An innovative combined MT and seismic onshore survey has led to a reef discovery in Russia.
St. Petersburg State Mining Institute (SPMI) has carried out seismic and MT exploration since 2004 over a large Devonian reef prospect in the Nenets Region in the well-known Timan-Pechora hydrocarbon province of northwest Russia.
Phoenix assisted SPMI with field work and interpretation of selected data, under the umbrella of the long-term cooperation agreement signed in 2002 (see Issues 24 and 30 and the Phoenix website
). The results were presented at the 6th Modern Electroprospecting Seminar at SPMI in March, 2008.
Although Timan-Pechora is a relatively mature oil and gas province with many producing fields of various ages, there are large fields, both onshore and offshore, yet to be developed in the Nenets region. Estimated remaining known recoverable reserves are at least 15 billion barrels of oil equivalent.
Russia is rapidly developing new production from this region, targeting approximately one million barrels a day. One advantage of Nenets is the relative ease of export by tanker compared to delivery through the long, costly pipelines required for discoveries in other areas.
The Russian oil company Lukoil is a major player in the region, with a recent discovery of 500 million barrels. Lukoil has built a pipeline and a marine export terminal, Varandey, on the Barents Sea coast. Ice-breaking tankers load oil from a special fixed offshore ice-resistant terminal at Varandey for markets in western Europe and North America.
The figure shows transverse sections through the reef as seen by MT (left) and seismic (right). The lines are approx. 6km long. The top of the reef is approx. 3000m subsurface. MT data shows that the upper portion of the reef is more resistive (green, yellow) than the seal (red, orange), suggesting the presence of hydrocarbons. The lower portion and flanks of the reef are more conductive (red, orange) than the upper portion, suggesting formation brines below the hydrocarbons. The two different techniques, interpreted completely independently, complement one another: seismic shows a more reliable configuration of the reef, and the MT resistivity suggests the degree of hydrocarbon charge.
The first MT lines were located based on the interpretation of older seismic data. However, the initial MT results did not agree with the old seismic interpretation. The first well (based on the old seismic data) was drilled on the flank of the reef, and did not find economic hydrocarbons within the reef. After reprocessing with modern software programs, the seismic result agreed more closely with the MT result.
A second well was drilled at a more favorable location defined by MT and reprocessed seismic, with satisfactory results. Detailed results are confidential.