Published in Upstream

Current trend in Geosteering: Where are we heading?

Friday, 09 October 2015 16:50 Written by 

With the growing demand for hydrocarbons in the last 10-15 years there is a major shift in the oil industry where vertical wells have been replaced mostly by highly deviated or horizontal wells. While drilling horizontal wells, accurate and proper placement has become very important as operators are constantly looking for maximum contacts in the reservoir. This has resulted in more reliant and optimized Geosteering operation. Currently about 95% of all horizontal wells in the world are being geosteered. Optimal geosteering is accomplished by selecting the proper combination of logging-while-drilling (LWD) and measurement-while-drilling (MWD) tools as data acquired from these tools are directly deployed for interpreting and monitoring the well.

The procedure

Achieving maximum success in geosteering is only possible through real-time interpretation and modeling of MWD/LWD data while drilling. Additionally, real-time 3D model updates while drilling deliver maximum guidance and assistance in geosteering to the proper well position by predicting the geology ahead of the bit. As a result, well placement risk is reduced because the associated uncertainty is quantified. A meaningful modeling-while-drilling campaign is greatly dependent on three main factors:

  • Uninterrupted real-time data transmission
  • Use of appropriate software modeling
  • Selection of adequate modeling techniques

Critical to the process is a state-of-the-art satellite communication system that helps the geosteerer receive reliable data as quickly as possible from the remote rig. For reliable data transmission, the WITSML format is the most commonly used standard in the industry. Available software packages provide a full range of methods for performing interpretation and model updates while drilling. Each of these software packages has its own limitations and advantages. Thus, selecting the appropriate software is the next most important step in the procedure.

Current trend

The most recent development in this field is the implementation of real-time 3D model updates while drilling for better and more efficient Geosteering results. Operators have realized that such procedure delivers maximum guidance and assistance in geosteering to the proper well position by predicting the geology ahead of the bit. As a result, well placement risk is reduced because the associated uncertainty is quantified.

Log modeling and 3D geocellular property modeling-while-drilling are two widely used variants of modeling-while-drilling. Log modeling generates a series of modeled log responses along the planned well path considering the offset well information whereas 3D geocellular property modeling-while-drilling is comprised of two steps i.e. fine layering and gridding (FLG) followed by property simulation and regular model updates with new real-time log and well pick information. Each of these techniques requires MWD/LWD data, well picks and surface grid information as input and uses different algorithms to complete the modeling. But, to obtain effective results, both the simplicity and the adequacy of the modeling technique play a very important role in the procedure.

Concluding remark

Around the world, recent development of modeling-while-drilling techniques has significantly helped oil companies solve many complex well-placement challenges. In North American unconventional oil and gas industry this techniques are very widely used almost in all wells. It is an extremely useful technique for optimizing horizontal well paths, maximizing well productivity and reducing lost rig time. In addition, it allows professionals from different disciplines, whether in the field or geosteering centers, to work together in an integrated manner to reduce well costs and improve well placement.

Last modified on Friday, 12 October 2018 10:22
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