CO2 storage and enhanced coalbed methane recovery: Reservoir characterization and fluid flow simulations of the Big George coal,Powder River Basin,Wyoming, USA

Coalbeds are an attractive geological environment for storage of carbon dioxide (CO₂) because CO₂ is retained in the coal as an adsorbed phase and the cost of injection can be offset by enhanced coalbed methane (ECBM) production. This paper presents the findings of a CO₂ storage feasibility study on coalbeds in the Wyodak-Anderson coal zone of the Powder River Basin, Wyoming, USA, using reservoir characterization and fluid flow simulations. A 3D numerical model of the Big George coal was constructed using geostatistical techniques, with values of cleat and matrix permeability and porosity constrained through history-matching of production data from coalbed methane (CBM) wells in the field area.Following history-matching, several ECBM and CO₂ storage scenarios were investigated: shrinkage and swelling of the coal was either allowed or disallowed, a horizontal hydraulic fracture was either placed at the injection well or removed from the model, the number of model layers was varied between 1 and 24, and the permeability and porosity fields were constructed to be either homogeneous or heterogeneous in accordance with geostatistical models of regional variability. All simulations assumed that the injected gas was 100% CO₂ and that the coalbed was overlain by an impermeable caprock. Depending on the scenario, the simulations predicted that after 13 years of CO₂ injection, the cumulative methane production would be enhanced by a factor of 1.5–5. Including coal matrix shrinkage and swelling in the model predicted swelling near the injection well, which resulted in a slight reduction (10%) in injection rate. However, including a horizontal hydraulic fracture in the model at the base of the injection well helped mitigate the negative effect of swelling on injection rate. It was also found that six model layers were needed to have sufficient resolution in the vertical direction to account for the buoyancy effects between the gas and resident water, and that capturing the heterogeneous nature of the coal permeability and porosity fields predicted lower estimates of the storage capacity of the Wyodak-Anderson coal zone.After noting that gravity and buoyancy were the major driving forces behind gas flow within the Big George coal, several leakage scenarios were also investigated, in an effort to better understand the interplay between diffusion and flow properties on the transport and storage of CO₂. The modeling predicted that the upward migration of gas due to the buoyancy effect was faster than the diffusion of CO₂ and therefore the gas rapidly rose to the top of the coalbed and migrated into overlying strata when an impermeable caprock was not included in the model.     

Ready or not: How do we accelerate the developmental readiness of leaders?

A theory of leader developmental readiness is examined comprised of leaders' motivation and ability to develop. Early theory-building and testing suggests leaders' motivation to develop is promoted through interest and goals, learning goal orientation, and developmental efficacy; while leaders' ability to develop is promoted through self-awareness, self-complexity, and meta-cognitive ability. Copyright © 2010 John Wiley & Sons, Ltd.     

A Case Study of Form-Based Solutions for Watershed Protection

Despite an array of policies at the federal and state level aimed at regulating stormwater discharges, engineered solutions enforced by local governments often fall short of meeting water quality standards. Although the implications of land use planning and development regulations are important for stormwater management, they are often overlooked as critical initial steps to improving water quality. This study explores the role of ‘form-based’ regulations as tools for achieving urban planning and water quality objectives. Form-based codes are a new generation of development codes aimed at regulating urban development based on urban form and density, rather than land use. We present an exploratory case study of the feasibility of form-based codes in the Jordan Lake Watershed in North Carolina, a rapidly growing region where fragmented local governments face stringent nutrient reduction standards under new state regulations. Through program analysis and interviews, we explore the viability of form-based codes for reducing development impacts on Jordan Lake’s water quality. We consider the legal feasibility of code enforcement, regional and local barriers and opportunities, and implementation given existing regulatory frameworks. Our findings suggest that high quality information and data modeling are foundational to gaining support for a consensus agreement on the sources and degree of water quality impairment. Furthermore, implementing form-based solutions for water quality is greatly aided by (1) experienced regional planning bodies that have regulatory authority, and (2) local governments whose staff are experienced in implementing complex development ordinances, reviewing architectural renderings, and communicating development requirements with the public and developers.     

Impact of chlorine exposure time on disinfection byproduct formation in the presence of iopamidol and natural organic matter during chloramination

Chloramines,in practice,are formed onsite by adding ammonia to chlorinated drinking water to achieve the required disinfection.While regulated disinfection byproducts(DBPs)are reduced during chloramine disinfection,other DBPs such as iodinated(iodo-)DBPs,that elicit greater toxicity are formed.The objective of this study was to investigate the impact of prechlorination time on the formation of both halogen-specific total organic halogen(TOX)and iodo/chlorinated(chloro-)DBPs during prechlorination/chloramination in source waters(SWs)containing iopamidol,an X-ray contrast medium.Barberton SW(BSW)and Cleveland SW(CSW)containing iopamidol were prechlorinated for 5–60 min and afterwards chloraminated for 72 hr with ammonium chloride.Chlorine contact time(CCT)did not significantly impact total organic iodine(TOI)concentrations after prechlorination or chloramination.Concentrations of total organic chlorine(TOCl)formed during prechlorination did not significantly change regardless of pH and prechlorination time,whileTOClappearedtodecreaseafter 72 hrchloraminationperiod.Dichloroiodomethane(CHCl_2I)formation during prechlorination did not exhibit any significant trends as a function of p H or CCT,but after chloramination,significant increases were observed at pHs 6.5 and 7.5 with respect to CCT.Iodo-HAAs were not formed during prechlorination but were detected after chloramination.Significant quantities of chloroform(CHCl_3)and trichloroacetic acid(TCAA)were formed during prechlorination but formation ceased upon ammonia addition.Therefore,prechlorination studies should measure TOX and DBP concentrations prior to ammonia addition to obtain data regarding the initial conditions.     

Ranch Ownership Change and New Approaches to Water Resource Management in Southwestern Montana: Implications for Fisheries1

Abstract:  This article reports on a survey of ranch owners in high amenity areas in southwestern Montana that have experienced marked ownership change over the last two decades. Specifically, we focus on findings from a set of questions targeting water resource and riparian area management. After reviewing the results, we consider how new owners may be managing water resources differently than longtime owners and what the ecological implications of this shift in management might be for Montana’s prized wild fisheries. Uses more closely associated with new owners than with longtime owners include water reallocation to instream uses, aquatic and riparian ecosystem restoration, and fish pond construction. These uses have both positive and negative impacts on the region’s fisheries. Our findings suggest that current laws and institutions guiding the management of water resources and the aquatic and riparian ecosystems they support may not be adequate to address emerging conservation opportunities and challenges.