页岩气开发对植被和土壤的影响研究进展

页岩气开发和生产过程影响水资源与水质、土地利用与植被覆盖、土壤侵蚀与土壤质量。综述了页岩气开发和生产过程可能存在的生态环境影响,并重点评价了国际上不同区域页岩气开发和生产对土地利用和植被覆被变化、景观破碎化的影响,以及对土壤侵蚀和土壤质量的影响。研究发现页岩气开发平台、运输道路和管线占用农田、牧场、森林,造成不同程度的景观破碎化,在坡地开发页岩气会导致土壤侵蚀与沉积风险增大。截止2015年末,在我国重庆涪陵焦石坝页岩气产建区55.8%的面积(146.56 km~2)存在土壤侵蚀和石漠化生态风险。我国页岩气开发区水基钻屑固化填埋未对周边土壤造成污染。建议页岩气开发设计应考虑占地、景观破碎化的影响,并及时开展页岩气开发暂时占地的复垦工作。     

油田硫酸盐还原菌酸化腐蚀机制及防治研究进展

硫酸盐还原菌(Sulfate reducing bacteria,SRB)是一些厌氧产硫化氢的细菌的统称,是以有机物为养料的厌氧菌。它们广泛分布于pH值6-9的土壤、海水、河水、淤泥、地下管道、油气井、港湾及锈层中,它们生存于好气性硫细菌产生的沉积物下,其最适宜的生长温度是20-30℃,可以在高达50-60℃的温度下生存,与腐蚀相关的最主要的是脱硫脱硫弧菌(Desulfovibrio desulfuricans)。 它们是许多腐蚀问题的主因,例如油田系统金属管路的腐蚀等。在海上油田生产中,海水常被注入油井用于进行2次采油。富含硫酸盐的海水能加速油藏中SRB的生长,随之H₂S大量产生,引起油田水的酸化,H₂S具有毒性和腐蚀性,增加石油和天然气中的硫含量,并可能引起油田堵塞。SRB引起的腐蚀问题是拭待解决的最主要问题。国内外治理该问题的途径主要有物理杀灭、添加化学杀菌剂等方法,但是这些方法成本高,持续效果不显著。近几年来国外学者开始重点关注利用生物竞争排斥技术(Bio-competitive inhibition technology,BCX)控制硫酸盐还原菌的生长代谢的方法,该方法的原理为通过加入特定的药剂,激活油藏中的本源微生物或加入外源微生物,使其与SRB竞争营养源或产生代谢物抑制SRB的生长代谢,进而抑制H₂S的产生。GMT-LATA的科学家对在厌氧油气储层和开采系统中硝酸盐还原菌的作用进行了最早的研究,认为该细菌可以抑制硫酸盐还原菌的代谢活动。随后BCX技术已经在国外部分油田得到了应用,国内还没有在海油生产中应用的报道,但是也有学者对该方法进行了研究。     

Oil and gas development in the World Heritage and wider protected area network in sub-Saharan Africa

More than 25% of natural World Heritage (WH) sites worldwide are estimated to be under pressure from existing or future mining and energy activities (IUCN 2008; UNESCO 2009). However, that ‘pressure’ has yet to be quantitatively defined and assessed for many regions of the world. We conducted a GIS-based analysis of overlap and proximity between natural WH sites and areas allocated to oil and gas concessions as well as pipelines and oil wells for all of sub-Saharan Africa. We found that oil and gas concessions were located within 27% of the WH sites, though no currently active oil wells were operating directly within the WH sites. A proximity-based assessment of oil and gas concessions within 5 km of WH site boundaries included only one additional WH site, suggesting that sites susceptible to indirect impacts from oil and gas development are likely to be those already overlapped by concessions. Our findings indicate that activity from oil and gas development in sub-Saharan WH sites has to date been limited; however, future pressure cannot be ruled out, due to continued presence of concessions within more than one quarter of the network, and projected expansion of oil and gas exploration within the region. Our results may be used to inform the inclusion of new sites into the WH network.     

