USER MANUAL 6 · 2016. 12. 8. · Drillbench Hydraulics User Guide Page ii 4.3.6 Export of charts 49 4.3.7 Help 51 4.3.8 About 51 5. Appendix: Technical documentation 52 5.1 Hydraulics

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_USER MANUAL 6 .0

HYDRAULICS

Drillbench Hydraulics User Guide Page i

TABLE OF CONTENTS

Page

1. INTRODUCTION 1

2. INPUT 3 2.1 Input parameters 3 2.2 The input file 3

2.2.1 Library 3 2.2.2 Range checking 4

2.3 Input navigators and menu bars 5 2.3.1 Description 5 2.3.2 Survey 6 2.3.3 Formation 8 2.3.4 Pore pressure and Fracture pressure 10 2.3.5 Wellbore geometry 11 2.3.6 String 14 2.3.7 Mud 15 2.3.8 Temperature 24

2.4 Expert Input Parameters 25 2.4.1 Model parameters 26 2.4.2 Eccentricity 27 2.4.3 Surface pipeline 27 2.4.4 RCH and choke 29

3. CALCULATION AND OUTPUT 30 3.1.1 Hydraulics 30 3.1.2 Surge & swab 31 3.1.3 Sensitivity analysis 33 3.1.4 Bit optimization 34 3.1.5 Volumetric displacement 35

4. MENUS AND TOOLBARS 37 4.1 File 37

4.1.1 New 37 4.1.2 Import 37 4.1.3 Export 38

4.2 View 38 4.2.1 Well schematic 39 4.2.2 Survey plot 39 4.2.3 Log view 40 4.2.4 Navigation bar 41 4.2.5 Input 41 4.2.6 Expert input 41 4.2.7 Simulation 41

4.3 Tools 41 4.3.1 Take snapshot 41 4.3.2 Report 41 4.3.3 Validate parameters 45 4.3.4 Edit unit settings 46 4.3.5 Options 46

Drillbench Hydraulics User Guide Page ii

4.3.6 Export of charts 49 4.3.7 Help 51 4.3.8 About 51

5. Appendix: Technical documentation 52 5.1 Hydraulics 52

5.1.1 Adjustment of density 52 5.1.2 Adjustment of rheology 52 5.1.3 Input and output 54

5.2 Hole cleaning 54 5.2.1 Moore correlation 54 5.2.2 Zhou model: Horizontal and inclined wellbore 57 5.2.3 Input and output 58

5.3 Surge and swab 59 5.3.1 Input and output 59

5.4 Sensitivity 59 5.4.1 Input and output 59 5.4.2 Bit optimization 59 5.4.3 Maximum bit nozzle velocity 60 5.4.4 Maximum bit hydraulic power 60 5.4.5 Maximum jet impact force 61 5.4.6 Optimization with Hydraulics 62 5.4.7 Input and output 62

6. KEYBOARD SHORTCUTS 63

7. ACKNOWLEDGEMENT 64

8. REFERENCES 65

Drillbench Hydraulics User Guide Page 1

1. INTRODUCTION

Hydraulics is a tool for performing steady state computations of hydraulic parameters in an oil well during drilling operations. Computations of pressure, equivalent viscosity, velocity & ECD during drilling are performed in the Hydraulics mode. In Surge & swab, computations of pressure, ECD, return rate & max string movement are performed. There are also options for performing Bit optimization, and computations of Volumetric displacement for a sequence of fluid flows. The application also includes an easy to use Sensitivity analysis feature.

The Hydraulics user interface consists of 4 main areas; the menu line and the toolbar at the top of the window, and in the main Hydraulics window there is a navigation bar to the left and a data entry window to the right, as shown in Figure 1-1.

There are three navigation groups: Input and Expert input for input navigators and a simulation navigator. The data entry window displays either input parameters or computed output parameters depending on selected navigator.

To enter input, choose the input navigators, to compute, choose calculation navigators.

Figure 1-1: Navigation menu bar and data entry window.

The menu line

A standard menu line with File, Edit, View, Results, Tools and Help entries. File operations, selecting views and simulation control may be done from here.


The toolbar

Standard commands like File New, File Open, Save, Copy, Cut and Paste , are placed in a toolbar for easy access. These commands can also be accessed by standard Windows keyboard shortcuts (ref. Chapter 6).

Navigation bar

The navigation bar contains:

- Input for specification of the most frequently used input parameters

- Expert input for specification of optional or expert features

- Simulation for calculation and output of results

Data entry window

Displays either input parameters or calculated output parameters depending on the current selection in the navigation bar.


2. INPUT

2.1 Input parameters

Before computations can be performed, essential input must be entered in the data entry views, or loaded from an input file. To enter the data, select one of the input navigators. Input is given in seven data entry views entered by clicking the corresponding navigators.

2.2 The input file

The input file contains all the data describing the case. However, operational parameters such as pump rate and ROP must be given directly in the simulation windows.

A new case can either be created by building a new file or by editing an old file. The data needed for a simulation may be selected from the library or specified in the input parameter sheets. Details about the input parameter sheets and the library are presented in more details in section 2.3.

If you have used older versions of Drillbench, you can open your input files as normal and you will be notified that your input has been upgraded. Note that this upgrade is irreversible – files saved from this version cannot be loaded in older versions of Drillbench.

When using Hydraulics to create an input file, default values are assumed for the formation parameters and the physical models. The default values are chosen to fit the "typical case". Select New from the File menu to generate a new input file.

Input files created with other Drillbench applications can also be used in Hydraulics, since all Drillbench application share the same data model.

2.2.1 Library

Data is entered in the parameter input section. Some of the input data can be selected from a library.

The library is a tool for reuse of data and it contains information about fluids, pipes, casings and tools that is likely to be used in many operations. The case specific data are entered in the parameter input section. This is typically survey data, operational conditions and temperature data. The entries from the library are selected in the parameter input sections for “Wellbore geometry”, “String” and “Mud”.

The items/components that can be found and stored in the library are:

Riser

Casing/Liner

String components

Bit


Mud (Drilling fluid)

The find a specific item or component in the library it is set up with an option to filter out some specific items or components. You can set up several different filters to make your library search more detailed if preferred. If you choose not to use the filter option, all items or components in the library will be listed for the specific category.

If you do not find a suitable item or component in the library, you can specify all the properties of the item or component manually and then add the item or component to the library by right-clicking on the name.

Figure 2-1: Library browser for casings.

2.2.2 Range checking

Most input parameters have a defined minimum and maximum value range. If an entered value is outside its range, Hydraulics highlights the value by setting the background color of the input field to light red. The valid range is shown in the status bar at the bottom of the window when pointing the mouse at the invalid field.


2.3 Input navigators and menu bars

The navigation bar to the left of Figure 1-1 is described in the following sections. The input navigators are summarized below.

