Directional Survey Plus
The most accurate spatial representation of well path from surface to total depth
Raising the Standards for Directional Survey Quality
Well path control from directional survey data is an essential data type in oil and gas for interpreters, land departments and reservoir engineering efforts. In order to be interpretation-ready, directional survey data must move beyond simple data capture of measured depth, azimuth and inclination.
TGS’ Directional Survey Plus (DS+) data are thoroughly researched, re-processed and standardized to create the most accurate spatial representation of the well path, from surface to total depth.
TGS tracks the source of all data received for processing, including when survey data is gathered from multiple vendors for the same well. This allows unique runs of information (logs, surveys, etc.) to be segregated by data type, service company, date acquired, run type (complete, partial), etc. Each data element can also be given a relative ranking regarding order of precedence, allowing the processing staff to use one vendor’s data over another depending on the situation (e.g. using data provided directly from the operator over that submitted via a contractor or vice versa) during the merging and composing process.
Keys to Accurate Directional Survey Data
Complete - No More Missing Wellbores - In the US, 15-20% of drilled wellbores are missing from all industry well data sources. TGS recognizes the importance of all wellbores being identified for the interpretation process, drilling activities and to the integration of all well data types.
Spatially Correct - Well paths keyed in from directional surveys look nice, but a high percentage of the time the well path is not in the right place. Directional survey data must be standardized to the same North reference, same zone (if grid referenced) and the same datum (and more) to plot correctly. Directional surveys do not come standardized from the industry’s directional survey contractors. TGS’ Directional Survey Plus (DS+) solves those standardizing requirements (see reverse).
Integration Ready Data - Successful integration of all the various well data types available on a well is an industry problem and is improved when all wellbores are recognized (below). TGS is also working with other industry sources of well header data to support data integration success by operators.
Global Data Coverage Online
Current inventory is available for immediate download on TGS’ R360TM. Coverage includes many of the hottest basins in the US and around the world. TGS is expanding its US databases every day and supports DS+ processing worldwide.
What Data is Captured?
- Primary and calculated station data - The primary directional survey measurements of 1.) Measure Depth, 2.) Hole inclination and 3.) Hole Direction are captured from available directional surveys and used to recalculate and output a final 'composited' directional survey. Additionally, tie points information (MD,TVD, N/S Offset, E/W Offset) when needed for spatial positioning are captured. All depth points are captured.
- Directional survey original 'runs' - all individual runs in their entirety (all depth stations) are captured, as well as the critical run/ tool attributes, including their original units, North references, calculation methods, survey company, run date, ect.
- Critical data field quality tags - Directional survey reporting on contractor's hardcopy surveys has been subject to no standards over the years and many directional surveys are found lacking important information. In the data capture process, a number of individual data elements (like North reference) benefit from additional metadata. While every run and point have a captured original North reference, these references are further defined as stated (reported explicitly by the survey company in the directional survey report), inferred (not explicitly stated but can be determined confidently based on other information data on the survey) or assumed )based on dates, historical trends, or other criteria).
- Well log data - Additionally, TGS' extensive well log library is leveraged as an asset for ensuring down-hole and header data accuracy by capturing critical dates and depth value control, as well as indicators of wellbore number, drilled, sequenced, elevation, ect.
Directional Survey Plus Output
- Composite output - TGS evaluates all the available surveys run on a well and creates a final composited directional survey that extends from the surface (0 depth) to the well's total depth. It contains all the standard directional survey data fields generally reported by the industry's directional survey contractors. In a well that has multiple sidetracks, each wellbore is 'standalone' - meaning that each wellbore is separately composited from surface total depth. In a small percentage of the directional survey inventory, TIE points are required to start the composited directional survey. This occurs normally when the upper run has been lost, misplaced, never submitted, ect. and the surface or zero depth and need to be spatially 'tied' with a TIE point.
- North references - Historically, directional survey data as reported on hardcopies is a mixed collection of Grid North, True North or Magnetic North data. If not standardized to a common North reference, such data creates misleading and erroneous well paths. TGS processes the composited directional survey data and delivers all the wells referenced to True North, or also all the wells referenced to Grid North. If Grid North , the surveys are output normally to a default projection and zone based on the surface location area.
Directional Survey Plus Calculation Method
The most commonly used calculation algorithm today is Minimum Curvature. Legacy data that were originally reported in various older methods, like Radius of Curvature, Tangential, Average Angle, ect. are standardized to Minimum Curvature.
Final Data Output (* -TGS Default)
- ASCII Record A (well header, location and elevation) and Record C (directional survey station data) files pairs*
- TGS Full ASCII (Record A and Record C and includes survey run original and output parameters)*
- 12 or 14* digit US API Support , 16 digit UWI Canada
- PPDM 3.8 - TGS can work with clients to ensure seamless data importing into PPDM data models
- WITSLM 1.4.0 (contact TGS for the TGS WITSLM Specification documentation for more details)
Directional survey Plus file deliveries can also support multiple simultaneous deliveries of the same data. If there are multiple software packages, multiple project configurations, multiple departments or multiple locations using the same data, TGS recommends taking delivery of multiple delivery file formats.
Directional Survey Plus Quality Control and Editing
TGS uses state-of-the-art data entry and edit system for directional survey generation. Double data entry processes (instead of single entry review) further ensures raw data entry accuracy. Extensive iterative recalculation methods are used to eliminate errors as well as database / system constraints on inappropriate values.
Well Integrity Validation
- Well information such as API number, operator, well name, well number, spud date and date at TD, ect. are verified for accuracy.
- Common data are collected to ensure data consistency and assist in making good assumptions on historical data (including values which assist in the data processing, but are not required as part of the data deliverable, e.g. Rig Name/ Number for help with KB elevations.)
- Multiple elevations parts are captured including Ground Level, Kelly Bushing, Rotary Table, ect. and used to check the final MSL-KB elevation.
- New boreholes are created, even if unrecognized by the regulatory agencies, which is a critical component to accurate Directional Survey Plus data.
- 70-series (API number characters 11-12) are used to identify otherwise unrecognized boreholes by the regulatory bodies.
TGS participates, contributes to or otherwise leverages industry standards in order to ensure data consistency. Industry groups which impact directional survey include: IOGCC, PPDM, API D12a (now sponsored by PPDM) and Energistics' WITSML.