A system to evaluate the scientific quality of biological and restoration objectives using National Wildlife Refuge Comprehensive Conservation Plans as a case study

It is widely accepted that plans for restoration projects should contain specific, measurable, and science-based objectives to guide restoration efforts. The United States Fish and Wildlife Service (USFWS) is in the process of developing Comprehensive Conservation Plans (CCPs) for more than 500 units in the National Wildlife Refuge System (NWRS). These plans contain objectives for biological and ecosystem restoration efforts on the refuges. Based on USFWS policy, a system was developed to evaluate the scientific quality of such objectives based on three critical factors: (1) Is the objective specific, measurable, achievable, results-oriented, and time-fixed? (2) What is the extent of the rationale that explains the assumptions, logic, and reasoning for the objective? (3) How well was available science used in the development of the objective? The evaluation system scores each factor on a scale of 1 (poor) to 4 (excellent) according to detailed criteria. The biological and restoration objectives from CCPs published as of September 2004 (60 total) were evaluated. The overall average score for all biological and restoration objectives was 1.73. Average scores for each factor were: Factor 1–1.97; Factor 2–1.86; Factor 3–1.38. The overall scores increased from 1997 to 2004. Future restoration efforts may benefit by using this evaluation system during the process of plan development, to ensure that biological and restoration objectives are of the highest scientific quality possible prior to the implementation of restoration plans, and to allow for improved monitoring and adaptive management.     

Disturbance factors influencing greater sage-grouse lek abandonment in north-central Wyoming

Detecting the disappearance of active leks is the most efficient way to determine large declines in greater sage-grouse (Centrocercus urophasianus) populations; thus, understanding factors that influence lek abandonment is critical. We evaluated factors that may have influenced the probability of sage-grouse lek abandonment in the Bighorn Basin (BHB) of north-central Wyoming from 1980 to 2009. Our objective was to examine lek abandonment based on landscape characteristics that explain differences between occupied and unoccupied leks. We evaluated lek abandonment from 144 occupied and 39 unoccupied leks from the Wyoming Game and Fish Department lek database with sufficient data for our 30-year analysis. We conducted our analysis with binary logistic regression using landscape predictor variables obtained from geographic coverages at 5 scales (1.0-, 3.2-, 4.0-, 5.0-, and 6.4-km radii around leks) to evaluate how these disturbances have influenced lek abandonment. Coverages included anthropogenic characteristics such as agricultural development, oil and gas development, prescribed burned treatments, and roads; and environmental characteristics such as vegetation attributes and wildfire. Our combined model included the number of oil and gas wells in a 1.0-km radius, percent area of wildfire in a 1.0-km radius, and variability in shrub height in a 1.0-km radius around sage-grouse leks. Abandoned (unoccupied) leks had 1.1-times the variability of shrub height in a 1.0-km radius, 3.1-times the percentage of wildfire in a 1.0-km radius, and 10.3-times the number of oil and gas wells in a 1.0-km radius compared to occupied leks. The model-averaged odds of lek persistence with every 1 unit increase in oil and gas wells within a 1.0-km radius was 0.66 (90% CI: 0.37–0.94), odds with every 1% increase in wildfire in a 1.0-km radius was 0.99 (90% CI: 0.85–1.12), and odds with every 1 unit increase in the standard deviation of shrub height within a 1.0-km radius around a lek was 0.77 (90% CI: 0.45–1.08). Because the 90% confidence intervals around the odds ratios of wells did not overlap 1.0, we suggest this predictor variable was most influential in our model-averaged estimates. The BHB has lower developed reserves of oil and gas than many other regions; however, our study supports findings from other studies that demonstrate energy development increases lek abandonment. Our findings indicate conservation efforts should be focused on minimizing well development and implementing wildfire suppression tactics near active sage-grouse leks. © 2012 The Wildlife Society.     

