Pedro Antonio Romero1,
(1) PDVSA-INTEVEP, N/A, Bolivia
(2) Universidad Simón Bolívar
(3) PDVA E&P
Abstract: RMN as a tool for reservoirs characterization and lithofacies recognition
The NMR T2 distribution has been attributed to be related to pore geometry and grain material composition. NMR Studies have been carried on core samples and logs of Misoa C4-C5 reservoirs with the application of determining the characteristic petrophysical properties in the context of a water injection program.
The reservoirs are characterized for three different sandstone facies: Very fine, ripple sandstone (S11), fine to medium ripple and herring bond sandstone (S11- S3) and medium cross-laminated sandstone (S3). C4 was deposited in a lower delta plain and C5 in a delta front tidal delta environment. C4 is characterized by channel and bar sand deposit. C5 sand is deposited in distal tidal ridges.
The facies were petrographycally described to define pore and throat size. Pore size in the S11 range between 0.0125 mm and 0.025 mm and throat size range between 0.0025 mm and 0.00625. The S11-S3 facies pore size range is from 0.025 mm to 0.1 mm and throat size range from 0.00625 mm to 0.025 mm and in facies S3 pore size range is between 0.125 mm and 0.075 mm and throat between 0.00875 and 0.01875 mm.
The T2 distributions have been found to be in a very close correspondence to the facies classification. This result allows recognizing facies by means of their T2 distribution pattern, improving the application of the NMR technique in the sedimentology. This found have helped to redefine the petrophysical understanding of the reservoir and to improving the lithofacies discriminated determination of porosity and permeability.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana