- GeoSteering Service
Geosteering service for drilling oil and gas horizontal wells with any complexity, at any part of the world.
- GeoSteering Software
Software for real-time Geosteering of horizontal wells. Easy to learn and operate due to unique interactive interface.
What is Geosteering?
Geosteering is a real-time process of wellbore trajectory correction aimed to maximize pay zone penetration. Steering decisions are based on real-time MWD/LWD data analysis performed in specialized geosteering software. The service runs in 24/7 mode covered by two geosteering engineers in two 12 hour shifts.
Why do we need Geosteering?
Errors and uncertainties inevitably accompanying process of planning and drilling a well become critical when dealing with horizontal wells because their magnitude becomes compatible to the size of target interval significantly increasing the risk of losing part or even entire borehole outside the pay zone.
Mentioned uncertainties are normally consisting of geological and geometrical components. Geological component include seismic resolution, formation dip uncertainties etc. while geometrical uncertainties are related to trajectory drilling, calculating and extrapolating process. For example for the average horizontal well 3000m long the total TVD uncertainty can be up to few meters.
Why do we need synthetic logs?
While drilling wells with inclination close to 90 deg. vertical logs correlation became inefficient, because the borehole is almost parallel to formation layers and do not produce an informative TVD log. However if formation is not horizontal the correlation problems will be faced much earlier – at landing stage. This is caused by TVD log distortion. Even few degrees formation dip will produce a tangible distortion because of the impact of trajectory high inclination itself. Such distortion leads to correlation uncertainties while landing and can result to wrong identification of marker layers. In that way dealing with high inclinations while landing and drilling the horizontal section vertical logs correlation is not efficient and the most powerful method will be synthetic VS actual logs correlation.
In this method the engineer operates with geosteering model - x-section build along the planned trajectory (Pic.1). The x-section structural surfaces are usually imported from 3D geological model or built manually and formation properties are propagated from the closest offset well or pilot hole.
Having built this way geosteering x-section one can model a correspondent to formation properties log responses along the well trajectory. These logs are called synthetic or forward modeled logs.
On pre-job stage geosteering model with synthetic curves can be used to analyze possible drilling scenarios with different geology behavior. For example to model logs response while crossing the top or bottom of the target or drilling throw the fault. Such analysis allows to estimate possible risks and select appropriate real-time logs set to successfully steer the well while drilling.
While drilling actual real-time logs became available and displayed on according tracks. After actual trajectory is loaded the synthetic curves will be automatically calculated along it. Thus while drilling we can compare synthetic and actual logs along the actual drilling trajectory. If on the drilled interval synthetic and actual curves are match it means that on this interval the model reasonably represent the actual geology drilled if not than model does not and it requires corrections (Pic 2). By changing dips or thicknesses the geosteering engineer is trying to achieve acceptable logs match. And after that, considering updated structure and relative borehole position the engineer recommends trajectory corrections.On pre-job stage geosteering model with synthetic curves can be used to analyze possible drilling scenarios with different geology behavior. For example to model logs response while crossing the top or bottom of the target or drilling throw the fault. Such analysis allows to estimate possible risks and select appropriate real-time logs set to successfully steer the well while drilling.
Software main features
The main objective for any geosteering software is to work efficiently in real-time under very limited timing that’s why every feature is designed to be easy and quickly executed.
Below are few main features which make “Geosteering Office” so efficient and user friendly.
- The software database is a single project file that stores all data that used during work with particular well. This file allows you to quickly send it via e-mail (the average file size 3-7 MB) to colleagues during crew change and to the Customer if necessary to dispute the issue.
- Automatic saving of the database. To avoid data and time losses while drilling, any loaded data and performed changes are saved automatically. Thus in case of occasional PC shut down/reboot the user will not lose the unsaved work. Any time a backup copy (similar to restore point) can be saved as well. In addition, when other person opens the project file all windows and views will be shown exactly the same as it was closed making it much easier to start the work after handover.
- Universal data import module. Universal module allows you to import the borehole trajectory in almost any text or table form without pre-formatting. The program automatically recognizes the desired columns (MD, Incl, Azim) and loads it into the project. Well log data in LAS format imported automatically by selecting the desired curves once.
- 3D geological model data import. Software has ability to load structural surfaces from 3D geological model to create a structure surface on the geosteering scenario. The surface could be loaded in CPS-3 grid or Irap classic grid formats.
- Vertical correlation plot. There is a fully functional vertical correlation plot. It allows you to display and format the offset well’s logs, work with markers and well-to-well correlation.
- Interactive synthetic logs recalculation.When you change the geometry of the surfaces on the cross section, synthetic logs interactively reconstructed simultaneously with the movement of the mouse. This allows much faster and more precisely parameter selection (formation dip angle, TVD or layer thickness) rather than step-by-step method when the desired parameter is selected discretely.
- Work with any log curves. The program works absolutely with any logging curves that can be represented in LAS. It can be LWD logs and mud logging data.
- Working with lithology interpretation results. Along with the geosteering modelling based on formation properties there is the possibility of creating a two-dimensional model from lithology interpretation results and use these data in synthetic and actual data for geosteering the well.
- Azimuthal data module. The program offers a fully functional module to work with azimuthal logs (images) in digital form in order to determine the formation dips and true dip. The calculation result is displayed on the geosteering cross section for 2D model analysis simplicity.
- WITSML Protocol support. Along with the standard data loading through the LAS files, the program can get the data from the rig in real-time using WITSML Protocol. (It is fully tested with WITSML servers from Petroviser and Schlumberger InterAct).