Microbiological and production characteristics of the high-temperature Kongdian petroleum reservoir revealed during field trial of biotechnology for the enhancement of oil recovery

Microbiological technology for the enhancement of oil recovery based on the activation of the stratal microflora was tested in the high-temperature horizons of the Kongdian bed (60°C) of the Dagang oil-field (China). This biotechnology consists in the pumping of a water-air mixture and nitrogen and phosphorus mineral salts into the oil stratum through injection wells in order to stimulate the activity of the stratal microflora which produce oil-releasing metabolites. Monitoring of the physicochemical, microbiological, and production characteristics of the trial site has revealed large changes in the ecosystem as a result of the application of biotechnology. The cell numbers of thermophilic hydrocarbon-oxidizing, fermentative, sulfate-reducing, and methanogenic microorganisms increased 10–10000-fold. The rates of methanogenesis and sulfate reduction increased in the near-bottom zone of the injection wells and of some production wells. The microbial oil transformation was accompanied by the accumulation of bicarbonate ions, volatile fatty acids, and biosurfactants in the formation waters, as well as of CH₄ and CO₂ both in the gas phase and in the oil. Microbial metabolites promoted the additional recovery of oil. As a result of the application of biotechnology, the water content in the production liquid from the trial site decreased, and the oil content increased. This allowed the recovery of more than 14000 tons of additional oil over 3.5 years.     

In Situ Biosurfactant Production by Bacillus Strains Injected into a Limestone Petroleum Reservoir

Biosurfactant-mediated oil recovery may be an economic approach for recovery of significant amounts of oil entrapped in reservoirs, but evidence that biosurfactants can be produced in situ at concentrations needed to mobilize oil is lacking. We tested whether two Bacillus strains that produce lipopeptide biosurfactants can metabolize and produce their biosurfactants in an oil reservoir. Five wells that produce from the same Viola limestone formation were used. Two wells received an inoculum (a mixture of Bacillus strain RS-1 and Bacillus subtilis subsp. spizizenii NRRL B-23049) and nutrients (glucose, sodium nitrate, and trace metals), two wells received just nutrients, and one well received only formation water. Results showed in situ metabolism and biosurfactant production. The average concentration of lipopeptide biosurfactant in the produced fluids of the inoculated wells was about 90 mg/liter. This concentration is approximately nine times the minimum concentration required to mobilize entrapped oil from sandstone cores. Carbon dioxide, acetate, lactate, ethanol, and 2,3-butanediol were detected in the produced fluids of the inoculated wells. Only CO₂ and ethanol were detected in the produced fluids of the nutrient-only-treated wells. Microbiological and molecular data showed that the microorganisms injected into the formation were retrieved in the produced fluids of the inoculated wells. We provide essential data for modeling microbial oil recovery processes in situ, including growth rates (0.06 ± 0.01 h⁻¹), carbon balances (107% ± 34%), biosurfactant production rates (0.02 ± 0.001 h⁻¹), and biosurfactant yields (0.015 ± 0.001 mol biosurfactant/mol glucose). The data demonstrate the technical feasibility of microbial processes for oil recovery.     

Numerical Simulation of Abandoned Gob Methane Drainage through Surface Vertical Wells

The influence of the ventilation system on the abandoned gob weakens, so the gas seepage characteristics in the abandoned gob are significantly different from those in a normal mining gob. In connection with this, this study physically simulated the movement of overlying rock strata. A spatial distribution function for gob permeability was derived. A numerical model using FLUENT for abandoned gob methane drainage through surface wells was established, and the derived spatial distribution function for gob permeability was imported into the numerical model. The control range of surface wells, flow patterns and distribution rules for static pressure in the abandoned gob under different well locations were determined using the calculated results from the numerical model.     

Degradative capacities and 16S rRNA-targeted whole-cell hybridization of sulfate-reducing bacteria in an anaerobic enrichment culture utilizing alkylbenzenes from crude oil.