Summary A brief summary of the most important input data

Description Information about the present study/case

Formation Defines the formations and geothermal properties

Pore pressure & Fracture pressure

:Defines pore- and fracture pressure with depth

Survey Describes the well trajectory

Wellbore geometry Defines the casing program for the well

String Configuring and defining the drill string and bit

Mud Defines the drilling fluid

Temperature Defines temperatures and temperature model

To add or remove rows in tables, use the following commands:

• Ctrl+Ins : add a new row for defining additional casings, while

• Ctrl+Del : delete a row

Hints are shown in the status bar at the bottom of the window when pointing the mouse at tables.

2.3.1 Description

Use the Description window to specify the current case. The input is self-explanatory and consists of the essential information needed to identify the case. Use the comment line to distinguish several computations performed for the same case.


Figure 2-2: Description window.

2.3.2 Survey

The input data for the survey are measured depth, inclination and azimuth. The simulator calculates the true vertical depth (TVD) by using the minimum curvature algorithm. The angle is given as deviation from the vertical, which means that an angle of 90° indicates the horizontal. The angle between two points is the average angle between the points. The simulator handles horizontal wells, but angles higher than 100° are not recommended. This window is optional and the well is assumed vertical if no data is entered.


Figure 2-3: Specification of survey data.

The survey data can be entered manually, copied from a spread-sheet or imported from an existing survey file. Figure 2-4 show the survey data table and a 2D sketch of the well trajectory.

Inclination data can also be imported from file (Ref.Figure 2-4) by choosing File Import Survey data or Petrel well path.

Figure 2-4: Menu option for survey data import.


The Petrel well path option opens a File open window and a well path file can be selected.

The survey data import is different as this option opens a file import application as shown in Figure 2-5.

The import application is very general and can handle different units, different column order or delimiter. It can also handle a various number of header or footer lines.

Figure 2-5: Survey Import window.

The survey profile can be previewed in 3D, by selecting View Survey plot.

2.3.3 Formation

The formation input contains all information about the environment where the well is going to be drilled. Different horizontal layers are defined together with the properties for each layer.

For offshore wells at least two lithologies are required: seawater and formation. If more detailed knowledge about the geology and thermophysical properties of the different geological layers are available, several formation layers with different properties can be defined.


Seawater specification can also be differentiated. Especially for deep-water wells this can be of importance. It is possible to select different temperature (geothermal) gradients at different water depths.

Default values are given for seawater and formation. However, it can be necessary to change the defaults, since the geothermal gradient is defined as a material property. It is important to note that even if other properties are the same - if the geothermal gradient changes a new lithology should be defined.

The window consists of five columns. The first three specifies the name and the top and bottom depths. Column 4 contains geothermal gradient. Column 5 contains an option to edit the properties for the different layers. The properties are set with default values and should only be changed if other values are to be used.

Figure 2-6: Formation input window.


Figure 2-7: 3D survey plot.

2.3.4 Pore pressure and Fracture pressure

This optional window defines the pore pressure and the corresponding fracture pressure for various depths.

You can import Techlog LAS pore & fracture pressure via the Import command on the File menu.

Give measured depth and the corresponding pore pressure gradient in the upper table, and measured depth and corresponding fracture pressure gradient in the lower table. The corresponding TVD values are displayed for information purposes.

The pore- and fracture pressure gradients are plotted to give a means of graphical verification of the input.


Figure 2-8: Specification of pore pressure & fracture pressure.

2.3.5 Wellbore geometry

This window defines the casings used throughout the study (see Figure 2-9

Casing types are selected from the Library. Select from the drop down list in the first column. Once a casing type is selected, the hanger and the setting depth must be given. A sketch of the casing design can be plotted on the right side of the window.

Figure 2-9: Specification of Riser, casing and liner data.


Riser

Figure 2-10: Riser.

The riser is specified by the length (water depth) and the riser type. The list for riser type refers to entries in the library.

Figure 2-11: Library browser for Casings and Risers.

Casing/Liner

Due to the fact that the temperature model is two-dimensional, it is normal to include all the casings and the materials surrounding them in the specification of the well. If the dynamic temperature model is not going to be used, it is enough to specify the innermost layer of casings and liners, and data in the columns “Hole diameter”, “Top of cement”, and “Material above cement” will not be used.


Figure 2-12: Casing/Liner.

Each row in the casing and liner window is used for specifying the information necessary for one casing string.

The first column contains the casing/liner name. This is a drop down button with reference to the casing and liner library. All the information about dimensions and properties are taken from the library.

The second column is the hanger depth. It specifies the starting point of the casing. The hanger depth will often be equal to the water depth. If there are deeper liners, the hanger depths for these should be specified as well.

The third column is used to specify the setting depth for the casing.

In the fourth and fifth column the inner and outer diameter of the casing is specified (these values will be taken from the library, but can be manually updated as well).

In the sixth column the hole diameter outside the casing is specified.

In the seventh column the top of cement is specified. The eighth column is specifying the material above the cement. Note that even if it is cemented to the seabed, there will be a seawater column on top of the cement.

The last column has an option to manually update some properties of the casing, including thermophysical properties.


Figure 2-13: Properties of casing.

Open hole

The open hole length and diameter are defined implicitly by the string length and the bit diameter.

2.3.6 String

You may choose to use tool joints in the calculations. You must then specify an average stand length in order to let the program calculate the numbers of tool joints.

Figure 2-14: Average stand length and tool joints.

Select components from the library browser to configure the drill string. The selection is performed from a drop down list in the first column of the table. All components, including the bottom hole assembly (BHA) are defined from the bit and upward in this table.

Figure 2-15: String configuration.

It is possible to create items with custom dimensions by modifying diameters of an already defined item. Note that this is only intended for testing items that are not defined in the library. To add new items to the library, right click on the component.

It is also possible to edit/view the properties of the different components by clicking in the last column of the chosen component.


Figure 2-16: Properties for components.

The bit is defined separately. Select the bit from the library browser by picking from the drop down list. It is possible to edit the bit dimensions and properties. The flow area through the nozzles is defined either by entering the total flow area (TFA) or by entering the diameter of each nozzle. To add a newly created bit to the library, click on the Add to library button.

Figure 2-17: Bit configuration.

2.3.7 Mud

The appropriate drilling fluid is selected from the library from the drop down menu in the mud window. If the desired drilling fluid is not available in the library, the drilling fluid has to be properly defined using the input fields for component densities, PVT, Thermophysical properties and rheology. The newly created drilling fluid can be added to the library by using the Add to library button in the upper right corner.


Figure 2-18: Mud window.

Component densities

Below the drilling fluid entry, the fluid component densities are displayed.

Unless the fluid density is calculated based on data from a field mud, see Measured PVT model below, a component density model is used. In this case, the p, T dependency of each phase will be treated separately, and a resulting density will be calculated based on the weight fractions of each phase and the density of the mud at standard conditions.

Base oil density and water density are specified at standard conditions (1 bar,15°C / 14.7 psia and 60 °F).

