The importance of bringing on stream Russia’s unconventional hydrocarbon resources has been duly recognized by local majors. OGE asked geophysical experts to share their views on how to unlock the vast potential of these formations.
Anatoly Tikhonov, Beicip-GeoTechnologies general manager
Oil&Gas Eurasia : In your opinion, what sort of geophysical investigation is still needed to properly understand the Bazhenov?
Аnatoly Tikhonov : I want to note that we need to pay equal amount of attention to Domanik rock as we do to Bazhenov formations. Our leading companies such as Rosneft, Gazprom Neft and LUKOIL have done exactly so. Geophysical survey alone won’t suffice to solve the issue of tight reservoirs study. It’s necessary to collate large volumes of existing geochemical information, including pyrolysis and chloride-bituminate data analysis, as well as survey organic porosity.
One should pay special attention to delineation and study of locations of the so-called “anomalous Bazhenov deposits,” since these zones are characterized by a strong sand seepage of the Bazhenov suite, and, consequently, improved reservoir properties. Geochemistry should by all means be backed up by petrophysical survey. In addition to traditional information on porosity, permeability and saturation, the complex petrophysical survey should reveal the condition of hydrocarbons and the total content of organic matter. Today, such technology is available in the service market.
Thus, traditional methods of geological exploration, such as geochemistry, petrophysics and seismic exploration are challenged by their unconventional use and complexity when studying Bazhenov and Domanik deposits.
The key issue is the use of technology of modeling hydrocarbon systems and basins in an effort to assess the resource potential of oil-bearing suites. An example of such survey is Gazprom Neft’s hydrocarbon systems modeling at Salym field, conducted in an effort to assess the potential of Bazhenov deposits.
OGE: Would different approaches be taken to different parts of the Bazhenov?
Tikhonov: Of course, survey design should be made based on the depth of previous geological knowledge and primarily target oil-producing regions with developed infrastructure and large volumes of geological and geophysical data. Issue #1 in designing is the economic efficiency of survey, which takes into account subsequent decisions on reserves development. In the regions where Bazhenov and Domanik prospects have been confirmed, it’s necessary to prepare integrated pilot projects with an assessment of costs and added value at each stage.
OGE: Is there sufficient 3D seismic? If not, where should more 3D seismic be shot?
Tikhonov: It’s obvious that the regions with existing production, particularly mature fields, where the issue of developing tight reservoirs is the most relevant, are fairly well covered by standard seismic mapping. The seismic survey challenge during additional appraisal of Bazhenov oil is paramount – it needs to provide information on interior structure and elastic properties of layers that are part of the Bazhenov suite, in an effort to assess prospects for geological exploration and development. With developed above-ground infrastructure in place, this requires gathering wide-azimuth, high-density seismic data with the mapping resolution sufficient to survey interior