User Manual - Prescient Clean

Table of Contents

1. What is Prescient Clean..............................................................

1.1. Why Prescient Clean.....................................................................

2. Interaction with Petrel................................................................

2.1. Steps to import data from Petrel...................................................

3. Net rise velocity........................................................................

3.1. Governing Equation.....................................................................

3.2. Annular velocity...........................................................................

3.2.1. Governing Equation............................................................................. 3.3.2. Parameters required to calculate Annular velocity.............................

3.3. Cuttings slip velocity..................................................................... 3.3.1. Governing Equation............................................................................. 3.3.2. Parameters required to calculate Cuttings slip velocity......................

3.4. Parameters required to calculate Net rise velocity...................... 3.5. Annotations..................................................................................

4. Critical velocity..........................................................................

4.1. Governing Equation..................................................................... 4.2. Critical Rate of Penetration......................................................... 4.3. Parameters required to calculate Critical velocity...................... 4.4. Annotations................................................................................. 5. Cuttings bed thickness..............................................................

5.1. Governing Equation....................................................................

5.2. Parameters required to calculate Cuttings bed thickness..........

5.3. Annotations................................................................................

6. Cuttings Concentration............................................................

6.1. Governing Equation...................................................................

6.2. Maximum Rate of Penetration..................................................

6.3. Parameters required to calculate Cuttings concentration........

6.4. Annotations……………..…………………….........................................

7. Effective mud density.............................................................

7.1. Governing Equation..................................................................

7.2. Rate of Penetration...................................................................

7.3. Parameters required to calculate Effective mud density..........

7.4. Annotations……………....…………………..........................................

8. Add-ons...................................................................................

8.1. Online Glossary.........................................................................

8.1.1. Opening the Online Glossary...........................................................

8.2. Calculator.................................................................................. 8.3. Unit Converter.......................................................................... 8.3.1. Opening Unit Converter..................................................................

8.3.2. Steps to convert Units ....................................................................

8.3.3. Copy to Prescient Clean..................................................................

8.4. Hole cleaning charts: add-on....................................................

8.4.1. Hole cleaning charts........................................................................

8.4.2. Opening Hole cleaning charts: add-on............................................

8.4.3. Procedure of using hole cleaning charts: add-on............................

8.4.4. Saving the output.............................................................................

8.5. New well.................................................................................... 8.5.1. Opening New well............................................................................

8.5.2. Steps to create New well.................................................................

8.6. Quickies..................................................................................... 8.6.1. Opening a quicky..............................................................................

9. Features of Prescient clean......................................................

9.1. Exception handling.....................................................................

9.1.1. Always export the caliper log from the Petrel tree view..................

9.1.2. All the required fields must be filled to

calculate the respective output.........................................................

9.1.3. Annular velocity must be greater than cuttings

slip velocity when calculating net rise velocity.................................

9.1.4. Cuttings density must be greater than mud weight.........................

9.1.5. Hole size must be greater than the drill pipe outer diameter..........

9.1.6. Kick off point (KOP) must be less than End of build (EOB)...............

9.1.7. Kick off point (KOP) must be less than True vertical depth (TVD)....

9.1.8. End of build (EOB) must be less than True vertical depth (TVD)......

9.1.9. Wash out hole size must be greater than initial hole size................

9.2. Implicit Unit conversion..............................................................

9.3. Save & Email................................................................................ 9.3.1. Save....................................................................................................

9.3.2. Email output.......................................................................................

9.4. Automatic value detection..........................................................

Glossary

1. What is Prescient Clean?

Prescient clean is a hole cleaning analysis plug-in designed for Petrel. Prescient clean attempts to monitor hole cleaning requirements so that user may take appropriate measures as per the changing hole cleaning requirements and during the drilling process. Prescient clean intensify the functionality of petrel by importing certain Borehole parameters from Petrel project. Prescient clean also consists of various add-ons (Mail, Online Glossary, Standard Hole Cleaning Charts etc.) which make it more user friendly and intuitive.

Figure 1. Prescient clean User Interface.

