Some technical sessions at SEG Las Vegas 2008 inevitably have proved more popular than others, but Monday’s special session on “Recent Advances and the Road Ahead,” probably took the cake.

Unless you arrived early, due to the crush of knowledge seekers, it was physically impossible to get into the room for the initial presentation, “Seismic Imaging: Today and Tomorrow.” After awhile, the room thinned out just a wee bit, but interest remained high throughout the afternoon, including for two presentations: “Directional Resistivity Tools and Their Business Impacts,” and “CSEM: A Fast-Growing Technology.”

Ian Zhang, Shell international E&P, compared and contrasted recently developed multicomponent induction wireline and LWD resistivity logging tools.

According to a recent article in 'Fuel from Knowledge Central', by Michael Bittar, Halliburton technology fellow, “Since their introduction in the 1980s, conventional logging-while-drilling (LWD) propagation resistivity tools have proved useful in helping land and maintain well bores within hydrocarbon reservoirs by providing resistivity measurements of the formation being drilled.”

However, these LWD tools had lacked the azimuthal sensitivity for directional geosteering or evaluation of complex reservoirs. The latest designs, however, overcome these previous limitations, said Zhang, for both directional geosteering and formation evaluation.

As presented by Zhang, these new tools include wireline induction logging tools such as 3DEX from Baker Hughes and Rt Scanner from Schlumberger. Directional LWD resistivity tools include APR (azimuthal propagation resistivity) from Baker Hughes, ADR (azimuthal deep resistivity) from Halliburton, and PeriScope15 and PeriScope100 from Schlumberger.

These new tools have multiple or 3-component transmitters and receivers and can provide information about directionality and anisotropy. This has led to new applications. The 3DEX and Rt Scanner have been used to detect resistivity anisotropy in a formation, thus better quantifying hydrocarbon-in-place and hydrocarbon recovery. These
tensor wireline tools have also been used for formation angle detection and fracture characterization.

Likewise, the new multicomponent LWD resistivity tools allow deeper investigation depths, and have been used for geosteering and well placement, including reducing unplanned exits from sweet zones.

Further development of these technologies involves both challenges and opportunities, concluded Zhang. Challenges include limitations in data transmission, uncertainty in measurement, and the inability to do evaluations in real time. In the future, though, ultra-deep reading capability, 3-D interpretations, and simultaneous handling of multiple effects should be added to the tool set.

“While we’re seeing wide application of the technology today,” said Zhang, “its full potential is not yet unleashed due to some considerable gaps that the industry must address together.”

In his presentation, Svien Ellingsrud, EM-Consulting, discussed recent advances in controlled source electromagnetic sounding (CSEM) as applied in sea bed logging (SBL) for direct hydrocarbon detection. Currently a US $200 million market, the methodology was originally developed by Statoil.

Hydrocarbons have a higher resistivity than their surrounding sediments, normally consisting of brine-saturated rocks such as shale. In CSEM, a powerful electric dipole source is towed close to the sea floor. The transmitted energy then propagates down through the subsurface. The resistivity contrast of the reservoir then can be recorded by seafloor receivers.

Ellingsrud asked the question, will this technology market continue to grow?

Today, he said, CSEM data is of high quality and acquired with sources that can transmit currents at 1,250 amperes. Due to a new feature, automatic gain, acquired data can cover a dynamic range of more than 180 dB with useful information.

However, he concluded, the technology has to be moved from single 2-D lines to grids and 3-D surveys, and the data must be processed and interpreted by tools such as 3-D inversion and imaging. Further, operations must be run in shallower water depths and data must be integrated with other geophysical methods.

As important, he said, “The industry has to fully accept CSEM and the value it creates for end-users.”