Mechanisms in CO2-enhanced coalbed methane recovery process

Injection of CO2 and subsequent desorption of CH4 is considered to be the most efficient enhanced coalbed methane (ECBM) recovery technique to date. Meanwhile, CO2-ECBM is an excellent option for CO2 geo-sequestration for an extended period. Despite ongoing research efforts and several field applications of this technology, the mechanisms of the process have yet to be fully understood. The coalbed heterogeneity, the fluid interactions with coal, the CO2 induced swelling, and the continuous pressure and composition changes require outright insights for optimal application of the technique. Furthermore, intermolecular interactions of CO2 and CH4, their competitive adsorption on the dry/wet coal surface, and the dispersion and advection processes play an important role in defining the CO2-ECBM recovery process. An attempt has been made here to understand the key mechanisms of CO2-ECBM recovery in coalfields, particularly the adsorption of CO2 in the supercritical state at the recommended sequestration depth.Cited as: Asif, M., Wang, L., Wang, R., Wang, H., Hazlett, R. D. Mechanisms in CO2-enhanced coalbed methane recovery process. Advances in Geo-Energy Research, 2022, 6(6): x-x. https://doi.org/10.46690/ager.2022.06.0

ADVANCES IN CRYOGENIC FRACTURING OF COALBED METHANE RESERVOIRS WITH LN2

Coalbed methane (CBM) is a significant unconventional natural gas resource existing in matrix pores and fractures of coal seams and is a cleaner energy resource compared to coal and crude oil. To produce CBM, stimulation operations are required, given that the coal permeability is generally too low. Hydraulic fracturing is the most widely used technology for reservoir stimulation; however, there are a few challenging issues associated with it, e.g., huge water consumption. In the past decade, the use of liquid nitrogen (LN2) as a fracturing fluid has been intensively studied for stimulating CBM reservoirs, achieving considerable progress in understanding fracturing mechanisms and optimizing fracturing techniques. This paper presents a thorough review of experimental design and observations, modeling procedures and results, field applications, and published patents. Existing studies are divided into five different groups for discussion and comparison, including immersion tests, injection tests, jet drilling tests, numerical modeling, and field applications. Based on the comprehensive evaluation of the outcomes, it is obvious that cryogenic fracturing using LN2 is a promising eco-friendly fracturing technique that can effectively enhance coal rock permeability to increase the production of CBM

Simulation of residual oil displacement in a sinusoidal channel with the lattice Boltzmann method

We simulate oil slug displacement in a sinusoidal channel in order to validate computational models and algorithms for multi-component flow. This case fits in the gap between fully realistic cases characterized by complicated geometry and academic cases with simplistic geometry. Our computational model is based on the lattice Boltzmann method and allows for variation of physical parameters such as wettability and viscosity. The effect of variation of model parameters is analyzed, in particular via comparison with analytical solutions. We discuss the requirements for accurate solution of the oil slug displacement problem.Comment: Comptes Rendus Mecanique 201

Economic and Safety Considerations: Motor Vehicle Safety Inspections for Passenger Vehicles in Texas

The objective of this study was to meet legislative needs inquiring about the efficiency and necessity of titling and inspection of vehicles in the state of Texas. This was accomplished through three tasks: quantifying the efficiency of the vehicle inspection program; assessing the safety impact of eliminating the inspection program; and making recommendations on whether the inspection program should be eliminated as an element of vehicle titling. The University of Texas at Austin\u2019s Center for Transportation Research (CTR) conducted a literature review, public opinion survey, and examination of state inspection databases in order to perform the assessments on the economic and safety impacts of eliminating the inspection program. CTR found that average crash costs related to vehicles with defects are more than $2 billion per year, where most defects are vehicle elements which would fail an inspection. CTR also found that if the inspection program were discontinued, station owners would lose net revenue of over$131 million per year, the State of Texas would lose revenue of approximately $150 million per year, and vehicle owners would save approximately$16 per vehicle per year, for a collective savings of $307 million. The public opinion survey showed that the majority (68.6%) of Texas drivers polled believe that the inspection program improves highway safety in Texas. Given the results of the analysis, CTR strongly recommends that the inspection program be retained and that another study be conducted to determine whether additional inspection items should be included in the inspection program

Evaluating Safety and Economic Impacts of Texas Travel Information Centers

Senate Bill 1, passed in 2017 during the 85th Legislature Regular Session, contained Rider 32. This bill requires the Texas Department of Transportation (TxDOT) to publish a report by November 1, 2018, describing the economic and safety impacts of travel information centers (TICs). TICs are believed to have positive impacts on travelers\u2019 safety. However, not all of the safety benefits have been identified or quantified in Texas. The purpose of this study is to develop a systematic approach to identify and quantify the impacts of Texas TICs on highway safety. TxDOT\u2019s Travel Information Division (TRV) contracted with the University of Texas at Austin\u2019s Center for Transportation Research (CTR) to conduct this study. This study had the following objectives: Assess the impact of TICs on Texas highway safety by providing travel information and safety messages. Compare the safety impact of TICs and non-staffed safety rest areas. Analyze the economic impact of TICs in terms of promoting tourism. Determine whether TICs and their employees play a positive role in improving Texas highway safety; Make recommendations based on study findings. The study team anticipates that this report will provide the State Legislature and the public a better understanding of TIC safety benefits

Mother-infant interactions and regional brain volumes in infancy: an MRI study

Background: It is generally agreed that the human brain is responsive to environmental influences, and that the male brain may be particularly sensitive to early adversity. However, this is largely based on retrospective studies of older children and adolescents exposed to extreme environments in childhood. Less is understood about how normative variations in parent-child interactions are associated with the development of the infant brain in typical settings. Method: To address this, we used magnetic resonance imaging to investigate the relationship between observational measures of mother-infant interactions and regional brain volumes in a community sample of 3-6 month old infants (N=39). In addition, we examined whether this relationship differed in male and female infants. Results: We found that lower maternal sensitivity was correlated with smaller subcortical grey matter volumes in the whole sample, and that this was similar in both sexes. However, male infants who showed greater levels of positive communication and engagement during early interactions had smaller cerebellar volumes. Conclusion These preliminary findings suggest that variations in mother-infant interaction dimensions are associated with differences in infant brain development. Although the study is cross-sectional and causation cannot be inferred, the findings reveal a dynamic interaction between brain and environment that may be important when considering interventions to optimize infant outcomes

Advances in Cryogenic Fracturing of Coalbed Methane Reservoirs with LN2

Coalbed methane (CBM) is a significant unconventional natural gas resource existing in matrix pores and fractures of coal seams and is a cleaner energy resource compared to coal and crude oil. To produce CBM, stimulation operations are required, given that the coal permeability is generally too low. Hydraulic fracturing is the most widely used technology for reservoir stimulation; however, there are a few challenging issues associated with it, e.g., huge water consumption. In the past decade, the use of liquid nitrogen (LN2) as a fracturing fluid has been intensively studied for stimulating CBM reservoirs, achieving considerable progress in understanding fracturing mechanisms and optimizing fracturing techniques. This paper presents a thorough review of experimental design and observations, modeling procedures and results, field applications, and published patents. Existing studies are divided into five different groups for discussion and comparison, including immersion tests, injection tests, jet drilling tests, numerical modeling, and field applications. Based on the comprehensive evaluation of the outcomes, it is obvious that cryogenic fracturing using LN2 is a promising eco-friendly fracturing technique that can effectively enhance coal rock permeability to increase the production of CBM