1.1. Why Prescient Clean? Hole cleaning is an issue which must be considered during the planning phase of drilling operation. In order to estimate the accurate drilling time to improve the economic aspect of the drilling process. Several factors can influence hole cleaning efficiency, the most important factor for efficient hole cleaning is thoughtful planning. Effective hole cleaning is one of the major challenges in E&P industry. Prescient Clean attempts to minimize hole cleaning challenges of the E&P industry.

2. Interaction with Petrel There are several parameters which accounts for the efficient hole cleaning of the wellbore. Prescient clean imports the borehole and the associated caliper log (optional) from the petrel tree view to determine the inclination range and the diameter of the borehole respectively.

2.1. Steps to import data from Petrel

Open the plug-in from the processes tree view.

Figure 2. Prescient clean plug-in from process tree view.

If caliper log for the borehole is present.

Toggle to Petrel tree view and select the caliper log and click "Export to Prescient clean" (Plug-in will automatically detect the respective borehole for the caliper log).

Figure 3. Exporting the caliper log to Prescient Clean.

Scroll to change the Measured depth of the borehole, the plug-in will automatically the hole size for the respective depth.

Figure 4. Selecting the hole size for the respective Measure depth.

If borehole is present, but no caliper log.

Toggle the petrel tree view and select the borehole and click "Export to Prescient Clean".

Figure 5. Exporting the borehole to Prescient clean.

Note: In this case user have to enter the hole size manually.

If none is present. Prescient clean has the capability to make itself independent from Petrel. This functionality is recommended when user does have the wellbore in the petrel project.

Check "Enter data manually" to disconnect the plug-in entirely from petrel.

Figure 6. Disconnecting the plug-in with Petrel.

3. Net rise velocity The difference between Annular Velocity and Slip Velocity, with which the cuttings move from the bottom of the hole to the surface in the annulus.

3.1. Governing Equation

Vt = Va- Vs

Where, Vt is Transport velocity (Net rise velocity). Va is Annular velocity. Vs is Cuttings slip velocity.

3.2. Annular velocity The speed at which drilling fluid moves in the annulus. It is important to monitor annular velocity to ensure that the hole is being properly cleaned of cuttings, caving and other debris to avoid erosion of the borehole wall. The annular velocity is commonly expressed in units of feet per minute or, less commonly, meters per minute. The term is distinct from volumetric flow.

Figure 7. Annular velocity.

3.2.1. Governing Equation

Where,

AV is annular velocity in ft/min.

Q is flow rate in gpm (gallons per minute).

Dh is diameter of hole in inch.

Dp is diameter of drill pipe in inch.

3.2.2. Parameters required to calculate Annular velocity

Flow rate.

Hole size (if not using the Caliper Log data for wellbore).

Drill Pipe's Outer Diameter.

Figure 8. Required parameters to calculate Annular velocity.

3.3. Cuttings slip velocity

Velocity of cuttings which naturally falls down to the low-side of the hole due to their

density. In order to effectively clean the hole, effect of mud flow upward direction and mud

properties must be greater than cutting slip velocity (settling tendency of

cuttings). Otherwise, cutting will fall down and create cuttings bed.

Figure 9. Cuttings slip velocity

3.3.1. Governing Equation

For Laminar flow/Transitional flow

For Turbulent flow

where, ρp is Cuttings density in ppg. ρf is Mud weight in ppg. µe is effective viscosity of drilling fluid in cP. dp is Cuttings diameter in inches.

3.3.2. Parameters required to calculate Cuttings slip velocity

Mud weight.

Effective viscosity.

Cuttings diameter.

Cuttings density.

Flow regime (Laminar or Turbulent).

Figure 10. Required parameters to calculate Cuttings slip velocity.

3.4. Parameters required to calculate Net rise velocity

Annular velocity.

Cuttings slip velocity.

Figure 11. Required parameters to calculate Net rise velocity.

Note: If cuttings slip velocity and annular velocity is calculated by plug-in before, user is not required to enter the parameters for net rise velocity. Plug-in will automatically calculate Net rise velocity.

Figure 12. Calculation of Net rise velocity automatically if required parameters are calculated initially.