Solids density is the density of the weight material. A solid density of 4.2 sg is suggested by default, which corresponds to the density of barite. In these calculations, the compressibility of solids is assumed to be negligible, an assumption that in most cases is fairly correct.

Density refers to the density of the whole mud phase and must be specified at the corresponding reference temperature and atmospheric pressure.

The last parameter to be specified is the mud Oil/water ratio. The ratio is specified as 'oil volume%/water volume%' (e.g. '80/20').


Figure 2-19: Component densities.

PVT model

Two different PVT models are available, Measured PVT model or a Density correlations PVT model. The model is selected from the PVT model dropdown list.

Figure 2-20: PVT model.

Measured

The measured PVT model is based on measured fluid and oil density data for different pressure and temperatures. The measured values can be specified by clicking on the PVT properties button in the PVT section.


Clicking the properties button opens a sub-window with two tab sheets; one for density of the whole fluid and one for density of the base oil.

Figure 2-21: Specification of PVT data for measured PVT option.

Both tab sheets contain spreadsheet tables that support copy and paste between other programs and Drillbench.

Mud density

The table for mud density consists of a spreadsheet component with temperature data in the first row and pressure in the first column. The densities are filled in for each pair of pressure and temperature. This table is not needed unless Measured PVT is chosen as PVT model.


Figure 2-22: PVT-window.

Base oil density

The table for base oil density consists of a spreadsheet component with temperature data in the first row and pressure in the first column. The densities are filled in for each pair of pressure and temperature. This table is not needed unless Measured PVT is chosen as PVT model.


Density correlations

Figure 2-23: Density correlations PVT model.

Oil density submodel

Three models (Sorelle(oil), Glassø, Standing) are available, these are based on experimental work on different oil samples. There is also a possibility to enter measurements on the actual fluid.

Standing : The Standing model was originally presented in 1947. The correlations were formulated based on experimental work on Californian oils, and were since reformulated in 1974.

Glassø (recommended): The Glassø model is similar to the Standing model, but it is formulated for North Sea oils. Both the Standing and Glassø models are valid only for the low to moderate pressure range. Above this, in the high pressure and temperature range, the Vazques and Beggs model (Reference III) is used.

Sorelle (oil): The Sorelle model is based on laboratory measurements of diesel oil. The model is formulated for HPHT conditions.

Table: The table approach uses the PVT properties spreadsheet component, as described in the section above under Measured PVT model, for entering experimental data for base oil densities.

Water density submodel

There are three options available: Dodson & Standing, Kemp & Thomas and Sorelle.

Dodson & Standing (recommended): Dodson and Standing have published a correlation for compressibility and thermal expansion of pure water.


Kemp & Thomas: The Kemp and Thomas model is formulated for brines. The model compensates the change of compressibility and thermal expansion of brine due to variations in the ionic interaction with elevated pressures and temperatures. The brine content in the mud must be known if this model is selected. A sub-window appears when clicking the Brine button and the weight fractions of each salt can be specified. The weight fractions are relative to the whole fluid.

Figure 2-24: Brine data.

Brine data is only relevant if the Kemp & Thomas model is selected as water density model.

Sorelle (water): Sorelle et. al. also formulated a correlation for the water phase. The correlation is based on literature data.

Thermophysical properties

The thermophysical properties of the drilling fluid can be edited/viewed by clicking the Thermophysical properties button.

The data in this sheet is used in the dynamic temperature model.

All the parameters, Specific heat capacity, Thermal conductivity, Density and Static viscosity, can be given either as a constant value or as a temperature dependent value. Default values are displayed to the left. These values are automatically calculated based on entered component densities. Values can be customized by enabling the checkbox next to a field.


Figure 2-25: Thermophysical properties of drilling fluid.

Rheology

The Rheology model dropdown list is used to specify which correlation should be used for calculation of rheology data at elevated pressure and temperature. Three models are available; Power law, Bingham and Robertson-Stiff model. Robertson-Stiff is the recommended model for most situations.

It is possible to enter pressure and temperature dependent rheology data or the rheology curve can be given for only one pressure and temperature value.

The data are entered in the shear rate vs. shear stress (Fann reading) table for selected combinations of pressure and temperature. The rheology table is a spreadsheet table and it is possible to use copy and paste between other programs and Drillbench.

If Robertson-Stiff is chosen as rheology model, where applicable, the table should contain at least three Fann readings.

For Newtonian fluids, the check box must be enabled before the viscosity can be entered. The pressure loss computations for Newtonian fluids are equal for the Power law, Bingham and Robertson Stiff models. However, the ordinary variant uses built in models for pressure and temperature dependency, the extension HPHT gives the same viscosity at all pressures and temperatures.

Note: The Newtonian viscosity will overwrite the Fann readings in the tables. So if the user wants to switch between a Newtonian and a non-Newtonian model, two different fluids should be defined.


Figure 2-26: Rheology input.

Figure 2-27: Fann tables.


2.3.8 Temperature

Figure 2-28: Temperature input window.

Wellbore

Dynamic temperature model/Static table

In the Wellbore section, select whether the dynamic temperature model should be used or not. Since Hydraulics is a steady state model, a steady state temperature is calculated using the dynamic model.

The simplest case will be to use Static table. In this case a temperature profile is specified for the mud inside drill pipe and annulus. Pairs of measured depth and temperatures are entered both in the drill string and in the annulus. The number of pairs may be different for annulus and drill string. The program will interpolate between the entered points to get the information needed for the calculations. The first data points in the tables are the mud temperature at surface.

If you select one of the Dynamic temperature model options, a steady state heat transfer and temperature will be computed with grid cells generated both in the radial direction and along the flow line.

Depth reference

In the Depth reference section, you select to use either Measured depth or True vertical depth.


Note the following if you switch between the two measured depths:

• When you change from measured depth to true vertical depth and there are horizontal sections in the well, you can get duplicate depths in the table. These are removed when you leave the page. Information text about this is displayed. Reselect MD to avoid losing the data points.

• If you enter an inclination in excess of 90 degrees in the Survey window, you may lose data points. A warning is displayed.

Note: The simulation results are always displayed in MD.

Rig

In the Rig section, select the model for the injection temperature. The data specifies how to calculate the surface temperature of the drilling fluid just before being pumped into the drill string.

If Constant mud injection temperature is selected, the temperature of the mud pumped into the well will be the same throughout the simulation.

If Constant temperature difference is selected, the mud injection temperature will always be the given number of degrees below the mud outlet temperature, which is continuously being calculated, and will thus vary with time.

The third option is Surface temperature model. The user has to specify initial pit tank temperature and the total volume of the pit tanks that the mud passes through from the outlet back to the pumps.

2.4 Expert Input Parameters

The expert input parameters have been divided into four main groups.

Model parameters Number of grid points

Eccentricity Eccentricity of the drill string

Surface pipeline Pressure loss in surface equipment

RCH and choke Specifications for RCH and choke


2.4.1 Model parameters

Figure 2-29: Model parameters window.

