Unconventional petroleum resources constitute an increasing frontier of reserves additions as conventional production declines globally. In this era of environmental conservation and sustainability concerns, new resource development efforts confront energy, emissions, and economic intensities. Clearer understanding of resource development choices and their implications can be gained by quantifying these intensities through a systematic approach which allows effective comparisons of alternative energy systems to be drawn in the context of policy and/or business decision-making. Yet, existing assessment studies often lack transparency or do not furnish detailed methodological descriptions of the approach needed for transferability or validation of results in subsequent studies which evaluate impacts of our existing and emerging energy systems design decisions. The combination of analytical and semi-analytical modelling holds great potential to address current methodological challenges in assessing impacts of unconventional resources development. Focusing on shale gas and oil sands resources, this thesis presents new modelling tools and assessment frameworks to quantify and compare impacts of operations and technologies needed during development and recovery of these energy resources. The first part of the contributions evaluated potential environmental impacts of flowback methane in the U.S. and Canada to be 2347 and 1859 Mg CO2e per completion, respectively. The second part assessed contributions of all preproduction activities to overall energy and environmental intensities, highlighting drilling and flowback intensities as major sources. The third and fourth contribution chapters investigated the role of innovation to improve oil sands production and demonstrated the application of carbon dioxide utilization to mitigate impacts of unconventional oil and gas production, respectively.