3.5. Annotations For efficient hole cleaning, Annular velocity (Va) must be greater than Cuttings slip velocity (Vs ) . It is observed that at annular velocity of less than 100 ft/min, particle slip velocity in both Newtonian and non-Newtonian fluids is independent of the fluid annular velocity. Above an annular velocity of 100 ft/min, there appears to be a dependence of slip velocity on annular velocity

Figure 13. Condition for efficient Hole cleaning.

4. Critical velocity

Critical velocity is the minimum velocity of the mud required to transport the drilled cuttings

up to the surface and keep the hole clean.


Based on the dimensional analysis conducted for cuttings bed area, critical fluid velocity

can be expressed as a function of major drilling parameters, such as :-

where,

is inclination in degrees

is Mud weight in pounds per gallon (ppg)

is viscosity of mud in centiPoise (cP)

is universal gravitational constant

Do is Hole size in inches

Di is Inner diameter of the drill pipe in inches

ROP is Rate Of Penetration in ft/hr

4.2. Critical Rate of Penetration

Prescient clean also enables user to calculate the critical rate of penetration, which is the

minimum rate of penetration to be maintained in order to clean the borehole efficiently.

Figure 14. Check the radio button to switch between critical velocity and critical ROP.

4.3. Parameters required to calculate Critical velocity

Hole angle.

Rate of penetration.

Mud weight.

Hole size.

Drill Pipe's Outer diameter.

Viscosity.

Figure 15. Required parameters to calculate Critical velocity.

Note: To calculate critical ROP, user have to enter critical velocity manually rest of the required parameters will remain same.

4.4. Annotations If inadequate flow rate is used, cuttings will settle on the low-side hole and form a large stationary bed which may result in severe drilling problems such as high drag and torque, hole packing-off and stuck pipe. All these may subsequently require expensive remedial operations and thus incur substantial increases in drilling cost. It Is crucial to know the Critical Flow rate when planning and drilling a deviated well so that the adequate and economical drilling equipment can be selected and optimum parameters determined.

5. Cuttings bed thickness In deviated wells, the cuttings are no longer fully supported by fluid drag or when the drilling fluid circulation is stopped or is low due to this phenomena cuttings concentrate on the low-side of the hole in the form of a bed. The thickness of the stationary bed developed when Fluid Velocity is lesser than Critical Velocity and hence due to settlement of cuttings is called cuttings bed thickness.

Figure 16. Flow patterns for solids/liquid in high angle and horizontal annulus.


Where,

where,

5.2. Parameters required to calculate Cuttings bed thickness

Cuttings diameter.

Flow rate.

Hole angle.

Rate of penetration(ROP).

Mud weight.

Rotation.

Hole size.

Drill Pipe outer diameter.

Viscosity.

Figure 17. Required parameters to calculate Cuttings bed thickness.

5.3. Annotations If the circulation rate is very low, cuttings are unlikely to be removed from the well bore. Upon increasing the flow rate, the bed formed cue to settlement of cuttings becomes progressively eroded. The mobile cuttings on the interface salt ate and form dunes or large ripples. The bed then starts to move and cuttings are cleaned from the well bore. It can be seen that the thickness of cuttings layer decreases with increase of the flow rate as a whole. It means that increasing flow rate is required for efficient hole cleaning.

6. Cuttings Concentration

Volume of fraction of cuttings (or concentration) coming to the surface along with the

drilling fluid.

Figure 18. Cuttings concentration.


where, Cc is Cuttings concentration in percentage (%). ROP is Rate of penetration in ft/hr. Va is the Annular velocity in ft/min. Vs is the Cuttings slip velocity in ft/min. Dh is the Borehole diameter in inches. ODp is the Drill pipe outer diameter in inches.

6.2. Maximum Rate of Penetration Maximum Rate of penetration is the rate of penetration which should not be exceeded during drilling in order to minimise hole problems. Prescient clean also enables user to calculate maximum Rate of penetration on the basis of governing equation (6.1), the cuttings concentration is taken 5% in order to calculate Maximum ROP.

Figure 19. Check the radio button to switch between cuttings concentration and maximum ROP.

6.3. Parameters required to calculate Cuttings concentration

Rate Of penetration (ROP).

Hole size.

Cuttings slip velocity.

Annular velocity.

Drill Pipe outer diameter.

