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To predict the petroleum potential, we used stratigraphic, tectonic, lithologo-facies, and geochemical criteria. We have considered their significance and estimated the petroleum potential from a total of criteria. The structures of the Toarcian, Pliensbachian, and Hettangian-Sinemurian regional reservoirs of the Lower Jurassic have been characterized. The low petroleum potential of the reservoirs is due to the following factors: intricate structure, low and very low values of capacity-filtration parameters of reservoir rocks, widespread sealing beds of poor and very poor quality, low oil-generating potential of oil source rocks, and a high degree of catagenetic transformation of OM, as well as nearly ubiquitous saturation of reservoirs with formational waters.

Time-domain electromagnetic (TEM) soundings were performed in the vicinity of a plant in Saratov town, Russia, to detect hydrocarbon pollution of groundwater and to trace possible pollution flows in drainage zones. The presence of hydrocarbons in rocks is indicated by high electrical resistance and induced polarization (IP) effects found in many TEM curves. Calculations show that the polarizability is the ratio of the excess electrical conductance to the electrical conductance in pores. Relaxation time was found to be controlled mainly by the radius of pores in water-saturated sediments. IP effects can be recorded by TEM soundings in wet sediments with imperfect phase relationships if the pore radius is the in the range of 10

Differential-normalized electrical measurements (DNEM) have shown their efficiency in petroleum prospecting. The method implies detection of oil and gas deposits from polarization anomalies in haloes around rocks altered under the effect of the hydrocarbon pool. Polarization in the geo-electric section is determined layer-by-layer using space and time derivatives of the TEM process and differential-normalized parameters.

The State Unitary Enterprise for Arctic Sea Engineering-Geological Expeditions (SEA ASIGE), Murmansk, carried out surveys in the north-eastern Pechora Sea. As a result, peculiar structures were revealed at the top of the sedimentary cover and anomalous features in the bottom topography. The anomalous bottom features are Pingo-like (Bulgunnyakh-like) rises with the base 20-60 to 100-130 m wide and with a relative altitude of 10-25 m. These rises are drastically highlighted on the smooth gentle surface of the bottom. They are made up of frozen ice-saturated deposits. On the domes of diaper-like uplifts, the roof of frozen icy deposits occurs at a depth of less than 0.5 m beneath the surface of the bottom, and their thickness reaches 100 m and more. At the sites between these uplifts the roof of the frozen grounds lies at a depth of about 15-20 m from the bottom surface with the thickness of the frozen unit of about 30 m. One of the wells drilled between diaper-like uplifts penetrated an overpressure gas accumulation at a depth of 50 m below the bottom surface.

A geographically related database called MAGIC has been developed, using GIS (Geographic Information System) technology, for MArine Gas seeps and seep IndiCators. A complementary bibliographic database (GASREF) stores details of related publications. The databases include data relating to natural seabed gas seeps and features such as pockmarks, cold seep communities, and methane-derived carbonates which are known to be found in association with seeps. The databases are compiled from published reports (so far restricted to those written in English), and users are able to interrogate the system for specified features from user-defined areas.

Concentrations of water-dissolved methane were measured on the eastern shelf and slope of Sakhalin. Seasonal variability of water structure is chiefly responsible for seasonal differences in methane concentrations in the water body. In the shelf zone the maximum flow of methane to the atmosphere occurs in the cold season; in summer, it is much weaker. The cold season is also the time when the methane-saturated shelf waters reach intermediate depths on the continental slope. In summer, the shelf waters stop sliding down the slope; therefore, no methane anomaly is observed at intermediate depths. Methane concentrations at latitudinal profiles vary from year to year, which is possibly due to variations in seismotectonic activity of the region.
Our observations are important for calculation of the flow of methane from the Earth's interior to water and from water to atmosphere in the western Sea of Okhotsk. The available data show that there are natural sources of methane supply to the atmosphere which depend on season and seismotectonic activity of fault zones, generators and conduits of methane flows. The methane flows in the Sea of Okhotsk participate in the global process of its supply and increase in the atmosphere, which is, likely, responsible for changes in climate (warming) and destruction of the ozone layer.

Evaluating the importance of natural marine hydrocarbon seeps to global methane budgets requires correctly predicting the gas fraction lost by the seep bubbles during transit through the water column. In the Santa Barbara Channel, California, three widely differing seeps (depth, flux, oiliness) were visited and observations were made of seep gas partial pressures, P_n, near the surface for alkanes to n = 5 (pentane) as well as major atmospheric gases, and up welling flows. It was found that alkane P_n decreased exponentially with alkane diffusivity. Seabed seep gas was available for one seep, and exhibited the same trend. For alkanes heavier than methane, the ratio of the surface to sea floor mole fraction showed a linear enhancement with increasing alkane number. Methane behaved differently because the water column became saturated.
A numerical model was developed to study the sensitivity to environmental parameters of the bubble transport of seep gas to the surface. It was found that seep gas transport is highly sensitive to both up welling flows, dissolved gas concentrations, bubble surface cleanliness, and bubble size. The model predicted that up welling flows increase bubble survivability and transport to the surface. It also predicted that dissolved methane concentrations responsible for pressure higher than 0.01 atm increase bubble survivability. When applied to simulating alkanes, the studies showed that only a narrow range in bubble size could explain the observed alkane enhancements. Thus model predictions were in agreement with the observation that a wide size range of bubbles was not observed at the sea surface.

Under consideration are empirical aspects of the mode of hydrocarbon gases in the Caspian Sea. This paper reports concentrations of gas hydrocarbons in the sea water and bottom sediments of the Caspian Sea and describes patterns of their distribution in the water and sedimentary bodies of the region under study. The revealed regularities served as a base for development of methodology, equipment, and approaches to interpretation of data on gas geochemistry in searching for oil and gas in water areas. In addition to solving the problems of search for petroleum, the experimental study provided a possibility to use the results obtained during gas surveys to solve engineering, ecological, and other problems of national economy. The use of gas survey in industry has been outlined in detail.