CasingSeat QuickGuide Manual

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CasingSeat Manual

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List of Figures

Figure 1 – CasingSeat User Interface ... 5

Figure 2 - Wizard Toolbar ... 5

Figure 3 - General Tab ... 6

Figure 4 - Casing and Hole Size Selector ... 7

Figure 5 - General Design Parameters ... 10

Figure 6 - Lithology Table ... 11

Figure 7 - Well Schematics ... 12

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Introduction

The CasingSeat software is a casing seat selection tool that provides rigorous shoe selection calculation routines to optimize shoe locations, based on pore pressure and fracture gradients, and user-defined design constraints.

The CasingSeat software delivers preliminary well design tools that support: Selection of casings and hole sizes

Setting depth for the casings

Determination of the highest allowable cement tops Creation and maintenance of mud schedules

The CasingSeat is fully integrated with the StressCheck software to provide a convenient path to detailed design and stress analysis of the well completion.

In this part of the project you will do: Data gathering and interpretation

Determination of shoe depths and number of strings (Mud-window) Selection of hole and casing sizes

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The CasingSeat User Interface

Menu Bar Toolbars Well Explorer Associated Data Viewer

Figure 1 – CasingSeat User Interface

CasingSeat Set-up

Using Wizard Toolbar

To navigate the Wizard, click the Next and Previous buttons to move through the dialog boxes

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This pull-down list has dialog boxes, spreadsheets, and plots listed that can be used to guide you through the data-entry phase of your analysis. Although you can use the menus and the visual cue of the grayed commands to determine what commands to select, the Wizard automatically provides the correct sequence and requires minimal steps from you to specify data successfully.

General

Well>General>Options tab to specify the Well depth and vertical section definition.

Note: when you are working on a Design which you have from COMPASS, it will be filled out automatically.

Figure 3 - General Tab

Wellpath Editor

Well>Wellpath Editor: Use the spreadsheet to define Wellbore trajectory for planar and

three-dimensional directional wells.

The CasingSeat software uses minimum curvature interpolation for all point-of-interest mapping of MD and TVD, except where MD-TVD data input format has been used. The software allows inclinations up to 89.99 degrees.

Note: when you are working on a Design which you have from COMPASS, it will be filled out and calculated automatically.

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7 Casing and Hole Size Selector

Well>Casing and Hole Size Editor: In the CasingSeat software, you can define Hole

and Casing sizes with a graphical tool or by manual input to a spreadsheet.

The Casing and Hole Size Selector displays alternating colored rows of hole and casing symbols. Holes are represented as circles and casings as squares.

Figure 4 - Casing and Hole Size Selector

Hole and Pipe Diameters

Hole and casing diameters are based on the following requirements:

Production – production equipment requirements, including tubing, subsurface safety valve, submersible safety pump and gas lift mandrel size; completion requirements (e.g.: gravel packing); and weighting the benefits of increased

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tubing performance of larger tubing against the higher costs of larger casing over the life of the well (economical aspect).

Evaluation – logging interpretation requirements and tool diameters

Drilling – minimum bit diameter for adequate directional control and drilling performance, available downhole equipment, rig specifications, and available BOP equipment.

The preceding requirements normally impact the final hole and casing diameter. As a result, casing sizes should be determined from the inside outward.

Allowable Hole Sizes Spreadsheet

To specify the hole sizes allowed below the casing OD for drill through operations. The hole sizes defined determine the bit sizes that can be used for drilling through that casing. Hole sizes are taken in combination with allowable casing sizes to determine viable well configuration (that is the total number of hole/casing combinations from surface to TD).

Note: hole sizes larger than the casing OD are allowed and represent under-reaming (Bohrlochvergrößerung) operations.

Allowable Casing Sizes Spreadsheet

Well>Allowable Casing ODs to specify the casing ODs allowed for the hole size. Each

casing specified must have an OD less than the hole size for that row.

