scholarly journals Quantifying methane emissions from natural gas production in northeastern Pennsylvania

Author(s):  
Zachary R. Barkley ◽  
Thomas Lauvaux ◽  
Kenneth J. Davis ◽  
Aijun Deng ◽  
Yanni Cao ◽  
...  

Abstract. Natural gas infrastructure releases methane (CH4), a potent greenhouse gas, into the atmosphere. The estimated emission rate associated with the production and transportation of natural gas is uncertain, hindering our understanding of its greenhouse footprint. This study presents a new application of inverse methodology for estimating regional emission rates from natural gas production and gathering facilities in northeastern Pennsylvania. An inventory of CH4 emissions was compiled for major sources in Pennsylvania. This inventory served as input emission data for the Weather Research and Forecasting model with chemistry enabled, and atmospheric CH4 mole fraction fields were generated at 3 km resolution. Simulated atmospheric CH4 enhancements from WRF-Chem were compared to observations obtained from a three-week flight campaign in May 2015. Modelled enhancements from sources not associated with upstream natural gas processes were assumed constant and known and therefore removed from the optimization procedure, creating a set of observed enhancements from natural gas only. Simulated emission rates from unconventional production were then adjusted to minimize the mismatch between aircraft observations and model-simulated mole fractions for ten flights. To evaluate the method, an aircraft mass balance calculation was performed for four flights where conditions permitted its use. Using the model optimization approach, the weighted mean emission rate from unconventional natural gas production and gathering facilities in northeastern Pennsylvania approach is found to be 0.36 % of total gas production, with a 2σ confidence interval between 0.27–0.45 % of production. Similarly, the mean emission estimates using the aircraft mass balance approach is calculated to be 0.34 % of regional natural gas production, with a 2σ confidence interval between 0.06–0.62 % of production. These emission rates as a percent of production are lower than rates found in any other basin using a top-down methodology, and may be indicative of some characteristics of the basin that makes sources from the northeastern Marcellus region unique.

2017 ◽  
Vol 17 (22) ◽  
pp. 13941-13966 ◽  
Author(s):  
Zachary R. Barkley ◽  
Thomas Lauvaux ◽  
Kenneth J. Davis ◽  
Aijun Deng ◽  
Natasha L. Miles ◽  
...  

Abstract. Natural gas infrastructure releases methane (CH4), a potent greenhouse gas, into the atmosphere. The estimated emission rate associated with the production and transportation of natural gas is uncertain, hindering our understanding of its greenhouse footprint. This study presents a new application of inverse methodology for estimating regional emission rates from natural gas production and gathering facilities in north-eastern Pennsylvania. An inventory of CH4 emissions was compiled for major sources in Pennsylvania. This inventory served as input emission data for the Weather Research and Forecasting model with chemistry enabled (WRF-Chem), and atmospheric CH4 mole fraction fields were generated at 3 km resolution. Simulated atmospheric CH4 enhancements from WRF-Chem were compared to observations obtained from a 3-week flight campaign in May 2015. Modelled enhancements from sources not associated with upstream natural gas processes were assumed constant and known and therefore removed from the optimization procedure, creating a set of observed enhancements from natural gas only. Simulated emission rates from unconventional production were then adjusted to minimize the mismatch between aircraft observations and model-simulated mole fractions for 10 flights. To evaluate the method, an aircraft mass balance calculation was performed for four flights where conditions permitted its use. Using the model optimization approach, the weighted mean emission rate from unconventional natural gas production and gathering facilities in north-eastern Pennsylvania approach is found to be 0.36 % of total gas production, with a 2σ confidence interval between 0.27 and 0.45 % of production. Similarly, the mean emission estimates using the aircraft mass balance approach are calculated to be 0.40 % of regional natural gas production, with a 2σ confidence interval between 0.08 and 0.72 % of production. These emission rates as a percent of production are lower than rates found in any other basin using a top-down methodology, and may be indicative of some characteristics of the basin that make sources from the north-eastern Marcellus region unique.