Figure 20. Required parameters to calculate Cuttings concentration.

Note: To calculate Maximum ROP, cuttings concentration is taken 5% by default.

6.4. Annotations To prevent hole problems, it is generally accepted that the volume fraction of cuttings (or concentration) in the annulus should not exceed 5%. Prescient clean takes the cuttings concentration, 5% by default in order to calculate Maximum Rate of penetration.

7. Effective mud density Effective mud density is the cumulative mud density which takes into account the total mass as well

as the volume of both mud and the drilled cuttings. It comes into effect after the mud carries away

the drilled cuttings to the surface along with it.


In Symbol form :-

where, ρeff is effective mud density in hole in pounds per gallon (ppg). ρm is density of mud at surface in pounds per gallon (ppg). Q is mud flow rate in gallon per minute (gpm). ROP is rate of penetration in ft/hr. db is the drill bit size (= hole size) in inches.

7.2. Rate of Penetration Prescient clean also enables user to calculate Rate of penetration on the basis of governing equation (7.1), user have to enter the effective mud density manually in order to calculate respective Rate of penetration.

Figure 21. Check the radio button to switch between effective mud density and rate of Penetration.

7.3. Parameters required to calculate Effective mud density

Flow rate.

Mud weight.

Hole size.

Rate of penetration.

Figure 22. Required parameters to calculate Effective mud density.

Note: To calculate Rate of Penetration, user have to enter effective mud density manually rest of the parameters will remain same.

7.4. Annotations Increase in annular mud density i.e. effective mud density shows that the drilled cuttings are

being coming up to the surface along with drilling mud and hole is being cleaned. Increases

in annular mud weight due to drilled cuttings loading can result in formation breakdown,

particularly in surface holes. The increase in annular mud weight due to drill cuttings must

be calculated and taken into account. It may be necessary to reduce the ROP in order to

keep the annular mud density to an acceptable value.

8. Add-ons

Prescient Clean consists of various add-ons (tools), which intensifies the functionality of the

plug-in and hence, Petrel. The add-ons in the plug-in are as follows :-

Online glossary.

Calculator.

Unit converter.

Hole cleaning charts.

New well.

Quickies.

Figure 23. Prescient clean Add-ons.

These add-ons might be used more frequently by the user as compared to Prescient clean plug-in itself, taking this scenario into consideration these tools have been integrated to the main Menu of the Petrel, so that user doesn't have to take the pain of opening the plug-in to make use of these add-ons.

Figure 24. Prescient clean Add-ons in the Petrel Main Menu.

Note: Shortcuts keys will work if Prescient clean main window is opened.

8.1. Online Glossary There are numerous terms in an oil and gas industry about which user doesn't have any idea. This add-on helps you knowing the meaning of such terms by searching the word over Schlumberger oil field online glossary. Prescient clean adds the new online glossary window to the collection of existing Petrel windows.

Figure 25. Online Glossary window Add-on.

8.1.1. Opening the Online Glossary Online Glossary can be opened in the following ways :-

From Windows Sub menu in Petrel main Menu.

Figure 26. Opening online Glossary window from Windows Sub Menu.

From PC Tools Sub menu in Petrel Main Menu.

Figure 27. Opening online Glossary window from PC Tools Sub Menu.

From Tools Sub menu in Prescient clean Main Menu (Shortcut: Ctrl + G).

Figure 28. Opening online Glossary window from PC Tools Sub Menu.

Note: Online Glossary is powered by Schlumberger oil field Glossary, Copyright of Schlumberger Inc.

8.2. Calculator Default windows calculator is one of the oldest and most widely used PC applications, it is often very tedious to open the windows calculator through the long conventional procedure. Using Prescient clean you don't have to follow the long old procedure to open windows calculator. Plug-in integrates calculator as one of it tools and it can be opened as any other add-on for Prescient clean. (Shortcut: Alt + C)

Figure 29. Opening calculator from Prescient clean Main Menu and Petrel Main Menu.

8.3. Unit Converter Unit converter add-on for Prescient clean lets you convert numerous units related to drilling and production easily.

Figure 30. Unit Converter Add-on.