A mesophilic sulfate-reducing enrichment culture growing anaerobically on crude oil was used as a model system to study which nutritional types of sulfate-reducing bacteria may develop on original petroleum constituents in oil wells, tanks, and pipelines. Chemical analysis of oil hydrocarbons during growth revealed depletion of toluene and o-xylene within 1 month and of m-xylene, o-ethyltoluene, m-ethyltoluene, m-propyltoluene, and m-isopropyltoluene within approximately 2 months. In anaerobic counting series, the highest numbers of CFU (6 x 10(6) to 8 x 10(6) CFU ml-1) were obtained with toluene and benzoate. Almost the same numbers were obtained with lactate, a substrate often used for detection of the vibrio-shaped, incompletely oxidizing Desulfovibrio sp. In the present study, however, lactate yielded mostly colonies of oval to rod-shaped, completely oxidizing, sulfate-reducing bacteria which were able to grow slowly on toluene or crude oil. Desulfovibrio species were detected only at low numbers (3 x 10(5) CFU ml-1). In agreement with this finding, a fluorescently labeled, 16S rRNA-targeted oligonucleotide probe described in the literature as specific for members of the Desulfovibrionaceae (suggested family) hybridized only with a small portion (< 5%) of the cells in the enrichment culture. These results are consistent with the observation that known Desulfovibrio species do not utilize aromatic hydrocarbons, the predominant substrates in the enrichment culture. All known sulfate-reducing bacteria which utilize aromatic compounds belong to a separate branch, the Desulfobacteriaceae (suggested family). Most members of this family are complete oxidizers. For specific hybridization with members of this branch, the probe had to be modified by a nucleotide exchange. Indeed, this modified probe hybridized with more than 95% of the cells in the enrichment culture. The results show that completely oxidizing, alkylbenzene-utilizing sulfate-reducing bacteria rather than Desulfovibrio species have to be considered in attempts to understand the microbiology of sulfide production in oil wells, tanks, and pipelines when no electron donors other than the indigenous oil constituents are available.     

A Primer on the Offshore Contract Drilling Industry

Mobile offshore drilling units (MODUs) are specialized marine vessels used to drill subsea wells to find and produce hydrocarbons. The contract drilling industry is critical to the offshore oil and gas supply chain, and market dynamics are an important factor in the costs to drill an offshore well. In this article, an introduction to the industry is provided with an emphasis on the factors that influence rig day rates and market structure.     

Microbiological and production characteristics of the high-temperature Kongdian bed revealed during field trial of biotechnology for the enhancement of oil recovery

Microbiological technology for the enhancement of oil recovery based on the activation of the stratal microflora was tested in the high-temperature horizons of the Kongdian bed (60 degrees C) of the Dagang oil field (China). This biotechnology consists in the pumping of a water-air mixture and nitrogen and phosphorus mineral salts into the oil stratum through injection wells in order to stimulate the activity of the stratal microflora which produce oil-releasing metabolites. Monitoring of the physicochemical, microbiological, and production characteristics of the test site has revealed large changes in the ecosystem as a result of the application of biotechnology. The cell numbers of thermophilic hydrocarbon-oxidizing, fermentative, sulfate-reducing, and methanogenic microorganisms increased 10-10 000-fold. The rates of methanogenesis and sulfate reduction increased in the near-bottom zone of the injection wells and of some production wells. The microbial oil transformation was accompanied by the accumulation of bicarbonate ions, volatile fatty acids, and biosurfactants in the formation waters, as well as of CH4 and CO2 both in the gas phase and in the oil. Microbial metabolites promoted the additional recovery of oil. As a result of the application of biotechnology, the water content in the production liquid from the test site decreased, and the oil content increased. This allowed the recovery of more than 14000 tons of additional oil over 3.5 years.     

Enhancing the Farm Bill's Conservation Potential Through Land Prioritization

ABSTRACT The Farm Bill conservation programs serve as the primary tools for the creation and improvement of wildlife habitat on working lands. Wildlife conservation would benefit from a working land-prioritization system that integrates these programs. We developed a Geographic Information System (GIS)–based system to prioritize land for inclusion in Farm Bill conservation programs. We designed the system to be applicable throughout the United States, to minimize potential conflicts of interest, and to facilitate simple implementation. We designated high conservation value (HCV) lands using habitats of greatest conservation need. We placed priority zones around HCV lands to determine high- and low-priority working lands. Nationwide implementation of this system would require gathering and manipulating data from multiple sources, as well as creation of a GIS layer denoting locations of working lands currently in conservation programs. This system would allow funding to be maximized through the ability to select participation based on property location and size, and to target landowners for participation. The wide-ranging potential benefits of this system make it well-suited for serving as the backbone to conservation on working lands.     

