6.2 - Level 2: Operator
Operator represents a specific oil company or business unit and contains settings which will affect all levels and all fields and wells below it. The anti-collision rules for all wells under the operator are defined here.
The Operator Properties dialog will automatically open when a new operator is created. To access the Operator Properties for an existing operator, right click on it in the Object Explorer. The Operator Properties dialog has the following features:
6.2.1 - Company Properties
Name: This is the name of the operator and any change made here will be reflected in the Object Explorer.
Contact: A contact for the operator can be entered. This is for information purposes only.
Address: The address of the operator; this is for information purposes only.
Primary Logo: The logo is the default logo which can be displayed on reports. Click on the Select Logo button to choose an image from your device, or the Clear button to remove the selected image. Well Seeker X supports bmp, png and jpg formats. The logo file size must be less than 2 MB.
Secondary Logo: This is an additional Logo which can be added to plots and reports allowing the user to show their company logo as well as the clients.
Set Password: At every level in the database structure, the user has the option to lock the properties via a “Locked” checkbox at the bottom left of each dialog. When locked, the user is unable to edit any of the inputs at this level without the relevant password. This option opens the set password dialog, where the user can enter and where necessary change their chosen password.
Locked: This checkbox allows the user to lock all the editable cells in the dialog. If NO password has been entered in the set password section, then the user can freely select to lock and unlock the dialog. If a password has been added, then the user must enter the relevant password to both lock and unlock the dialog.
**Customer is a Directional Company:**The user can check this box to mark the operator as a directional company. This is just for reference and has no other function in the software.
6.2.2 - Anti-Collision Settings
The Anti-Collision Settings section allows the user to define the rules for generating ellipse of uncertainty and calculating anti-collision results for the operator. These rules will apply to all wells contained under the currently selected operator.
Scan Method: This is the anti-collision scan method used for all proximity scans. Well Seeker X currently supports three options:
3D Closest Approach: Finds the closest approach of the offset well in 3D space. To visually represent the scan, imagine an ever-expanding sphere with its origin at the point of interest on the reference well. The point on the offset well which first touches the sphere is the point of closest approach. A 3D scan will always find the point of closest approach regardless of which direction the offset well is coming from.
Travelling cylinder North / High side: The scan describes a circular plane perpendicular to the wellbore. To visualize, imagine a 2D disc with its origin at the point of interest on the reference well with its axis perpendicular to the well bore. The point at which the offset well intersects the disc is the point of closest approach. Travelling cylinder scans can miss or be very late to detect offset wells which approach near perpendicular to the reference. This scan should be used with caution or when backed up by an accompanying 3D closest approach scan. The difference between the North / High side scans is simply the reference angle used when determining the direction of the offset well. High side references the offset well to the high side of the current well bore, this can lead to confusing outputs as at low inclinations the high side of the wellbore can swing dramatically between survey points. North referenced travelling cylinder scans use North (True or Grid, whichever is selected at Field Level) as the reference where the high side angle is calculated and the current wellbore azimuth is added.
Horizontal Scan: Finds the point of closest approach of the offset well by scanning horizontally on the reference wells current TVD. This scanning method is rarely used as it can miss potential collisions.
Error Surface: This describes the error surface used to calculate separation or clearance factors in Well Seeker X. It currently supports three methods:
Circular Conic: Uses the ellipse semi major axis as the error radius regardless of which direction the wells are approaching from. This can lead to very pessimistic AC results.
Pedal Curve: This method describes the errors as an ellipse (elliptical conic); however, it uses the pedal radius in separation factor calculations. This is the radius of the ellipse perpendicular to the line of closest approach.
Combined Covariance: This method uses the same error radius as elliptical conic; however, the total error radius is calculated by root sum squaring (RSS) the two radii. This method should be used only with errors at 2.79 Sigma and above.
Ellipsoid Scalar Expansion: This method describes errors as a 3D ellipsoid. The reference and offset ellipsoids are then expanded using the same scale factor until they come into contact. The scale factor required to achieve this is the separation factor. Ellipsoids that are already touching before scalar expansion have a SF of 1. Ellipsoids that overlap before scalar expansion have a SF of <1. This method requires greater CPU power than the other methods.
Warning Type: This defines the type of warnings which Well Seeker X will flag on the anti-collision report and it has two settings:
Error Ratio: This is also known as “Clearance factor” or “Separation Factor”. It is calculated by dividing the centre to centre distance by the summed radius of the EOU. The error surface defines the total error radius. Well Seeker uses the Pedal Curve Method when calculating the reference and offset error radius values.
Rules Based: This allows the user to define an Anti-collision rule which can be either an Error ratio or a depth ratio. In the Type column the user can select from the following options:
Error ratio: This is just a normal separation factor-based rule and works in the same way as the Error Ratio option above. Note the user does not need to enter anything in the Max Radius cell for this rule.
Depth ratio: This option takes the current measured depth and multiplies it by the ratio. This value is then the C-C distance warning limit at that given depth. If the C-C distance at this depth is less than this value Well Seeker will flag this with a warning. The user can set the max radius to limit this; however, the user does not need to enter a maximum radius for the rule to work. For example, if the depth ratio was set at 0.1 at a measured depth of 100m, the rule would be a minimum C2C of 10m. Anything less than this would be flagged.