8.3.1. Opening Unit Converter (Shortcut: Ctrl + U)

Figure 31. Opening Unit converter from Petrel main menu and Prescient clean main menu.

8.3.2. Steps to convert Units

Open a unit converter window.

Choose a conversion type from "Choose a conversion type" drop down list menu.

Choose a unit from "Unit Type" drop down list menu.

Enter the value to be converted in "Convert From" text box and hence select the input unit from the "Convert From" list box.

Select the output unit from the "Convert To" list box.

Output.

8.3.4. Copy to Prescient Clean

Unit converter gives you an option to export the output of conversion to main Prescient clean window on a click, e.g. If you convert Rate of penetration from Feet per day to Meter per day and clicks "Copy to Prescient clean", all the Rate of penetration parameters in the main window will be filled automatically.

Steps to copy value to Prescient clean

Convert the input to desired output (Sec. 10.2). Click "Copy to Prescient Clean".

As soon as you click the button "Parameter Dialog" dialog will appear. Select the parameter you want to fill with the value and then press OK.

Figure 32. Rate of penetration value, copied directly from Unit converter.

Note: Parameter dialog will not be prompt if the unit which is converted is not present in the parameters in the main window of the prescient clean, e.g. Yield slurry parameter is not present in the Prescient clean main window it can't be exported to Prescient clean main window on the click of "Copy to Prescient clean" button. Note: "Copy to Prescient Clean" button will work only if user has opened Unit Converter from Prescient Clean main menu but not from Petrel main menu.

8.4. Hole cleaning charts: add-on Using this add-on user can determine the critical flow rate to keep the hole clean using standard hole cleaning charts. These can be used by drilling engineers at the rig-site to optimise hole cleaning for drilling various hole sections of a deviated well.

Figure 33. Hole cleaning charts Add-on.

8.4.1. What is Hole cleaning charts ? Based on the typical drilling conditions in the BP's operating areas in the North sea, sensitivity analysis was carried out by using the full model to examine the key variables which can be adjusted during the planning or drilling stage of a deviated well. Based on the analysis, the effects of each of the variables on hole cleaning was established for each of the hole sizes. For the mud PV and YP, it was found that a single parameter called the Rheology Factor(RF) can be used to describe their effects. The higher the RF, the more effective the mud rheology for hole cleaning. In order to determine the value of the RF from the mud PV and YP, a set of charts was derived for 17-1/2, 12-1/4 and 8-1/2 hole sizes. The effect of the hole angle was approximated by a group of factors called the Angle Factor(AF). The higher the hole angle, the lower the AF value, the more difficult the hole cleaning.

Figure 34. Angle factor for deviated holes.

The effect of the mud weight(MW) was combined together with the RF and AF to form a single parameter called the Transport Index(TI). TI = RF x MW x AF where, MW is in S.G. or g/cm3

The interaction between the ROP and the CFR can be mapped on a chart but linkage to the TI should be established in order to reflect the effects of all the other variables. This has been done by other set of charts for 17-1/2, 12-1/4 and 8-1/2 hole sizes.

Figure 35. Hole cleaning charts for 17-1/2 inch hole.



Effect of Hole washout: The hole cleaning charts have been derived for three different hole sizes. However, it is sometimes the case that the part of the open hole section is enlarged (washed out) and to transport cuttings through this wash out, a higher mud flow rate will be required. Final critical flow rate for washed out hole is given by :-

(

)

where, Q1 is initial flow rate in gpm. Q2 is final flow rate in gpm. DNew is washout hole size in inches. DOld is initial hole size in inches.

8.4.2. Opening Hole cleaning charts: add-on (Shortcut: Ctrl + H)

Figure 38. Opening Unit converter from Petrel main menu and Prescient clean main menu.

8.4.3. Procedure of using hole cleaning charts: add-on

Select the appropriate hole size, for which you want to determine critical flow rate or Maximum safe Rate of Penetration.

Enter the rheology factor chart, read off the rheology factor.

Read off the angle factor for the respective hole angle from Table and select the angle factor from the drop down list.

Enter Mud weight and Rheology Factor. Calculate the Transport Index by clicking the "Transport Index" button.

