Applications of Conventional Logs in Low Resistivity Contrast Tight Gas Reservoirs Identification

Abstract:

It’s a great challenge in identifying gas bearing formation from conventional logs in tight gas sandstones due to the low resistivity contrast caused by high irreducible water saturation. Based on the difference of the principles of three kinds of porosity logs (density, neutron and acoustic logs), three porosities difference method, three porosities ratio method, correlation of neutron and density logs and the overlap method of water-filled porosity and total porosity are introduced to identify tight gas bearing reservoirs. In gas bearing formations, the difference of three porosities is higher than 0.0, the ratio of three porosities is higher than 1.0, the correlation between density and neutron logs is negative, and the water filled porosities are lower than total porosities. On the contrary, in water saturated formations, the difference of three porosities is lower than 0.0, the ratio of three porosities is lower than 1.0, the correlation between density and neutron logs is positive, and the water filled porosities are overlapped with total porosities. Considering the complexity of in-suit formation, when the proposed identification criterion are mainly meet, the pore fluid should be determined, field examples show that the proposed techniques are applicable in tight gas formation identification.

• Periodical: Advanced Materials Research (Volumes 734-737)
• Pages: 41-44
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.734-737.41
• Online since: August 2013
• Authors: Xiao Peng Liu, Xiao Xin Hu, Xiao Ling Zhang, Rui Xu, Ling Ling Zhi
• Keywords: Correlation of Neutron and Density Logs, Difference of Three Porosities, Identification, Low Resistivity Contrast Gas Bearing Formation, Ratio of Three Porosities, Tight Sandstone Gas

References

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DOI: 10.2118/163951-ms

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