A Preliminary Energy Return on Investment Analysis of Natural Gas from the Marcellus Shale

Abstract

An analysis of the energy return on investment (EROI) of natural gas obtained from horizontal, hydraulically fractured wells in the Marcellus Shale was conducted using net external energy ratio methodology and available data and estimates of energy inputs and outputs. Used as sources of input data were estimates of carbon dioxide and nitrogen oxides emitted from the gas extraction processes, as well as fuel-use reports from industry and other sources. Estimates of quantities of materials used and the associated embodied energy as well as other energy-using steps were also developed from available data. Total input energy was compared with the energy expected to be made available to end users of the natural gas produced from a typical Marcellus well. The analysis indicates that the EROI of a typical well is likely between 64:1 and 112:1, with a mean of approximately 85:1. This range assumes an estimated ultimate recovery (EUR) of 3.0 billion cubic feet (Bcf) per well. EROI values are directly proportionate to EUR values. If the EUR is greater or lesser than 3 Bcf, the EROI would be proportionately higher or lower. EROI is also sensitive to the energy used or embedded in gathering and transmission pipelines and associated infrastructure and energy used for their construction, energy consumed in well drilling and well completion, and energy used for wastewater treatment.

Analysis of Point-of-Use Energy Return on Investment and Net Energy Yields from China’s Conventional Fossil Fuels

“…It has obviously made a tremendous contribution to China's oil industry and has maintained a long-term stable yield. Compare EROI POU of China's conventional fossil fuels with EROI of unconventional fossil fuels [34][35][36][37][38][39][40][41] from another country, it can be seen that the EROI for China's conventional fossil fuels is lower than the EROI of unconventional fossil fuels based on current literature. Figure 6 also shows the EROI of U.S. shale oil & gas and China's conventional oil & gas.…”

Preliminary Calculation of the EROI for the Production of Gas in Russia

“…(1) Direct energy and material inputs (EROI 1,d ); (2) Direct and indirect energy and material inputs (EROI stnd ); (3) Direct and indirect energy and material inputs and indirect labor consumption (EROI 1,lab ); (4) Direct and indirect energy and material inputs, indirect labor consumption and auxiliary services consumption (EROI 1,aux ); (5) Direct and indirect energy and material inputs, indirect labor consumption, auxiliary services consumption and environmental (EROI 1,env ).…”

“…Because of that, we asked representatives to give the highest possible estimation, by sizing "no more than". For example, the weight of the well casing for each well is 291 t and cement, 250 t. As a comparison, in [5], values were taken as 94-121 t of steel, 170 t of cement.…”

Energy return on investment, energy payback time, and greenhouse gas emissions of coal seam gas (CSG) production in China: a case of the Fanzhuang CSG project

“…Method A has been most widely used by researchers to calculate the EROI of a project or a well (Aucott and Melillo 2013;Dale et al 2013). Using Method A, we can obtain the total EROI of a well because all of the energy inputs are considered, while the change in EROI caused by the depletion of the well (as production increases in a well, more energy is necessary for maintenance and operation to extract the same gas) cannot be observed as easily and clearly.…”