Number of Grid cells

In this tab sheet the user specifies the number of grid cells used to create the underlying mathematical model. Increasing the number of grid cells will increase the accuracy of the simulation, but at the cost of the computation time. The computation time will at best increase linearly with respect to the grid cells. To avoid the simulation from becoming too time-consuming it is recommended to set this parameter around 50. Maximum number of cells is 2000.


2.4.2 Eccentricity

Figure 2-30: Eccentricity window.

If “maximum eccentricity in deviated sections” is selected from the drop-down menu, the program will use maximum eccentricity above a given deviation, concentric drill string in vertical section, and smooth transition in between. Tool joints are taken into account if used (see the “String” window).

Eccentricity of the drill string versus depth can be entered in this sheet. The default value is 0, i.e. drill string is taken to be concentric if the table is empty. Each line gives eccentricity from the specified depth and downwards. Eccentricity is zero above the first depth.

The sum of standoff and eccentricity is by definition always 100 %.

2.4.3 Surface pipeline

If there is a considerable loss of pressure in the surface piping between the pump and the wellhead, the surface pressure loss should be entered in this window. A linear interpolation will be used between the reading points, and a graphical verification of the surface pressure loss is plotted. The simulator assumes a linear interpolation from no pressure loss at zero flow rate up to the lowest flow rate entry, and a constant pressure loss at all rates above the maximum flow rate entry.


Figure 2-31: Surface pipeline window.

Note: The flow rate table must be given in increasing order.


2.4.4 RCH and choke

Figure 2-32: RCH and choke window.

Choke

If you are using a rotating control head (RCH), enable it in this window and specify information for the choke. The inner diameter of the choke must be given. The simulator automatically adds a surface pipe length to the system.

The user may control the well pressure in a dynamic simulation by modifying the well head pressure. In the choke input window the user specifies how to operate the choke by selecting either Pressure, Opening or Automatic from the Choke control drop down list. If Automatic choke control is selected, you also have to specify a constant bottomhole ECD.

Separator

A separator working pressure has to be set if “Use RCH” is enabled.


3. CALCULATION AND OUTPUT A variety of calculations can be performed with Hydraulics. Like the input window, the calculation window is divided into two: a navigation menu bar to the left and data entry with graphical display of the calculated results to the right, see Figure 3-2:.

The user chooses a type of calculation by selecting one of the Calculation navigators on the left side of Figure 3-2:. The calculation navigators are summarized below:

Hydraulics Determine hydraulic behavior during drilling

Surge & swab Calculate the tripping limitations

Sensitivity analysis Vary one parameter sequentially to study its sensitivity

Bit optimization Optimize bit nozzle size (TFA)

Volumetric displacement Calculate fluid front position and total volume pumped

All calculations are displayed in plots. All plots can be edited by pressing the right mouse button in the plot and selecting Properties. To print the plot or change its appearance, use the plot properties dialog, shown in the Figure below.

Figure 3-1: The plot properties dialog.

3.1.1 Hydraulics

The Hydraulics calculation window is shown in Figure 3-2:. Before performing calculations, some operational parameters must be entered.

The cuttings transport model has two options: No slip and Slip. If No slip is chosen, the cuttings are transported at the same velocity as the drilling mud (i.e. perfect hole cleaning). If Slip is chosen, the cuttings diameter and either minimum relative cuttings velocity or maximum cuttings concentration must be provided, and Hydraulics will compute the minimum velocity needed to transport the cuttings out of


the well. For section with inclinations of 30 deg or more the Zhou model [4] is used to predict the critical flow rate for hole cleaning. The Zhou model is show as separate curve along with the Moore correlation model.

Figure 3-2: Simulation - Hydraulics.

The results from the calculations are shown in plots of the following parameters, all plotted versus depth:

• ECD (Equivalent circulation density) • Pressure • Temperature • Equivalent viscosity • Velocity • Cuttings (velocity/transport ratio) • Critical flow rate (hole cleaning, Moore and Zhou model)

The casing shoe position is indicated on all plots by a dashed line.

3.1.2 Surge & swab

The surge & swab calculations are used to calculate the tripping limitations. It includes three calculation modes: fixed pipe velocity, maximum surge velocity, and maximum swab velocity. The results from the computations are shown in plots of the following parameters, all plotted versus bit depth:

• Maximum string velocity • Return flow rate • Pressure


• ECD (Equivalent circulation density)

The fixed pipe velocity mode is used to compute the well pressures at a known tripping rate. The maximum surge/swab velocity modes are used to find the maximum tripping speed that can be used without exceeding the pore- and fracture pressure limitations.

Not all of the control parameters are needed in the various modes. The currently superfluous parameters are disabled accordingly. Pump rate is used only if pump connected is chosen in the top status entry. Drill string velocity is used only if fixed pipe velocity is chosen as calculation mode. Safety margin is used only if max surge/swab velocity is chosen as calculation mode.

Figure 3-3: Calculation - Surge & swab, calculate tripping limitations.

The safety margin defines how close to the pore pressure the well pressure is allowed to decrease during swab, or how close to the fracture pressure the well pressure is allowed to rise during surge. The factor refers to no surge swab pressure - for swabbing, the pressure at TD is used as reference and for surge, the pressure at the shoe is used as reference.

Example: We wish to compute the pressure while swabbing from 2000m MD to 1000m MD with safety margin 0.25. The pore pressure at TD is 350 bar, while the static well pressure at TD is 390 bar, giving a pressure difference of 40 bar. In this case, Hydraulics will compute the tripping velocity that gives 350+(40x0.25) =360 bar well pressure at TD.


If the lowermost drill string end is closed, choose Float in the float status entry. If it is open, clear the Use Float valve option.

In the case of swabbing, calculations start with the bit at lower bit depth. The bit is moved upwards in steps according to the entry in number of steps, ending at the upper bit depth. One steady state computation is performed at each bit depth. Upper and lower bit depths are both included in the number of steps. For surge the computations are similar, with the upper bit depth as the starting point. Maximum string velocity and return flow rate is plotted vs. bit depth. Pressure in annulus and ECD is plotted vs. well depth. The bit is assumed to be positioned at the lowermost depth.

Note: The pipe velocity is defined as positive into the well and negative out of the well, hence:

• Surge positive velocity • Swab negative velocity

3.1.3 Sensitivity analysis

In Sensitivity analysis, several hydraulic computations are performed with one input parameter automatically altered between each computation. The Sensitivity analysis window is shown in

Figure 3-4: Calculation - Surge & swab, calculate tripping limitations.

The results are available in the following plots:


• ECD (Equivalent circulation density) • Pressure, • Equivalent viscosity, • Velocity • ECD at casing shoe and bottom hole, and • Pressure at casing shoe and bottom hole

Before the computations are performed, you must choose the varying parameter. The selection is performed from the drop-down menu in the X-axis parameter entry. In addition to the parameter interval between each computation, an upper and lower boundary must be entered.

Figure 3-5: Calculation – Sensitivity analysis.