Min C-C Distance: This option lets the user select a radius, which acts as the C-C distance warning limit along the entire well and if you end up with a C-C distance less than the radius entered, you will get a warning. This differs from the above since the radius is fixed and does not change based on depth. Note the user does not need to enter anything in the Ratio cell for this rule.
It is possible to combine these AC rules. This allows the user to include multiple warnings when running the AC calculations. For example, the user could have the standard error ratio warnings selected at the same time as the minimum centre to centre. In the above, if the warnings on lines 1-4 were selected, this will flag the various levels for SF and also flag any point with a C-C of less than 5m/ft (whatever the selected units are)
The warning types are defined in the warning type grid and can be named however the user desires and there can be an unlimited number of rules which can be evaluated. The warning grid will change depending on whether rules based, or error ratio is selected.
Errors Evaluated @ Sigma: Sets the number of standard deviations used when calculating separation factor. Separation factor in anti-collision reports and the real time AC will be displayed to this sigma value. Default value is 2.
All other survey error outputs use the Errors Output @ Sigma setting below.
Errors output @ Sigma: Sets the number of standard deviations used for calculating all survey error outputs EXCEPT for separation factor. Ellipse semi-major and semi-minor values for error ellipse reports, anti-collision reports, real time AC and plots will be displayed to this sigma value. Default value is 2.
For separation factor calculations, the software uses the above Errors Evaluated @ Sigma setting.
Increasing the sigma value increases the size of error ellipses, but also increases the probability that the wellbore is inside the error ellipse. The below table represents the confidence levels for one, two- and three-dimensional Gaussian distribution with equal standard deviations in all directions.
When using the Pedal Curve method (as is used within Well Seeker), the probability of collision is effectively broken down into a one-dimensional problem, therefore at 1 sigma there is a 68% chance that the well path will reside inside the EOU and this increases to 95% at 2 sigma. This value also determines at what sigma level the error ellipse sizes are displayed on the error ellipse report. The below picture shows a visual representation of the pedal curve around an ellipse of uncertainty.
Casing: This option allows the user to decide if the casing radius is to be considered in the anti-collision calculation.
Include Casings: If “yes” is selected in the casing option, this option defines how the casing radius is used in the separation factor calculation.
If “Add” is selected, the radius is added to the error radius and survey bias.
If “subtract” is selected, the casing radius is subtracted from the centre to centre distance.
It should be noted for top hole sections where the centre to centre distances are small, this option can give a negative centre to centre distance.
Errors Calculated From: This option allows the user to define where the EOU calculation starts from. For land wells and jack-ups, “surface” is usually selected. However, for deep water wells, “mudline” is usually selected.
TC Plot Safety Factor: This option allows the user to apply a safety factor to the errors which are generated in the travelling cylinder plot. With a value of one entered here (default), the ellipses will generate as per normal i.e. no safety factor applied, which means touching the No-Go line on the plot effectively equates to a SF of 1. If the user enters a value of for example 1.2 here, the ellipses displayed on the TC plot will be 20% larger, 1.5 will be 50% larger etc, giving the safety factor required. Note: This value cannot be anything less than 1
Warnings Grid: This allows the user to define the warning rules which will be displayed on anti-collision reports. If “Error Ratio” is selected as the warning type, the grid will display “Name” and “Ratio” Columns. The name will be displayed on an anti-collision report if the separation factor is less than or equal to the value in the “Ratio” column. If “Rules Based” is selected as the warning type, the grid will have the additional columns “Type”, “Max Radius” and “Active”. The type column specifies if the value entered in the “Ratio” column is a clearance factor or a depth ratio. The “Max Radius” Column only applies to depth ratios and specifies the maximum radius to be added to the total error radius. The “Active” column specifies if the rule will be evaluated or not.
6.2.3 - WPTS Separation Rule
WPTS Separation Rule: Toggling on the Use WPTS Separation Ruleoption on instructs the software to use the WPTS Separation Rule to calculate the separation factor value when running anti-collision. It also allows the user to set the value for the two additional parameters used in the calculation – the surface margin and project ahead uncertainty.
Surface Margin: The surface margin term increases the effective radius of the offset well and accommodates for small, unidentified errors. It also defines the minimum acceptable slot separation during facility design and ensures that the separation rule will prohibit the activity before nominal contact between the reference and offset wells, even if the position uncertainty is zero. Default value is 0.3m or 0.984ft.
Projection Ahead Uncertainty: Quantifies the 1 standard deviation uncertainty in the projection ahead of the current survey station. The size of this value represents uncertainties such as directional sensor to bit distance, survey interval, angular control from the BHA, drilling experience in the current formation and the operator’s general attitude towards risk. Default value is 0.5m or 1.64ft
6.2.4 - Alert Separation
Allows the user to set a minimum allowable separation distance (MASD) for wells under the selected operator. When creating an anti-collision report or using the Real Time Anti-Collision tool, if the centre-to-centre distance between the reference well and an offset drops below the MASD, the user will receive a warning.
Minimum Separation: The minimum allowable centre-to-centre distance between the reference well and an offset.
Plus Cone Of Expansion / 1000: The minimum allowable distance will increase, every 1000 units of Measured Depth, by the value entered here. The minimum value is 5.
The formula for the minimum allowable separation distance is as follows:
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