2018 ◽  
Vol 115 (46) ◽  
pp. 11712-11717 ◽  
Author(s):  
Timothy L. Vaughn ◽  
Clay S. Bell ◽  
Cody K. Pickering ◽  
Stefan Schwietzke ◽  
Garvin A. Heath ◽  
...  

This study spatially and temporally aligns top-down and bottom-up methane emission estimates for a natural gas production basin, using multiscale emission measurements and detailed activity data reporting. We show that episodic venting from manual liquid unloadings, which occur at a small fraction of natural gas well pads, drives a factor-of-two temporal variation in the basin-scale emission rate of a US dry shale gas play. The midafternoon peak emission rate aligns with the sampling time of all regional aircraft emission studies, which target well-mixed boundary layer conditions present in the afternoon. A mechanistic understanding of emission estimates derived from various methods is critical for unbiased emission verification and effective greenhouse gas emission mitigation. Our results demonstrate that direct comparison of emission estimates from methods covering widely different timescales can be misleading.


Author(s):  
Guo Yu ◽  
Haitao Li ◽  
Yanru Chen ◽  
Linqing Liu ◽  
Chenyu Wang ◽  
...  

AbstractQuantifying natural gas production risk can help guide natural gas exploration and development in Carboniferous gas reservoirs. In this study, the Monte Carlo probability method is used to obtain the probability distribution and growth curve of each production risk factor and production in a Carboniferous gas reservoir in eastern Sichuan. In addition, the fuzzy comprehensive evaluation method is used to conduct the sensitivity analysis of the risk factors, and the natural gas production and realization probability under different risk factors are obtained. The research results show that: (1) the risk factor–production growth curve and probability distribution are calculated by the Monte Carlo probability method. The average annual production under the stable production stage under different realization probabilities is obtained. The maximum probability range of annual production is $$\left( {43.43 - 126.35} \right) \times 10^{8} {\text{m}}^{3} /{\text{year}}$$ 43.43 - 126.35 × 10 8 m 3 / year , and the probability range is 14.59–92.88%. (2) The risk factor sensitivity analysis is significantly affected by the probability interval. In the entire probability interval, the more sensitive risk factors are the average production of the kilometer-deep well (D) and the production rate in the stable production stage (A). During the exploration and development of natural gas, these two risk factors can be adjusted to increase production.


2000 ◽  
Vol 41 (10-11) ◽  
pp. 117-123 ◽  
Author(s):  
C. Visvanathan ◽  
P. Svenstrup ◽  
P. Ariyamethee

This paper presents a case study of a natural gas production site covering various technical issues related to selection of an appropriate Reverse Osmosis (RO) system. The long-term field experience indicates the necessity of the selection of appropriate pretreatment systems for fouling-free RO operational conditions. The produced water has a variety of impurities such as oil and grease, process chemicals used for corrosion and scaling control, and dehydration of natural gas, etc. This situation leads to a complicated and extremely difficult task for a membrane specialist to design RO systems, especially the pre-treatment section. Here as part of the pretreatment selection, two types of UF membrane modules viz. spiral wound and hollow fibre, with MWCO of 8000 and 50,000 Dalton respectively, were tested in parallel with NF membranes of the spiral wound type with MWCO 200 Dalton. The UF permeate is used as feed for RO compatibility testing. Both configurations of UF failed to be compatible, due to irreversible fouling of the RO membrane. The NF membrane, however, showed interesting results, due to membrane stability in terms of cleaning and fouling. The NF plant with 50% capacity gave a recovery of 75% and the RO plant gave a recovery of 60% versus the expected 92–95%. The long-term tests have indicated that the reminder of the membranes could be installed to achieve full capacity of the plant. This study also demonstrates the importance of selection of proper pre-treatment set-up for the RO system design.


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