Design parameters Theory

Mud Program

The most important mud program parameter used in casing design is the mud

weight. The complete mud program is determined from:

Pore pressure

Formation strength (fracture gradient and borehole stability) Casing shoe setting depths

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9 Lithology

Hole cleaning and cuttings transport capability

Potential formation damage, drilling rate, stability problems Formation evaluation requirements

Environmental and regulatory requirements

Shoe Depth Design Constraints

Shoe depth and the number of strings are determined historically by the mud weight and the fracture gradient. The following factors affect the shoe depth selection:

Regulatory requirements

Kick tolerance: if gas bearing layers are expected

Hole stability: function of mud weight, deviation and stress at the wellbore wall or it can be chemical nature

Differential sticking: the probability of occurrence increases with increasing differential pressure btw the wellbore and formation, increasing permeability the formation, and increasing fluid loss of the drilling fluid

Zonal isolation: by shallow fresh water sand, lost circulation zones Directional drilling concerns: a casing string is often run after an

angle-building section has been drilledavoids keyseating problems Uncertainity in predicted formation properties: for exploration wells

General

Well>Design Parameters>General tab to specify the following general parameters that

are used for calculating the casing design:

Method used to establish casing-setting depths (use Bottom-Up) Specific requirements for acceptable casing scheme solutions

Criteria used to rank casing scheme solutions in the results based on inputed costs. Note: when the casing cost is calculated, the cost of K-55 steel is used, and a wall thickness of ½” for all casing strings is assumed

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Design can be performed either individually or both simultaneously

Enter the setting depth of The first casing string

Select the min allowable OD of the last casing string

Figure 5 - General Design Parameters

Setting Depth

Well>Design Parameters>Setting Depth: To specify the vertical depths at which

additional (forced) setting of casing is required. You can specify:

For bottom-up design, a deeper setting depth for an interval in the well For top-down design, a shallower setting depth for an interval in the well

Lithology

Select Geology>Lithology spreadsheet to: Name each formation layer

Specify the type and depth for each layer

Define the value of the operating constrains selected from the Design Parameter dialog box (not part of the lecture)

Specify properties for each layer Note:

In the first row the Layer Top TVD has to be where the earth begins

Entering Yes to the Competent layer allows a casing to be set within that layer

Specify whether the completion is going to be cased or open hole

Select max acceptable OD for the first casing. This is the casing on which you plan to install BOP, thus allowing for kick control.

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Figure 6 - Lithology Table

Pore Pressure and Fracture Gradient

Select Geology>Pore Pressure spreadsheet to specify formation pressures or equivalent mud weight at specified depth.

Select Geology>Fracture Gradient spreadsheet to specify fracture pressures or equivalent mud weight at specified depth.

Note:

These data can be Copy-Pasted from Excel spreadsheet

It is enough to fill out either the pressure or the mud weight the other one will be automatically calculated by CasingSeat.

Geothermal Gradient

Select the Geology>Geothermal Gradient tab to specify basic formation temperature data. You will need to enter the surface temperature and one of the following two: either the Temperature at bottomhole (TVD) or the temperature gradient. When one field is changed, the other updates automatically.

Calculate

Open the Calculate Dialog box and specify pore pressure and fracture gradient margins to be included in the analysis. After that, perform the calculation.

Margins:

Use margins to model the pore pressure and/or fracture gradient as being smaller or larger than defined in the Geology>Lithology spreadsheet. Any non-zero margins have

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the effect of shifting the base case pore pressure and fracture gradient curves with the amount specified in these fields.

Note: Base case calculates with the given values, and if you make some changes it will update automatically. If you want to account for safeties in the mud window use lower margin (LM) calculation. It might change the amount of casing strings you need and the shoe setting depths can also be affected.

Analyzing Results

The following graphs, figures and diagrams are useful for interpreting results:

Final Well Configuration (especially it you have many solutions for casing design) Well Schematic to display the casing scheme as a well schematic

Figure 7 - Well Schematics

Design Plot: displays the casing scheme as a plot based on EMW vs depth (MD or TVD). This plot shows the pressure curves in association with the casing schematic.

Each casing string is considered as a full string. The

CasingSeat software does not consider the use of a liner. Calculations are generally focused on the integrity of the open hole.

TOCs are part of the result. The

CasingSeat software assumes a 16 ppg cement slurry and calculates the max height such that the formation will not fracture.

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Figure 8 - Design Plot (Lower Margin)

Casing Scheme: it is the summary of the selected casing in a table form.

Useful Features and Tipps

Using Tabs

Creating new tabs: Tools>Tabs. They are window tabs (like in Excel) and are really useful, because you can set them up at the beginning (also as a Template) and look at the different sections and result only with a mouse click.

Unit Converter

As in COMPASS we already discussed, there is a possibility to choose an already defined (SI,API) unit system or create your own unit system. If you need just one value somewhere to convert in another unit, you don’t need to change the whole unit system in the design. Just click on the value of interest and click on F4 button.

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Reference

CasingSeat; Release 5000.1.7 Training Manual. 2010 by Landmark Graphics Corporation