would recommend in parallel to start also reading books on VBA Excel - it is powerful tool which can help you short you work time consumption several times.For example now for me to load Ressum table as discreet logs to petrel using my macros takes approximately 5 minutes for 100 wells, while manual load of data for each well can take much more timeDuring the course I will supply simple excel spreadsheets with macros which will help you to prepare data for loading, but if you want to understand them and go advanced you need to learn.

The VBA samples link ( Russian English)http://www.4shared.com/file/Gg7CCkcI/VBA_SAMPLES.html The VBA book link (English)http://www.4shared.com/document/XViO...arel_Piet.htmlThe VBA book link (Russian)http://www.4shared.com/document/sWto...Excel2007.htmlAlso I will recommend to following sourcesCoordinates systems -will give you general understanding of projection http://www.colorado.edu/geography/gc...oordsys_f.htmlGeostatic software library till 2008 all Petrel petrophysical algos are describe here)Source code of kriging and SGShttp://www.statios.com/Quick/gslib.htmlAll other handout will come as books and will be putted to the following folder http://www.4shared.com/dir/jEVYIhb4/Books.html

 So let review petrel interface Below is a standard petrel window 

 Below you will find description of each panel

1. Program menu, it content standard menu factions and specific petrel function. Standard you can find in petrel manual for specific useful functions are:

Reference project tool

Reference project tool , this tool is for copy from one project to another with following restrictions, -you cannot copy from newer version background project( let say 2009 version) to older master project let (say 2008 version)-you cannot copy data within different coordinates system, the only data you can copy in this case is a workflow Project settings

 Free memory.

When you work with big models there is problem with allocation of memory and as a result Petrel halted. To avoid this try to use this button- its free reserved program memory.

2. The most useful form my point is

Coordinate system - this one you need to link your well coordinate systems and for example seismic coordinates, also this stuff is required when you work with Google petrel plugging, which will be covered in plug-in section.

3. Custom tool bar dedicated to each process we will cover it in other chapters

4.In the window you can display following data3D window - all 3d data 2D window - all 2D dataFunction window - function you build in petrelHistogram window - statisticsMap window - maps Well section window Cross section window - cross section of 3d property to add new window

Keep in mind that having many windows in project can result to slow Petrel work - try to minimize number of you windows  

5. The actual data base of all input data you loading in project which is: 1. Well data - well head, deviation, logs, core data, pictures, comment data, event data, production data2. Seismic data - 2D, 3D seismic and interpretation, note that Petrel do not store the Seismic as own binary, unless you make attributes, its seismic link file to project. So if you copy project do not forget to copy seismic data 3. Surface or points - grid surfaces or points data, usually seismic interpretation of created surfaces 4. Tops data - geological interpretation of your horizons or faults there are other type of data but we will focus on this 4, because this is the minimum set to able you make valid model and reserve calculation.

6. The corner point property grid repository. Place where petrel stores all 3D Models

7. - The results window.

8. The place where petrel stores all data templates .Here by 2 clicking you can change template of any existing or add your templates.

9. The workflow repository. This is the place where petrel stores the user’s workflows. This is advance part of Petrel, and as far as I know none of the existing programs has the same

variety and flexibility of user commands or macros like petrel does. So if you want to be faster than people around pay a lot of attention to the chapter where we will cover basic macro programs.

10. The processes menu. If you want to know what petrel can do in terms of task just open the menu and what is there

1. Importing data to list all available formats petrel can talk to just click for 2009 it is 125 but be very open to ASCII format 2. Stratigraphic modeling - make edit tops and well correlation3. Geophysics - seismic interpretation and attribute analysis, velocity modeling4.Structural modeling - fault modeling, making grid 5.Property modeling - or modeling properties in inner well space6.Upscaling - process where you change transform property values from one geometrical scale to another 7.Fracture modeling - tool to model fractures, as its related to double poro or perm models I will not describe it as it is advance tool.8. Well engineering - tool to model well construction, but where and how to put project wells it will not say you, this is something I will explain you in separate chapter 9. Simulation - having license of eclipse you can run simulation case by Petrel - I will pass this cause I running simulation in Tnavigator, the tool is more advance in terms of interface than eclipse but giving the same results, so if you will have question ask but there will be no dedicated chapter for this process10 Utilities - All utilities you need to run you gmodel, will be covered in detail later11. Plug-ins - user programs if I will find plug-ins for 2009 I will make brief overview of them. In order to create them you need to have Ocean API license and be advance in with Visual Basic 

11. The place where all you result cases are stored like volume calculation

12. Windows management window. you can switch here between your windows add or delete the one you do not need

Chapter 4Well heads

Chapter 4 part 1.In this chapter we will load well data needed for the project which are 1.well heads data 2.well logs data 3.event data 4.production data5.comment log data6. Tops dataWell heads Start petrel an safe you project

Now you have plain project.The first thing you need to do is load you well heads data. The following data are a must: 1. Well

name 2. X-

coordinate3. Y-coordinate4. Kelli bushing 5. Bottom depth6. Well Deviation.For this project I skip deviation but will give you short description.All data mentioned above are well known. I want to keep you attention on kelly bushing kelly bushing or rotary bushing is an adapter that serves to connect the rotary table to the kelly.But in petrel this is altitude or subsea true vertical depth (SSTVD) of rotary table. Why rotary table not well head?? The main reason is that you make logging form rotary table and measure depth (MD) from the table. Kb and well deviation then used to convert your MD values to SSTVD values.I supply the file with small macro for you is the main task to analysis it as I will use this file in my next examples Note. In order to make the button working you need to enable macros in you excel do the following

http://www.dds.ca.gov/WorkServices/d...structions.pdfin the excel file you have all data needed so press the button

After pressing the button the will be file in the directory where you place excel file. This is text file with all the data needed to load your well heads Return to your input window in Petrel.

Right click and choose import to the tree You will be taken to petrel import window

if you open file type window you will see the list of formats that supported by petrel Note: there two major types of format ASCII and binary try to use ASCII format when taking or giving data as you can read data in this format.

From drop down menu choose well heads

And choose our file heads.inc

Petrel read the file and show dialog:

As I used headers I old petrel the data I use in text file. But if you are not use headers you can do manual assign of columns in the file

Press cancels and does the following

Open in test editor file heads.inc

Delete 3 first rows save and close the file

Now repeat opening of well heads

This is standard window if you are not using headers or your headers corrupted

So now let’s make manual load Press left button of your mouse and select all columns and press remove button. Now click 5 time on add

button, you will get following window.

Now you get well folder with your wells Click and launch new 3D window here

Select all wells by pressing to wells.

To change appearance of you wells double click on well folder and you will be taken to well global settings window

In Style window you can change appearance of wells. Now let’s go to the menu we have under well folder.There 5 subfolders under wells 1. Global well logs2. Global completion.3. Well attributes4. Well filters5. Saved search

Global well logs - folder were petrel process and store well logs Global completions - folder were petrel stores completion or event data like perforations, casings diameters, plugs etc.Global observed data - folder where you can store production o volumetric data like oil gas water rates and injections.Well filters - define and store of custom well filtersSaved searches - folder to save create search of wells To be continued…