Enter the hole cleaning chart for the critical flow rate, with TI and desired ROP read off the critical flow rate for hole cleaning.

If hole is washed out, check "Is Hole wash out ?" check box.

Enter Initial critical flow rate calculated by reading off the value from chart and wash out Hole size.

Click "Final critical flow rate" button.

8.4.4. Saving the output User can save the output as the PDF document by clicking save button for the later reference.

8.5. New well New well add-on lets you create a new wellbore in the Petrel current project. Moreover the new well bore created by the user will automatically be added to the Prescient clean for the further calculations about the hole cleaning requirements for the newly created borehole.

Figure 39. New well Add-on.

8.5.1. Opening New well (Shortcut: Ctrl + W)

Figure 40. Opening New well add-on from Prescient clean Main Menu and Petrel Main Menu.

8.5.2. Steps to create New well

Enter the compulsory parameters.

Figure 41. Opening New well add-on from Prescient clean Main Menu and Petrel Main Menu.

Note: Compulsory parameters have to added for the wellbore of all profile types.

Select the well profile.

Enter the parameters for the respective well profile.

Note: The parameters which are not required to build the selected well profile are disabled automatically.

Click "Export to Petrel" Button.

Figure 42. Well created using New well add-on.

Note: The wellbore created using New well add-on will only be added to Prescient clean automatically if the add-on is opened from the Prescient clean main menu but not from Petrel main menu, otherwise user have to add the wellbore to Prescient clean in the conventional way from the Petrel tree view.

8.6. Quickies This is the simplest but useful add-on of the Prescient clean. User can write the temporary notes or reminders over the quicky and can later save the quicky as a text file by clicking "Save" button.

Figure 43. Quicky add-on.

8.6.1. Opening a quicky

Figure 44. Opening a Quicky from Petrel main menu and Prescient clean main menu.

9. Features of Prescient clean Prescient clean incorporate numerous features which makes it more user friendly and easier to use. Features of the Prescient clean are as Follows :-

Exception Handling

Email & Save

Implicit unit conversion

Automatic value detection

Tools tips

9.1. Exception handling Exception handling feature makes plug-in more intelligent, because of this feature user will be prompt every time the invalid value is being filled by the user in the form and hence, it will prevent the generation of wrong output. The exception will be raised in the following cases :- 9.1.1. Always export the caliper log from the Petrel tree view If user imports any other log like litho log, gamma log etc apart from caliper log for the respective well the exception will thrown.

Figure 45. Exception thrown when importing any other log apart from caliper log.

9.1.2. All the required fields must be filled to calculate the respective output To calculate any output let's say annular velocity user have to fill in all the required parameters within the group box which contains all the parameters requires to calculate annular velocity otherwise an exception will be thrown, same is applicable to all the expected output values.

Figure 46. Exception thrown when user doesn't fill in the required parameters within the group box, required to calculate annular velocity.

9.1.3. Annular velocity must be greater than cuttings slip velocity when calculating net rise velocity If user enters the cuttings slip velocity greater than annular velocity the exception will be thrown, (Refer Sec. 3.1.), if annular velocity is not greater than cuttings slip velocity the resultant net rise velocity will be negative which is mathematical error and moreover, it signifies that cuttings are settling down at the low-side of the borehole. Hence, for proper hole cleaning net rise velocity must be positive.

Figure 47. Exception thrown when annular velocity is less than cuttings slip velocity.

9.1.4. Cuttings density must be greater than mud weight If user enters the cuttings density value greater than mud weight while calculating the cuttings slip velocity, the exception will be thrown. This is because it is obvious that mud density (weight) (ratio of mass of the mud and volume of the mud) will always be greater than the cuttings density (ratio of mass of the cuttings and volume of the cuttings) since, cuttings are always carried up to the surface along with the mud (Refer Sec. 3.3.1).

Figure 48. Exception thrown when Mud density is less than cuttings density.

9.1.5. Hole size must be greater than the drill pipe outer diameter If user enters the hole size value less than drill pipe outer diameter, the exception will be thrown. Since drill pipe is the part of drill string which drills down the bore hole it can never be greater than hole size in any case.

Figure 49. Exception thrown when Hole size is less than Drill pipe outer diameter.

