Specialisten in BodemonderzoekSpecialisten in Bodemonderzoek
TISA 3D Geosteering/MWD
As a geosteering tool, TISA 3D has a clear advantage over conventional EM (Electro-Magnetic) technology. Most geosteering/MWD (Measurement While Drilling) techniques are not EM-based, such as ABI (At Bit Inclination), PWD (Pressure While Drilling), gyroscopic logs and magnetic logs. TISA 3D is the only method of the EM family with such geosteering capability. TISA 3D will guide drilling through thin pay zones at a fixed distance to the bounds of the reservoir or to adjacent boreholes as in a SAGD (Steam Activated Gravity Drainage) configuration. Existing LWD (Logging While Drilling) logs measure the borehole wall or its direct vicinity in a reactive geosteering configuration, thereby steering towards reservoir re-entry only after reservoir exit.
Examples of ‘reactive’ LWD’s are density, gamma ray, FMI (Formation Micro Imaging) and acoustic logs. TISA 3D enables proactive or predictive geosteering, seeing the reservoir bounds in advance of drilling. This is not limited to only conventional reservoirs and traps but e.g. faults and salt dome flanks are imaged just as well.
TISA 3D looks deep into the reservoir
Proactively keeps track of the reservoir geometry
TISA 3D BHR can be part of MWD in the BHA (Bottom Hole Assembly) of the drill string
Application of TISA 3D in a Steam-Assisted Gravity Drainage (SAGD) system
SAGD is a technique in which heavy oil or tar is gained from sandstones, by injecting steam into the reservoir in order to lower the viscosity of the oil and accordingly produce the oil. Usually two horizontal wells are drilled, in which the upper well injects the steam. The lower well produces the oil (see Figure below). Vertical separation between both wells is typically between 4 and 6 meters. If this separation becomes too high or too low, the efficiency of the system drops significantly. This is where TISA 3D can be of help. Once the first well has been drilled, the tool can be applied in the second well in order to keep the second well on track. This way the risks involved with vertical separation are reduced considerably and due to the increase of the system efficiency, more oil can be extracted. Keeping in mind that a SAGD-based system typically involves multiple wells, even small increases in extracted volumes per well can have major consequences. The added value of the TISA 3D borehole radar is therefore promising.