7.0 - Surveys Tab
7.1 – Vertical section
This part of the tab allows the user to specify how the vertical section is calculated. The vertical section is displayed on the Section View Plot, so changing these parameters will change how the surveys are displayed. Parameters in this section have no effect on any calculation module.
Vertical Section azimuth – The azimuth of the vertical section in degrees
Origin NS – The origin NS where the vertical section is calculated from in local co-ordinates. This value is usually zero if the vertical section is calculated from the well head location.
Origin EW - The origin EW where the vertical section is calculated from in local co-ordinates. This value is usually zero if the vertical section is calculated from the well head location.
7.2 – Survey Selection
This section defines which surveys are being displayed in the survey grid. There are three options:
Actual surveys – Usually surveys taken while drilling
Well Plan – Plan or surveys used when the well was in the planning stage
Raw surveys – Raw MWD surveys, this page is used for survey corrections such as MSA, SCC and SAG
Note that when modelling a well where only one survey listing or plan is present, it does not matter if the surveys are entered in well plan or actual.
7.3 – Raw Survey Data
The data in this section is used for the Short Collar Correction (SCC) and Multi-Station Analysis (MSA) modules and the well path magnetics calculations. The data in this section only affects surveys in the raw survey grid.
Latitude - Required to calculate the SCC Delta Azi in the Magnetic Spacing Calculator
HL Ref – The reference magnetic field strength in micro Tesla (µT). This is used for the SCC, MSA and magnetic spacing calculations. This value is usually obtained from the well planning department and a program such as IGRF, BGGM or HDGM.
Dip Ref – The reference magnetic dip angle. This is used for the SCC, MSA and magnetic spacing calculations. This value is obtained from the well planning department and a program such as IGRF, BGGM or HDGM.
TAC – Total Applied Correction. This is the correction applied to raw survey azimuths and is calculated automatically, depending on the north reference and the value of grid convergence and magnetic declination.
Grid – Grid Convergence. This value comes from a well planning package and is the angle between True North and Grid North from True North. Note this is the inverse of Grid correction. The two should not be confused.
Dec – Magnetic declination. This is angle from True North to Magnetic North from True North and is used to calculate the TAC and the magnetic azimuth for magnetic interference calculations. This comes from a package such as IGRF or BGGM.
North – The north reference the surveys are referenced to. Either true or grid.
Inclination to use – This is the inclination used by the program to calculate the TVD, NS, EW, VS, TF, DLS, BR & TR values. The user can choose between Sag Corrected and Raw. This option only affects the raw surveys.
7.4 – Survey Corrections
This section defines parameters for the SAG correction module and the well path magnetic interference module.
Offset – The distance from the bit to the MWD directional sensor. This is used for well path magnetic interference calculations and SAG calculations.
Inc Start – If inclination range is specified in the Calc. type combo this is the 1st inclination value to be calculated.
Inc Stop - – If inclination range is specified in the Calc. type combo this is the last inclination value to be calculated.
Inc Step – This is the step value used for the inclination range calculation
DLS – The hole curvature used for single and inclination range calculations
Inc – The inclination use for single calculation
Calc Type –
Single – Calculates SAG & BHA Analysis for a single inclination
Inc Range – Calculates SAG & BHA Analysis for a range of surveys specified by inc start, stop and step
Surveys – Calculates SAG & BHA Analysis for the survey grid selected, curvature is derived from the surveys themselves. If the raw survey grid is selected the corrected inclinations will be displayed in the grid as well as the delta inc.
7.5 – Main Survey Grid
The main survey grid is where all the actual survey data is entered. The survey grid has the same grid controls as all other grids in Innova engineering, with insert delete and copy and paste functions. Surveys can be entered in a number of ways:
Manually typing in each survey line by line
Importing surveys from an existing file using the survey import tool
Copy and pasting data from the clipboard
Depending on the survey selection the survey grid will display different information. If raw surveys are selected and a valid Ref HL and Ref Dip are entered the short collar correction algorithm will automatically run and update every time a change is made to the grid or ref HL and Dip. Surveys which fall out with the QC limits specified will be highlighted in red.
7.5.1 - Tortuosity
This option is only available for Actual and Well Plan surveys and cannot be used with raw surveys. In some situations, it may be necessary to add tortuosity to a well plan or survey to better simulate real life conditions. Well plans which contain purely vertical sections are a typical example of this.
Tortuosity can be applied to the whole wellbore or to one specific section.
Apply Tortuosity – Select this box to enable the tortuosity options
Sinusoidal – Tortuosity will be applied in the form of a sine wave. The inclination and azimuth vary by an amount equal to: A sin(2π*(∆MD/T)). The maximum dogleg variation is 4A/T
Random – The inclination and azimuth vary independently in the range ±A every depth interval T. The maximum dogleg variation is 2A/T.
Depth Range – Select this box to enable the Depth Range options. If this is not selected, tortuosity will be applied to the whole survey or plan.
Period Length – The length of one cycle of the curve.
Start Depth – First depth at which Tortuosity will be applied.
End Depth – Last depth at which Tortuosity will be applied.
7.5.2 – Calculated Survey Data
This option is only available for Actual and Well Plan surveys and cannot be used with raw surveys. This section gives a breakdown of the selected surveys every 10ft or meters, and is a representation of the survey data used in the calculations. If tortuosity has been added to the selected survey, then it will be included in this listing.
7.5.3 – MSA
This radio button opens the Multi-Station Analysis dialogue. This is discussed in more detail in Section 4.5.10 - Multi Station Analysis.
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