The following input parameters are available as varying parameter (X):

• Pump rate • Rotation velocity • Density • Plastic viscosity • Yield point

3.1.4 Bit optimization

The Bit optimization module is used to find optimal bit nozzle size (TFA) and pump rate as function of bit depth. The Bit optimization window is shown in Figure. The results are available in the following plots:


• Optimal bit area, and • Optimal pump rate

Figure 3-6: Calculation – Bit optimization.

It is assumed that the drilling is most efficient at the optimal flow area and flow rate. Optimal bit nozzle size and flow rate are plotted versus bit depth. There are two ways of optimizing these parameters. You can either optimize by calculating the maximum bit hydraulic horsepower, or by calculating the maximum jet impact force. The jet impact force will be within 90% of its maximum when bit power is at its maximum, and vice versa. Thus the difference between these two models is marginal.

To find the optimal bit nozzle area and pump rate, the maximum pump pressure and pump power outlet must be provided.

One steady state computation is performed at each bit depth according to upper/lower bit depth and number of depths (including the boundaries). Remember that the higher the numbers of depths, the longer the computations take.

3.1.5 Volumetric displacement

The volumetric displacement module is used to determine the fluid front positions in the well and the total pumped volume during a sequence of fluid flow, see Figure 3-6. The fluids that are to be pumped are chosen from the drop down menus in the


first column in the table. If the fluids are not available the database must be updated using Drillbench (see Appendix B).

Figure 3-7: Calculation – Volumetric displacement.

Enter the pump rate and the volume of each fluid. The time period in the fourth column is computed automatically. The density in the fifth column is loaded from the database and may be altered by the user.

Start the sequence of fluid flow by pressing the Start button. The simulation can be paused at any time.

Fluid front positions and pumped volume are plotted vs. time. The fluid in the first line of the table is assumed to fill the well at simulation start-up. Thus this fluid will not appear in the fluid front plot.


4. MENUS AND TOOLBARS Menus and toolbar icons have standard Windows functionality. We assume that Hydraulics users are familiar with Windows operations, and will only describe the menu and toolbar functions specially designed for Hydraulics.

4.1 File

4.1.1 New

Use New in the File menu to create an input file from scratch. This dialog offers choices of starting with a blank file or with predefined templates. The template path is configured in the option dialog.

Figure 4-1: New file dialog.

4.1.2 Import

Use Import to import a survey file on ASCII format, a Petrel well path or Techlog LAS pore and fracture pressure. When selecting the appropriate survey data file the survey data import dialog appears. Select the appropriate column delimiter, the units used in the survey file and the number of header/footer lines to be skipped.


Figure 4-2: Survey data input from a text file.

The survey file must be in ASCII format with columns for measured depth, inclination and azimuth. By default, the program assumes measured depth in the first column, inclination in the second column and azimuth in the third column. If this is not the case, the column headers can be rearranged by drag and drop: Press the left mouse button on the column header, drag to the correct position and release the mouse button.

4.1.3 Export

Use Export to save the survey data in text file format.

4.2 View

Used to switch between Input and Calculation on the Navigation bar, see Figure 4-3. The navigation bar and log view can be displayed and hidden by checking their tag in the menu.


Figure 4-3: Switching between Input and Calculation navigators by the menu bar.

4.2.1 Well schematic

A schematic plot that includes the riser, seabed, casing/liner program, open hole and the drill string is shown by selecting View Well schematic or by toggling the well schematic button in tool bar. A visual inspection of the well can reveal errors in the input data. The well schematic has a properties window to toggle items and labels to be drawn, which can be opened if you right-click in the well schematic and select Properties.

Figure 4-4: Well schematic view.

4.2.2 Survey plot

To view a three-dimensional representation of the survey, select View Survey plot. The default view is in front of the XY-plane. To rotate the view around the well, move the mouse in the direction of desired rotation while pressing the left mouse button. To zoom in, move the mouse up while pressing the right mouse button. To zoom out, move the mouse down while pressing the right mouse button. To move the figure, move the mouse while pressing the left mouse button and the shift key. There is a menu line in the survey plot with a File and a View menu. To reset the view, select View Reset camera from the plot’s menu line. The plot can be saved in a variety of formats by selecting File Export… from the plot’s menu line.


Figure 4-5: 3D-survey plot view.

4.2.3 Log view

By default, the log view is located in the lower part of the main window. It displays errors, warnings and information messages concerning input data and calculations. Use the check box on the View Log View menu to display or hide the log. Double-clicking an error or warning leads the user to the input page that caused the problem. Clicking the right mouse button over the log displays a menu offering the following commands:

Clear messages

This command empties the log.

Save messages

This command lets you save the log contents to a text file for later review.

Show timestamp


This check box toggles the use of timestamps for the lines in the log. This feature can be used to distinguish messages from various runs and can be helpful when the content of the log is saved to a file.

4.2.4 Navigation bar

Toggle the navigation bar on/off. Hiding the navigation bar can be useful to make more room for the main input or simulation window. The state of this selection is saved between sessions.

4.2.5 Input

Switch to an Input window.

4.2.6 Expert input

Switch to an Expert input window.

4.2.7 Simulation

Switch to a Simulation window.

4.3 Tools

In the Tools menu, the user can access an input and output reports. The Tools menu is also where the user provides various paths to databases and defines measurement unit preferences.

4.3.1 Take snapshot

The snapshot feature places a snapshot of the active plot window on the Clipboard, which can then be pasted into reports or presentations. Combined with customized plot layouts this is a very useful tool for presentation of simulation results.

4.3.2 Report

4.3.2.1 Input report

The input report contains all input information within an easy-to-read and useful report. It is listed on the Tools menu on the main bar in Hydraulics; see Figure 4-6.


Figure 4-6: The Tools menu – Input report.

The report is in HTML format and uses standard HTML style sheets (CSS) to define the visual layout. This makes it easy to customize the format (fonts, colors etc.). Hydraulics provides a default style sheet (ircss.css) which can be edited or replaced to match the user preferred report style. Figure 4-7 shows the layout used in Hydraulics.

Figure 4-7: Layout of the Input report.

The format of the report makes it easy to export data to other applications as Microsoft Excel etc. The file can be opened by Excel directly, or the tables can be copied from the input report to an Excel-sheet by standard copy and paste.

However, if you are using Internet Explorer to view the input report, a far simpler way is included in this version. The data can be exported directly to an Excel sheet by a right-click on the table and then select Export to Microsoft Excel, see Figure 4-8. Then an Excel-sheet is opened containing the data in the selected table from the input report.


Figure 4-8: Export of Survey data from the input report to Excel.

4.3.2.2 Current results

The current results report includes a summary of the key information for the case and a copy of all the available plots.


Figure 4-9: Current results report.


4.3.2.3 Hydraulics system report

Hydraulics also has a system report as shown in Figure 4-11. The system report list the operational data and then hydraulic parameters as velocity, Reynolds number, Flow regime, ECD and pressure loss in each section. It also includes summary pressure losses over typical parts of the well, pump pressure and ECD at important positions.

