Bulletin GeoHorizon

 
The concept of common stratigraphic framework was previously introduced to construct and cross-validate multilayer static and dynamic petrophysical models by invoking the interactive numerical simulation of well logs both before and after invasion. This article documents the successful implementation of the common stratigraphic framework concept to examine and quantify the effects of mud-filtrate invasion on apparent resistivity, nuclear, and magnetic resonance logs acquired in the San Martin, Cashiriari, and Pagoreni gas fields in Camisea, Peru. Conventional petrophysical interpretation methods yield abnormally high estimates of water saturation in some of the reservoir units that produce gas with null water influx. Such an anomalous behavior is caused by relatively low values of deep apparent electrical resistivity and has otherwise been attributed to the presence of clay-coating grains and/or electrically conductive grain minerals coupled with fresh connate water. Concomitantly, electrical resistivity logs exhibit substantial invasion effects as evidenced by the variable separation of apparent resistivity curves (both logging-while-drilling and wireline) with multiple radial lengths of investigation. In extreme cases, apparent resistivity logs stack because of very deep invasion. We diagnose and quantify invasion effects on resistivity and nuclear logs with interactive numerical modeling before and after invasion. The assimilation of such effects in the interpretation consistently decreases previous estimates of water saturation to those of irreducible water saturation inferred from core data. We show that capillary pressure effects are responsible for the difference in separation of apparent resistivity curves in some of the reservoir units. This unique field study confirms that well logs should be corrected for mud-filtrate invasion effects before implementing arbitrary shaly sand models and parameters thereof in the calculation of connate-water saturation.
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Explorer Article

 

Stimulating. Inspirational. Fantastic. Unforgettable. Those were the words used to describe the Latin America Region Student Chapter Leadership Summit (LAR-SCLS) held in early November at the Peruvian Geological Society in Lima, Peru.

American Association of Petroleum Geologists (AAPG)
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Discoveries were comparatively sparse, but they persisted steadily throughout the year. Here are some of the more significant discoveries of the past year.

American Association of Petroleum Geologists (AAPG)
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Explorer Director’s Corner

 

It’s a big world out there and AAPG has Members living and working in all corners. It’s our pleasure to serve them as they explore and produce oil and natural gas to fuel the planet.

American Association of Petroleum Geologists (AAPG)
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Explorer Emphasis

 
While many are working to forecast when the price of oil might reach $80 a barrel again, renowned international strategist and geopolitical analyst Peter Zeihan, the author of “The Accidental Superpower,” predicts in stunning detail the rising and declining energy plays of 2025 and the countries that will ultimately triumph as the world’s leading producers.
American Association of Petroleum Geologists (AAPG)
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Some highlights from international activity in 2014.

American Association of Petroleum Geologists (AAPG)
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Location, location, location. In the sales world, it’s the secret to success. You can say the same about exploration – except there have been times in Latin America when finding a location was the secret.

American Association of Petroleum Geologists (AAPG)
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Winning Hearts and Minds: Colombia and Latin American prospects offer high promise and difficult hurdles in the form of local political and public resistance.

American Association of Petroleum Geologists (AAPG)
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The Santos and Campos basins continue to be the world's hottest spot in deepwater and ultra-deepwater exploration.

American Association of Petroleum Geologists (AAPG)
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Explorer Foundation Update

 

It has a new name, a new energy and a new lineup of experts, all primed to spread geoscience knowledge around the world. “It” is AAPG’s newly named Global Distinguished Lecture Program – emphasis on the “global” – which dates back to 1941 but continues to be the Association’s flagship initiative for offering the latest in geologic science to AAPG affiliated geological societies and universities.

American Association of Petroleum Geologists (AAPG)
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