A large volume of high-accuracy aeromagnetic and medium- scale gravimetric surveys has been carried out in West Siberia. Using these data, detailed studies were made of two regions, Agan and Urengoy-Tarkosalin, to dfetermine the relationship of hydrocarbon occurrence to geophysical anomalies. It turns out that almost all the oil and gas fields are located in sectors where gaviy and magnetic minimums coincide. In sectors where gravity and magnetic maximums coincide or where there is only a gravity or magnetic minimumm, oil and gas fields are generally absent. There are exceptions to this generality.
In the Agan sector the Vyngapur and Novogod fields occur within magnetic minimums; no gravity data are available here. Fields that are within areas where gravity and magnetic minimums coincide are Yarayner, Severo-Var'yegan, Tagrin, Kurragan, Agan, Malo-Agan, Samotlor (north part), Gun'yegan, Sredne-Chernogor, Novomolodezh, Khokhryakov, Verkhne- Kolik'yegan, and Malo-Khokhryakov. The Var'yegan, Van'yegan, Kotukhtin, Severo-Khokhryakov, and Malo-Chernogor fields extend beyond the gravity minimums. Exceptions are Zapadno- Var'yegan and Tyumen, which are on gravity minimums and on the flanks of magnetic maximums, and also Yuzhno-Vyngapur, which is on a continuation of a gravity minimum and on a magnetic gradient. Many fields that lie beyond the boundaries of ther Agan sector are located on continuations of gravity minimums.
A similar situation is found in the Urengoy-Tarkosalin sector. Most of the fields there (Urengoy, Samburg, Zapolyar, Russkoye, Yuzhno-Russkoye, Yubiley, Vostochno-Urengoy, Yevoyakhin, Yamsovey, Severo-Komsomol, Novo-Purpey, Vostochno-Yangtin, Komsomol, Gubkin, Zapadno-Tarkosalin, Vostochno-Tarkosalin, Tarasov, Yetypur. Severo-Kharampur, and Yuzhno-Kharampur are on gravity minimums. Only a few fields extend outside these minimums.
Urengoy field practically coincides with the largest gravity minimum. Based on the gravity and magnetic anomalies the field is subdivided into two parts, nrthern and southern. Between them is a narrow structural bridge about 10-15 km wide in the region of the Arka-Tab"yakhn structure. There the local gravity field is zero, and the magnetic field is positive. This coincidence of the Urengoy field with the entire gravity mnmujm suggests that other fields that occupy only part of a minimum may actually be larger than previously thought.
Several fields located just outside the Urengoy-Tarkosalin sector are situated on continuations of gravity lows.
Areas favorable for explolration have been delineated on the basis of this association of oil and gas fields with gravity and magnetic lows.
Taken from Shaposhnikov and Samoletov, 1986; digested
in Petroleum Geology, Vol. 23, No, 9/10, two maps showing
areas favorable for exploration.
Copyright James Carke 2003. You are encouraged to print out
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