Figure 4-10: Hydraulics system report.

4.3.3 Validate parameters

This command validates the input data and reports errors and warnings in the log view. If the message relates to an input parameter, double click the message to access the page in question. It can be started either by pressing:

on the toolbar or by selecting Tools Validate parameters from the menu bar.


4.3.4 Edit unit settings

To edit the unit setting, you can select Tools Edit unit setting from the menu bar, or click on the unit name in the status bar to pop up the unit menu.

Figure 4-11: Unit menu.

The unit menu is allows quick change of unit sets and access to the unit edit page.

4.3.5 Options

To open the options tab window, you can select it from the menu bar or by clicking on on the toolbar.

This is a dialog that controls the Drillbench program settings. This window is divided in 3 sheets: General, Appearance and Unit definitions, which are described below.


4.3.5.1 General

Figure 4-12: Location of the databases used in Hydraulics.

Library path

Fluids, casings and string components are selected from a library. The location of the library file is entered in this field. The library selected here is shared among all Drillbench applications. Use the arrow in the right corner of the field to select from a list of previous paths.

Template path

Path to Drillbench default template files.

At program startup

Reload last used file resumes the session you were working on when exiting Presmod the last time.

Remember last selected page


Start at the page you were on when exiting Hydraulic the last time.

View

Option to control if log window should open automatically when new messages are produced by Drillbench. Default is to automatically open log.

Input file

Show input read diagnostics

This is an option to enable diagnostic messages when loading an input file. This should normally not be used. It is only to be used when having trouble loading an input file. You may be asked by Drillbench support to turn this option on.

4.3.5.2 Appearance

Allow the user to modify color theme, icon style and tab layout according to personal preference.

Figure 4-13: Hydraulics mud window with different color settings.

4.3.5.3 Unit definitions

The unit settings can be changed by selecting the Unit definitions tab found under Tools Options in the menu bar, see Figure 4-15. Each unit is defined separately and saved in a specified unit file. However, predefined sets of units can be selected from the drop down menu. By default, SI units, metric (European) units and field


units are available. You can create your own set of units by selecting the preferred units and save to file with a new name.

Figure 4-14: Definition of units.

4.3.6 Export of charts

Charts can be exported as Vector Markup Language (VML) files. VML is an application of Extensible Markup Language (XML) 1.0 which defines a format for the encoding of vector information together with additional markup to describe how that information may be displayed and edited.

Right click on the chart of interest, and select Export as shown in Figure 4-17


Figure 4-15: Export-command by right-click on the chart.

When selecting Export, the window Figure 4-17 in Here you can select in which format the figure should be saved. Save the chart with an appropriate name.

Figure 4-16: Export-command by right-click on the chart.


4.3.7 Help

To open the Help window in Hydraulics you can select it from Help Help topics or you can open it by pressing F1.

The Help window will give you a short description and explanation of all the different windows in Hydraulics.

When pressing F1 from an input window, the help page for the current window will be displayed.

4.3.8 About

The Help About option gives you information about Hydraulics version number and the expiry date of the current license.

Figure 4-17: The About window in Hydraulics.


5. Appendix: Technical documentation

Hydraulics is an advanced steady state hydraulics calculator, which uses very complex models to obtain accurate and reliable results. It is a standalone application from the software Presmod under the Drillbench® software suite [1].

Hydraulics has a number of features in addition to those found in the steady state part of Presmod. These are summarized below, and this section further describes the new features utilized in Hydraulics, that are not present in Presmod.

• Automatic bit optimization, i.e. find maximum bit hydraulic power or jet impact force when pump pressure is fixed and pump power is restricted to be below a maximum value.

• Calculate cutting slip and its effect on bottom whole pressure.

• Sensitivity analysis versus a number of different parameters.

• Automatic adjustment of rheology when both laboratory and field data are available.

• Repeat automatically bit optimization and surge/swab calculations for a number of different bit depths within a specified range.

• Include contribution to surge and swab pressures from acceleration of drilling fluid.

5.1 Hydraulics

A complex and accurate fluid description can be given in the Drillbench database. Drillbench must be used to enter or modify the database, but data can be imported into Hydraulics directly from the database.

Database descriptions of fluids must be modified to match Hydraulics input. With the procedure given below, information from the database on pressure and temperature dependence of density and rheology are fully exploited, also when Hydraulics input data does not match database data.

ROP will be taken into account through modified density and annular flow rates.

5.1.1 Adjustment of density

Use the algorithm that is used for altering inlet density during a dynamic simulation, and fill the well with the modified fluid.

5.1.2 Adjustment of rheology

Plastic viscosity pµ and yield point yτ are calculated using FANN readings at the two highest shear rates, which are normally at FANN rotation rates 300 and 600 RPM. A standard FANN viscometer is tuned such that


300600 θθµ −=p B1

PY µθτ −= 300 B2

where plastic viscosity is in cP and yield in lbm/100ft2. Note that elsewhere in this document, SI units are used throughout.

In Hydraulics, fluid rheology can be defined in several ways:

1. Rheology data at many different pressures and temperatures can be entered in the Drillbench database. Drillbench is required to enter or modify data, but fluid data can be imported into Hydraulics directly from the database without starting Drillbench.

2. pµ , yτ , and a 3.0 RPM Fann reading at standard conditions can be specified under “Basic input - Mud” in Hydraulics, having the Rheology panel’s button set to PV, YP, low Fann.

3. FANN data at standard conditions can be entered under “Input - Drilling fluid” in Hydraulics.

4. pµ and yτ in each of the Simulation window.

The following rules are used to combine the different kinds of input data:

1. pµ and yτ specified in the current calculation windows, overrides pµ and yτ data under “Basic input - Mud”.

2. If specified pµ and yτ does not match database rheology data at lowest pressure and temperature, database rheology data at lowest pressure and temperature are modified to match specified pµ and yτ , and database rheology data at other pressures and temperatures are modified accordingly.

3. If pµ , yτ and 3.0 RPM reading are specified under “Basic input - Mud”, database rheology data at the lowest pressure and temperature are replaced by data at 600, 300 RPM that corresponds to the specified pµ and yτ , in addition to the specified 3 RPM reading. Modifications under point 2 are always carried out before point 3.

4. If rheology data at standard conditions are specified under “Input - Drilling fluid”, database rheology data are first modified to match pµ and yτ (see point 2), then database data at the lowest pressure and temperature are replaced by the rheology data given under “Input - Drilling fluid”.

An advantage of scaling rheology data rather than making calculations with the Bingham model when pµ and yτ are specified is that deviations from the Bingham model in the rheology data are maintained. Data is just scaled such that best fit values of Bingham parameters get the desired values. Another advantage is that results with unmodified rheology are maintained if the changed pµ and yτ are the same as the best fit values at standard conditions.


