Evolution Towards more Advanced Organic Rich Mudrock Workflows & Petrophysical Models

Abstract

Advances within reservoir characterization of unconventional organic rich mudrocks within North America has provided a basis of evolving workflows and more advanced petrophysical models. Through advanced reservoir characterization nanoscale imagery analyses (FIB SEM) it has been recognized that multiple types of micro and nano porosity systems are present, each likely with separate differing system permeability to fluids and gases, as well as net hydrocarbon and water saturation. This observed porosity and permeability system complexity includes the distribution of hydrocarbons and water within insoluble organic matter (kerogens or pyrobitumens), soluble organic matter (bitumen), inorganic pores (inter-crystalline & inter-particle), and natural fracture pores (open to partially open). Circled in red (Figure 1) are where the micro and nano porosity systems occur within the identified compositional components. The four pore system types (1, 2, 3, 4) are where expected variation by pore system type of hydrocarbon (including bitumen) and water saturation. Expected hydrocarbon phase (Black Oil, Volatile Oil, Condensate, Wet Gas, Dry Gas, and Secondary Cracked Gas) is also directly related to the kerogen transformation ratio. The challenge within reservoir characterization and formation evaluation of these complex reservoir systems includes the upscaling of the characterization of the advanced nano and micro pore-scale imaging and understanding correlation of nano and micro porosity to formation evaluation tools and net producible zones within these targets (M. Bratovich, F. Walles, 2016). A measurement basis link within this reservoir characterization analysis includes applications of advanced geochemistry linked to FIBSEM imagery analysis. The integration of critical reservoir micro through nanoscale porosity and permeability development as well as incorporating net hydrocarbon phases attributed to kerogens, bitumens and interparticle / inter crystalline systems can be utilized for the optimization of vertical zone lateral placement (singular or stacked) and or lateral stimulation and completion. Assessment value includes targeted technology applications (Wireline, LWD, surface logging) for spatial optimization for improved capital efficiency and hydrocarbon production. This presentation will provide a proposed framework basis of investigation for the integration of advanced geochemical approaches to begin to determine the distribution of these different porosity and permeability systems for improved reservoir characterization.

AAPG Datapages/Search and Discovery Article #90333©2018 AAPG Middle East Region, Shale Gas Evolution Symposium, Manama, Bahrain, December 11-13, 2018