Petrophysical characterization of a Jurassic sedimentary unit associated
to a foreland basin proposed for CO2 geological storage
in the Tampico-Misantla Oil Province, Mexico
Abstract
We present a reinterpretation of a geological section in the
Tampico-Misantla oil province made with the purpose of selecting and
evaluating possible sites to implement a Geological CO2 Storage (GCS) in
the Jurassic sedimentary units. Specific parameters of the reservoir
such as porosity, permeability, fluid content, temperature, and
overburden pressure were estimated from a database of drilled oil wells,
core descriptions, laboratory tests, and analogue outcrop descriptions.
Previous data indicated porosity values ranging from 6% to 12%, and
relatively low permeability values <0.001 mD for calcareous
sand and clay-silty bearing layers. Reinterpretation of a geological
section involving the main lithostratigraphic units, from Cenozoic
sediments to Jurassic metamorphic rocks, was made based on geological
maps, geological contacts, and seismic data. Petrophysical properties
were obtained from well logs available (Neutron, DTCO, Gamma Ray,
Resistivity) and compared with laboratory measurements in cores from
wells and outcrops. A model of regional petrophysical facies for the
reservoir and seal units was developed by using selected physical
properties in relation with the regional geological context. Five
petrophysical facies distributed across the study area were identified
in the reservoir including calcareous sands, quartz bearing sandstone
and quartz bearing conglomerates for the reservoir, and bituminous
shales and limestone for the shale units covering the reservoir.
Permeability and porosity values at the reservoir scale were estimated
from well logs using methods available in the literature and then
compared with the laboratory tests. Two porosity estimations were
computed from well logs: Neutron porosity (NPHI) and Sonic Porosity
(PHITS) with results ranging from 0.1 % to 16%. Estimated permeability
yielded a range of 0.001 mD to 15 mD. The results suggest that the
Jurassic units are a suitable reservoir since geological traps and
specific depositional facies distributed in the basin have the required
porosity and permeability values suggested for efficient CO2 storage.