5.1.3 Input and output

For input flow rates, RPM, ROP, density, pµ , yτ , 3.0 RPM Fann reading, etc., Hydraulics can plot a number of interesting parameters versus the fixed depth and down to the bit depth.

5.2 Hole cleaning

The following theory is based on Section 4.16 “Particle slip velocity” in Ref. [2]

Define particle Reynolds number by

a

sslf dvN

µρ

=Re B3

and friction factor by

KAEFf = B4

here F is viscous drag force, A is characteristic area, and KE is kinetic energy per unit volume, given by

221

slfK vE ρ= B5

For calculation of terminal velocity, set

( ) sfsbo gVFWF ρρ −=−= B6

where W is particle weight, boF is buoyant force, and sV is particle volume. If A for a perfect sphere is used,

−=

f

fsssl f

dgvρρρ

34

B7

For Reynolds numbers below 0.1, the Stokes law give acceptable accuracy. Stokes law is obtained by using

Re

24N

f = B8

Expressions for apparent viscosity and friction factor are given by correlations. Ref. [2] gives three commonly used correlations, and find that the Moore correlation is the one that matches published data best.

5.2.1 Moore correlation

Formula 4.107 in Ref. [2] (see also Ref. [3]) reads


nn

n

a vddK

+

−

=−

0208.02

144

1112µ B9

where v is average fluid velocity. In consistent units the formula is:

nn

a nn

ddvK

+

−

=−

31212

1

12

µ B10

An alternative expression is given by Reed and Pilehvari, and is equivalent to the above formula with the power of the rightmost factor reduced from n to n-1:

18

−

=

n

effa D

vKµ B11

with

( )12

332

+−=

nnDDD ioeff B12

According to Moore correlation, friction factor is essentially constant at approximately 1.5 for Reynolds numbers above 300.

≥

<<

≤

=

2Re,Re

2Re,Re1Re,Re

1Re,ReRe

,5.1

,22

,40

NN

NNNN

NNN

f B13

Ref. [2] uses 300 and 3 2Re,1Re, == NN , which can be modified to avoid

discontinuities without altering the friction factor very much. Accordingly we will use

3058.32040 2

1Re, ≈

=N B14

and

11.2155.1

22 2

2Re, ≈

=N B15

Reynolds vs. friction factor with the new transition Reynolds numbers is plotted in Figure 5-1.


Figure 5-1: Particle friction factor vs. Reynolds number according to the Moore correlation.

From this basis the particle Reynolds number, slip velocity, and friction factor can be calculated. Friction factor and particle Reynolds number can be eliminated to obtain an explicit formula for slv within each of the three flow regimes. The expressions are

( )

( )

≥−

<<

−

≤−

=

2Re,Re

2Re,Re1Re,

31

2232

1Re,Re

2

98

,332

,301

NNgd

NNNdg

NNgd

v

f

fss

sfa

fs

a

fss

sl

ρρρ

ρµρρ

µρρ

B16

The following calculation procedure is used:

a) Calculate slv and ReN assuming transitional regime ( 2Re,Re1Re, NNN << ), and determine flow regime.

b) If 1Re,Re NN < or 2Re,Re NN > , redo calculation of slv and ReN using the corresponding expression in Eq. 3.13.

It can be shown mathematically that the Reynolds number calculated under b) is consistent with the flow regime determined under a).

10-1

100

101

102

103

100

101

102

103

Particle Reynolds number

Fric

tion

fact

or

Friction factor, Moore correlation

f NRe,1NRe,2


5.2.2 Zhou model: Horizontal and inclined wellbore

For section with inclinations of 30 deg or more the Zhou model [4] is used to predict the critical flow rate for hole cleaning. The model prediction versus available experimental reports has been compared and showed good agreement.

• The volume of cuttings accumulated in the annulus is very sensitive to the liquid flow rate;

• Injection of gas has positive effect on high viscosity fluid and the effect is less when the fluid has lower viscosity.

• High gas-liquid ratio has positive effects on cuttings transport for a given liquid flow rate;

• Increase of hole angle (from vertical) results in great increase of required mud velocity; 60 to 0 deg from vertical is the most difficult angle to clean;

• Small size cutting are easier to be transported with high viscosity fluid compare to lager cuttings; and it becomes much more difficult with sizes down to 0.5mm;

• Increased mud weight will help hole cleaning;

• The effect of pressure on cuttings concentration is related to gas in-situ volume, high pressure will cause a decrease in cuttings transport.


Figure 5-2: Hydraulics – Critical flow rate.


A new input parameter is particle size, sd . Cuttings density can be taken from input to the temperature model.

Possible output parameters are slip velocity, cuttings transport ratio, volume fraction of cuttings. These may be plotted versus depth with bit depth fixed. Alternatively, worst values along the annulus may be plotted versus bit depth. Results may also be applied for other hydraulic calculations.

Cuttings transport ratio is defined by

vv

vvF slT

T −== 1 B17

which is unity if cuttings move with same average velocity as mud, and zero if cuttings do not move relative to the well. Volume fraction of cuttings is

mTs

ss qFq

qf+

= B18


where sq and mq are volume flow rate of cuttings and mud. Assuming cuttings size is larger than size of individual grains, cuttings rate is

dtdDAb B19

where bA is area cut by the bit.

Suggested definition of acceptable cuttings transport: 1.0>TF

5.3 Surge and swab

New features relative to Presmod surge and swab are:

• A loop over bit depths in a given range. New grid is generated for each bit depth.

• Acceleration pressure. Acceleration pressure will be calculated assuming incompressible fluids (an advanced dynamic simulation would be required to take compression properly into account), and added to frictional effects.


Two options:

1. Maximum string velocity (surge or swab) as a function of bit depth (within a given range), with pressure staying inside the pore-fracture pressure window. Expected to be relatively time consuming.

2. Pressure at bit as a function of bit depth using specified drill string velocity.

Mud column below bit only contributes to dynamic effects, which are not taken into account.

5.4 Sensitivity

Parameters like density, plastic viscosity ( pµ ), yield stress ( yτ ), flow rate and rotational rate, can be used for sensitivity studies.


The sensitivity analysis will produce plots of pressure and ECD at bottom, casing shoe, and observation points versus flow rate, RPM, density, pµ , and yτ . Bit depth is fixed.

5.4.2 Bit optimization

The following theory is based on Section 4.13 “Jet Bit Nozzle Size Selection” in Ref. [2].

Most commonly used hydraulic design parameters are


• nozzle velocity

• bit hydraulic horsepower

• jet impact force

Pump pressure, which must be kept at or below its maximum value, can be written as

dbp ppp ∆+∆= B20

where the first right hand side term is bit pressure loss and the second is the sum of all other pressure effects including frictional pressure loss, pressure loss across area changes, acceleration effects, and u-tube effects. The contribution from turbulent frictional pressure loss inside the drill string is normally dominant. The following simplified model is used below to demonstrate important effects:

md cqp =∆ B21

where c and m are constants with m typically close to 1.75. With realistic drilling fluids, c and m are not constants, but depend on pressure, temperature, and shear rate. Shear rate depends on both flow rate and diameters.

Using the simplified model, Ref. [2] states that when hydraulic horsepower is at its maximum, bit hydraulic horsepower will be within 90% of its maximum and vice versa.

5.4.3 Maximum bit nozzle velocity

Pressure loss across bit is

2

2

d

nb C

vp ρ=∆ B22

which can be inverted to get bit velocity as

ρb

dnpCv ∆

= B23

If mud density is fixed, bit pressure loss must be increased as much as possible to obtain maximum velocity. This is obtained by reducing mud flow rate to the minimum rate that ensures good hole cleaning, and then reduce nozzle diameters as far as possible without exceeding pump pressure.

Hence, maximum nozzle velocity without exceeding maximum pump pressure is obtained when flow rate is at a minimum.

5.4.4 Maximum bit hydraulic power

Bit hydraulic power is given by

qpP bHb ∆= B24


Also here, bit pressure loss bp∆ can be increased by reducing flow rate and decreasing nozzle diameters as far as possible without exceeding maximum pump pressure. More detailed hydraulic calculations are required to determine whether the product of bit pressure loss and flow rate increases or decreases as flow rate increases. Bit hydraulic power will always have a maximum at some flow rate since it tends to zero when flow rate approaches zero (bit pressure loss cannot exceed maximum pump pressure plus u-tube effects), and it tends to zero as flow rate is increased towards the rate where pd pp =∆ .

The maximum bit hydraulic power is obtained by maximizing the right hand side of

( )qppqpP dpbHb ∆−=∆= B25

with pp fixed at its maximum pump pressure.

By simplification,

1+=∆

mp

p pd B26

is obtained by setting the derivative of HbP with respect to q equal to zero. With m=1.75, the simplified model predicts that maximum bit hydraulic power is obtained when bit pressure loss is 63.6 % of pump pressure.

For a more general result, hydraulic power is represented by the function

)(qqfPHb = B27

which gives

0)()( =′+= qfqqfdq

dPHb B28

5.4.5 Maximum jet impact force

Jet impact force is given by

( ) ( ) bdnj pqCvqvt

mt

mvF ∆==∆

∆

=∆

∆= ρρ B29

It can be shown that the bit Reynolds number

a

nnbit

dvRe

µρ

= B30

where the index n refers to nozzles and is maximized when jet impact force is maximized. Some experiments find that penetration rate is proportional to bit Reynolds number raised to a constant power.

The simplified model for dp∆ predicts maximum jet impact force when


22+

=∆m

pp p

d B31

With m=1.75, the simplified model predicts that maximum jet impact force is obtained when bit pressure loss is 46.7 % of pump pressure.

5.4.6 Optimization with Hydraulics

Use built in pressure models to optimize bit hydraulic power or jet impact force with the following constraints:

(1) Pump pressure below maximum

(2) Stay at flow rates low enough to allow pumping at maximum pump pressure without exceeding maximum pump power outlet.

(3) Flow rate high enough to ensure satisfactory cuttings transport.

This procedure has advantages over the formalism used in Ref. [2]:

• Frictional pressure loss and pressure losses across area changes are calculated using pressure and temperature dependent rheology and density, with a three-parameter rheology model. The parameter m, which is constant in Ref. [2], becomes a function of pressure, temperature, and shear rate.

• Differences in hydrostatic pressure inside and outside drill string are taken into account.


New input parameters are:

• maximum pump pressure,

• pump power outlet,

• parameter selection (maximum bit hydraulic horsepower or maximum jet impact force).

Minimum flow rate for good cuttings transport can either be calculated, be an additional input parameter, or set to zero.

Possible output parameters are nozzle area, flow rate, and bit pressure loss, and pressure loss in the rest of the system with optimal nozzle area and flow rate. These may be reported at the bit depth specified in the input file, or plotted versus bit depth throughout the current open hole section. In the latter case, beginning and end of open hole section must be specified somehow (may also be used for e.g. surge swab calculations).


6. KEYBOARD SHORTCUTS

Alt+F open File menu Alt+E open Edit menu Alt+V open View menu Alt+T open Tools menu Alt+H open Help menu Ctrl+N New file Ctrl+O Open Ctrl+S Save Ctrl+C Copy Ctrl+X Cut Ctrl+V Paste Alt+BkSp Undo Ctrl+Ins Insert rows in a table Ctrl+Del Delete rows in a table F9 Start F8 Step Ctrl+F2 Reset Ctrl+F12 Take snapshot Ctrl+U Edit unit settings


7. ACKNOWLEDGEMENT Drillbench uses the following third-party tools:

• JEDI Visual Component Library (JVCL) JVCL portions are licensed from Project JEDI, and the source code can be obtained from http://jvcl.sourceforge.net/

• JEDI CODE LIBRARY (JCL) JCL portions are licensed from Project JEDI, and the source code can be obtained from http://homepages.borland.com/jedi/jcl/

• The Visualization ToolKit (VTK) VTK is copyright © 1993-2004 Ken Martin, Will Schroeder, Bill Lorensen All rights reserved. VTK is available from http://www.vtk.org/

• Nullsoft Scriptable Install System (NSIS) NSIS is copyright (C) 1999-2006 Nullsoft, Inc. and is available from http://nsis.sourceforge.net/

• TeeChart TeeChart is copyright © David Berneda 1995-2006. All Rights Reserved. http://www.steema.com/

• LiquidXML LiquidXML is copyright ©2006 Liquid Technologies Limited. All rights reserved. http://www.liquid-technologies.com/

• FLEXlm FLEXlm is copyright ©2002-2006 Macrovision Corporation. All rights reserved. http://www.macrovision.com/

• TMS Component Pack TMS Component Pack is copyright © 2001-2009 by tmssoftware.com. All rights reserved

http://jvcl.sourceforge.net/

http://homepages.borland.com/jedi/jcl/

http://www.vtk.org/

http://nsis.sourceforge.net/

http://www.steema.com/

http://www.liquid-technologies.com/

http://www.macrovision.com/


8. REFERENCES [1] Drillbench Presmod documentation.

[2] A. T. Bourgoyne Jr., K. K. Millheim, M. E. Chenevert, F. S. Young Jr.; "Applied Drilling Hydraulics", First printing, Society of Petroleum Engineers, 1986.

[3] P. L. Moore: "Drilling Practices Manual", The Petroleum Publishing Co., Tulsa, 1974.

[4] L. Zhou: “Hole Cleaning During UBD in Horizontal and Inclined Wellbore”, IADC/SPE Drilling Conference, Miami, 2006.

Documents

USER MANUAL 6 · 2016. 12. 8. · Drillbench Hydraulics User Guide Page ii 4.3.6 Export of charts 49 4.3.7 Help 51 4.3.8 About 51 5. Appendix: Technical documentation 52 5.1 Hydraulics