9.1.6. Kick off point (KOP) must be less than End of build (EOB) In new well add-on, if user enters the KOP depth greater than EOB depth, the exception is thrown.

Figure 50. Position of KOP and EOB in the wellbore.

Figure 51. Exception thrown when KOP is greater than EOB.

KOP

EOB

9.1.7. Kick off point (KOP) must be less than True vertical depth (TVD) In new well add-on, if user enters the KOP depth greater than True vertical depth, the exception is thrown.

Figure 52. Position of KOP, EOB and TVD in the wellbore.

9.1.8. End of build (EOB) must be less than True vertical depth (TVD) In new well add-on, if user enters the EOB depth greater than True vertical depth, the exception is thrown.

Figure 53. Exception thrown when, TVD is less than EOB.

KOP

TVD

EOB

9.1.9. Wash out hole size must be greater than initial hole size In hole cleaning charts add-on, if user enters the wash out hole size less than the initial hole size the exception is thrown, since it is impossible to be wash out size less than well bore.

Figure 54. Exception thrown when, Wash out size is less than hole size.

Note: The back ground of the required field turns blue in colour if it is left unfilled by the user. Note: The back ground of the field with invalid value turns red.

9.2. Implicit Unit conversion Prescient clean allows user to input parameters in numerous units and take the output in the desired unit. This makes prescient clean compatible with all the units followed by different countries around the globe. To get the output in the desired units select the unit from the "output unit" drop down list.

Figure 55. Select unit from annular velocity drop down list to get the result in the desired unit.

9.3. Save & Email These features helps the user to preserve the generated output for the later reference. 9.3.1. Save User can always save the generated result as a PDF document by clicking "Save Output" button in Prescient clean main menu. Drilling engineers may later refer to the document to monitor the drilling parameters for efficient hole cleaning. (Shortcut: Ctrl + S)

Figure 56. Email output window.

9.3.2. Email output This features enables user to e-mail the generated output to the other person. (Shortcut: Ctrl + M)

Steps to send Email Open Mail window by clicking "Mail Output" button.

Enter the email id of the other person to which email have to be sent.

Note: Multiple email addresses must be separated with comma followed by space ", " character e.g. "[email protected], [email protected]".

Click "Send" button, wait for 1 minute, if message sending is successful

"Message Sent" will appear on the right side of the status bar.

Note: Mail output window automatically imports the output generated by the user from the Prescient clean main window user doesn't have to write the generated output in the message body.

9.4. Automatic value detection Automatic value detection feature minimises the user input, it automatically fills all the fields with the same value, once user enters the value in the any of the field with same notation. e.g. If user enters the hole size 12.25 inches in Annular velocity group box, all the other hole size fields will be filled with that value automatically.

Figure 57. Auto update of hole size value in cuttings concentration tab page, once entered in annular velocity group box.

Note: The value will be updated to other fields after the calculation of one parameter, e.g. annular velocity in this case.

Glossary Borehole: the hole made by drill bit, also referred as hole, well or wellbore.

Build up rate: the rate at which drift angle is increasing as the wellbore is being deviated

from vertical.

Build up section: the part of wellbore's trajectory where drift angle is increasing.

Caliper log: a tool run on electric wire line which measures the diameter of the wellbore. it

may be used for detecting washouts, calculating cement volumes or selecting internal

corrosion of casing.

Critical Rate of penetration (ROP): At a given maximum mud flow rate, as is often the case

when drilling a deviated well, there is a maximum allowable ROP at which the well can be

safely drilled known as the critical ROP and is used as a useful tool for optimizing hole

cleaning and at the same time maximizing drilling efficiency.

Cuttings: the fragments of rock dislodged by the bit and carried back to the surface by the

drilling fluid (mud).

Cuttings concentration: volume of fraction of cuttings (or concentration) coming to the

surface along with the drilling fluid.

Cuttings density: density of the fragments of rock dislodged by the bit and carried back to

the surface by the drilling fluid (mud).

Cuttings diameter: diameter of the fragments of rock dislodged by the bit and carried back

to the surface by the drilling fluid (mud).

