Comment on “Benefits of the induced polarization geoelectric method to hydrocarbon exploration” ()

Geophysics ◽  
2010 ◽  
Vol 75 (1) ◽  
pp. X1-X2
Author(s):  
J. C. Wynn ◽  
D. D. Snyder
Geophysics ◽  
2009 ◽  
Vol 74 (2) ◽  
pp. B47-B59 ◽  
Author(s):  
Paul C. Veeken ◽  
Peter J. Legeydo ◽  
Yuri A. Davidenko ◽  
Elena O. Kudryavceva ◽  
Sergei A. Ivanov ◽  
...  

Delineation of hydrocarbon prospective areas is an important issue in petroleum exploration. The geoelectric method helps to identify attractive areas and reduces the overall drilling risk. For this purpose, induced polarization (IP) effects are mapped caused by the presence of epigenetic pyrite microcrystals in sedimentary rocks. These crystals occur in a shallow halo-shaped mineralogical alteration zone, often overlying a deeper-seated hydrocarbon accumulation. Local enrichment in pyrite results from reducing geochemical conditions below an impermeable layer. The imperfect top seal of the accumulation permits minor amounts of hydrocarbons to escape and migrate through the overlying rocks to shallower levels. During migration, hydro-carbons encounter an impermeable barrier, forming an altera-tion zone. Induced polarization logging and coring in wells confirm this working model. Geoelectric surveying visual-izes anomalies in electric potential difference measured be-tween receiver electrodes. The differentially normalized method (DNME) inverts the registered decay in potential differences, establishing a depth model constrained by seismic and petro-physical data. Diagnostic geoelectric attributes are proposed, giving a better grip on chargeability and resistivity distribution. Acquisition and processing parameters are adjusted to the target depth. Encouraging results are obtained in deeper [Formula: see text] as well as in very shallow water. Onshore, a grounded current transmitter is used. Geoelectric surveys cover different geologic settings with varying target depths. The success ratio for predicting hydrocarbon occurrences is high. So far, 40 successful wells have been drilled in Russia on mapped geoelectric anomalies. Out of 126 wells, the method produced satisfactory results in all but two cases. The technique reduces the risk attached to new hydrocarbon prospects and allows better ranking at a reasonable cost.


Geophysics ◽  
2009 ◽  
Vol 74 (4) ◽  
pp. Y7-Y7 ◽  
Author(s):  
Paul C. Veeken ◽  
Peter J. Legeydo ◽  
Yuri A. Davidenko ◽  
Elena O. Kudryavceva ◽  
Sergei A. Ivanov ◽  
...  

Geophysics ◽  
1991 ◽  
Vol 56 (10) ◽  
pp. 1522-1532 ◽  
Author(s):  
Ben K. Sternberg

Our experience with the induced polarization (IP) and resistivity method for hydrocarbon exploration has shown both successful surveys and limitations of the method. Four examples demonstrate a close correlation between shallow IP and resistivity anomalies and deeper hydrocarbon production. In each of these examples, anomalies occurred over the producing fields which have significantly greater amplitudes than the variations in the surrounding background response. Another important result of our research is the development of a geological/geochemical model for the formation of IP and resistivity anomalies over hydrocarbon reservoirs. The two main requirements for formation of IP and resistivity anomalies, according to this model, are: (1) absence of any thick impermeable seals, such as evaporites, above the reservoir and (2) presence of porous, iron‐rich, near‐surface host rocks, such as clastic rock sequences. The IP and resistivity method can be more successfully applied by selecting those areas for surveys in which these two requirements hold. We have also found that the IP/resistivity method for hydrocarbon exploration has significant limitations. Many areas do not appear to have the required geological and geochemical conditions for the formation of IP or resistivity anomalies. IP and resistivity anomalies may also need to be tested with shallow drill holes to separate anomalies caused by hydrocarbon seepage from false anomalies due to other causes.


2013 ◽  
Author(s):  
Nasier Mohamed Fakier ◽  
Hussein A. Al-Helal ◽  
Ali A. Al-Zayer

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