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.
Added on 28 February, 2013
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.
Added on 01 December, 2014
Discoveries were comparatively sparse, but they persisted steadily throughout the year. Here are some of the more significant discoveries of the past year.
Added on 01 January, 2014
What’s next? Leaders of three AAPG Regions talk about anticipated activity and potential challenges their areas face in 2011.
Added on 01 February, 2011
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.
Added on 01 October, 2014
Winning Hearts and Minds: Colombia and Latin American prospects offer high promise and difficult hurdles in the form of local political and public resistance.
Added on 01 March, 2014
The Santos and Campos basins continue to be the world's hottest spot in deepwater and ultra-deepwater exploration.
Added on 01 August, 2013
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.
Added on 01 October, 2014
Explorer Regions and Sections
With expertise as both a professor and consulting geologist, AAPG President Paul Weimer’s background is well-aligned with the energy industry renaissance currently under way in Latin America.
Added on 01 August, 2011
Colombians elected Juan Manuel Santos as their new president on June 20, the day AAPG’s presidential delegation landed in Bogotá for a whirlwind tour with both tactical and strategic importance.
Added on 01 August, 2010