Drilling fluid: the fluid which is circulated through the drill string and up the annulus back to

the surface under normal drilling operations. usually referred as mud.

Drill pipe: a heavy seamless pipe which is used to rotate the bit and circulate the drilling

fluid. lengths of drill pipe (30 ft) long are couple together with tool joints to make drill string.

Drill pipe OD: outer diameter of heavy seamless pipe which is used to rotate the bit and

circulate the drilling fluid.

Effective mud density: Increase in the annular mud weight due to drilled cuttings loading,

while drilling.

End of build: the depth at which build up section of the wellbore ends.

Effective viscosity, µ (cP): This term takes account of the geometry through which the fluid

is flowing and is therefore a more descriptive term of the flowing viscosity or The Effective

Viscosity is the actual viscosity of the fluid at the shear rate which exists in the pump and

pumping system at the design condition.

Flow rate or volumetric flow rate: is the volume of drilling fluid (Mud) which passes through

a given surface per unit time. The SI unit is m3·s−1(cubic meters per second). Volumetric flow

rate is often expressed as ft3/s (cubic feet per second). It is usually represented by the

symbol Q Volumetric flow rate can also be defined by:

Flow Regime: There are three basic types of flow regimes:

Laminar flow: In laminar flow, fluid layers flow parallel to each other in an orderly fashion. This flow occurs at low to moderate shear rates when friction between the fluid and the channel walls is at its lowest. This is a typical flow in the annulus of most wells.

Turbulent flow: This flow occurs at high shear rates where the fluid particle move in a disorderly and chaotic manner and particles are pushed forward by current eddies. Friction between the fluid and the channel walls is highest for this type of flow. This is a typical flow inside the drill pipe and drill collars. Unlike laminar flow, mud parameters (viscosity and yield point) are not significant in calculating frictional pressure losses for mud in turbulent flow.

Transitional flow: Occurs when the fluid flow changes from laminar to turbulent or vice versa.

Hole angle: a measure of the angular deviation of the wellbore from vertical (inclination).

Sometimes referred as drift angle.

Hole size: diameter of borehole.

KOP abbr. Kick-off Point: The depth at which the wellbore is deliberately deviated from

vertical.

Measured depth (MD): the distance measured along the path of the wellbore.

Mud weight: density of the fluid which is circulated through the drill string up the annulus

back to the surface under normal drilling operation.

Reference level: is the elevation from the ground i.e. a datum line or the point of reference

from which the depth of a well or a target reservoir is measured Common references used

in operations include: Rotary Table (RT), Drill Floor (DF), Mean Sea Level (MSL), Kelly

Bushing (KB), Sea Bottom (SB), Ground Level (GL), Casing Bowl Flange (CBF).

Rheology factor (RF): is a direct indication of how effective the mud rheology is in terms of

hole cleaning: the higher the RF, the more effective the mud rheology. So one can maximize

RF in order to improve hole cleaning.

ROP: Rate of penetration, abbreviated as ROP as used in the drilling industry, is the speed

at which a drill bit breaks the rock under it to deepen the borehole or simply may be

described as the speed of drilling. Also known as penetration rate or drill rate. It is normally

measured in feet per minute or meters per hour, but sometimes it is expressed in minutes

per foot. Generally, ROP increases in fast drilling formation such as sandstone (positive drill

break) and decreases in slow drilling formations such as shale (reverse break).

Rotation Per Minute (RPM): Revolutions per minute (abbreviated rpm, RPM, r/min,

or r·min−1) is a measure of the frequency of a rotation. It annotates the number

of turns completed in one minute around a fixed axis. It is used as a measure of rotational

speed of a mechanical component like drill string.

True vertical depth: total vertical depth of the wellbore.

Viscosity: a measure of fluid's resistance to flow. The resistance is due to internal friction

from the combined effects of cohesion and adhesion.

Washout: wellbore enlargement due to solvent or erosion action of drilling fluid.

Wellhead: the equipment installed at the top of the wellbore from which casing and tubing

strings are suspended.

Wellhead X: X coordinates of well head.

Wellhead Y : Y coordinated of well head.

Well profile: the path followed by the wellbore to reach the target, also referred as well

trajectory.

User Manual - Prescient Clean

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