基于机器学习模型的沙漠腹地地下水含盐量变化过程及模拟研究

为了研究塔克拉玛干沙漠腹地的地下水盐分变化规律,模拟地下水盐分变化过程,评价适合该区域的地下水变化规律的模型。通过对研究区蒸发量、降水量、气温、气压、地下水位、地下水电导率数据的统计分析,揭示了地下水含盐量及其影响因素的特征;使用GP模型、GPLVM模型和BP人工神经网络模型以及综合模型,模拟了气候变化和人类活动双重影响下的地下水含盐量变化过程,并评价了模型的模拟结果。研究结果表明:(1)研究区地下水流动系统主要受气候变化和人类活动的影响,地下水位在局部地区随开采过程呈现波动变化。地下水位变化过程与气压的变化规律相一致;而气温和蒸发量的季节变化规律相一致。地下水盐分含量呈上升趋势。(2)GP模型对于地下水含盐量的预测效果最好;GPLVM模型对于已知地下水含盐量条件下,与其他环境因素进行多元回归分析的拟合效果最好。而GP、GPLVM和BP人工神经网络模型的综合模型,对于包括模型训练和模型预测的全体数据集的拟合和预测效果最好。     

Diversity of Microbial Communities in Production and Injection Waters of Algerian Oilfields Revealed by 16S rRNA Gene Amplicon 454 Pyrosequencing

The microorganisms inhabiting many petroleum reservoirs are multi-extremophiles capable of surviving in environments with high temperature, pressure and salinity. Their activity influences oil quality and they are an important reservoir of enzymes of industrial interest. To study these microbial assemblages and to assess any modifications that may be caused by industrial practices, the bacterial and archaeal communities in waters from four Algerian oilfields were described and compared. Three different types of samples were analyzed: production waters from flooded wells, production waters from non-flooded wells and injection waters used for flooding (water-bearing formations). Microbial communities of production and injection waters appeared to be significantly different. From a quantitative point of view, injection waters harbored roughly ten times more microbial cells than production waters. Bacteria dominated in injection waters, while Archaea dominated in production waters. Statistical analysis based on the relative abundance and bacterial community composition (BCC) revealed significant differences between production and injection waters at both OTUs_0.03 and phylum level. However, no significant difference was found between production waters from flooded and non-flooded wells, suggesting that most of the microorganisms introduced by the injection waters were unable to survive in the production waters. Furthermore, a Venn diagram generated to compare the BCC of production and injection waters of one flooded well revealed only 4% of shared bacterial OTUs. Phylogenetic analysis of bacterial sequences indicated that Alpha-, Beta- and Gammaproteobacteria were the main classes in most of the water samples. Archaeal sequences were only obtained from production wells and each well had a unique archaeal community composition, mainly belonging to Methanobacteria, Methanomicrobia, Thermoprotei and Halobacteria classes. Many of the bacterial genera retrieved had already been reported as degraders of complex organic molecules and pollutants. Nevertheless, a large number of unclassified bacterial and archaeal sequences were found in the analyzed samples, indicating that subsurface waters in oilfields could harbor new and still-non-described microbial species.     

Recent Land Use Change to Agriculture in the U.S. Lake States: Impacts on Cellulosic Biomass Potential and Natural Lands

Perennial cellulosic feedstocks may have potential to reduce life-cycle greenhouse gas (GHG) emissions by offsetting fossil fuels. However, this potential depends on meeting a number of important criteria involving land cover change, including avoiding displacement of agricultural production, not reducing uncultivated natural lands that provide biodiversity habitat and other valued ecosystem services, and avoiding the carbon debt (the amount of time needed to repay the initial carbon loss) that accompanies displacing natural lands. It is unclear whether recent agricultural expansion in the United States competes with lands potentially suited for bioenergy feedstocks. Here, we evaluate how recent land cover change (2008–2013) has affected the availability of lands potentially suited for bioenergy feedstock production in the U.S. Lake States (Minnesota, Wisconsin, Michigan) and its impact on other natural ecosystems. The region is potentially well suited for a diversity of bioenergy production systems, both grasses and woody biomass, due to the widespread forest economy in the north and agricultural economy in the south. Based on remotely-sensed data, our results show that between 2008 and 2013, 836,000 ha of non-agricultural open lands were already converted to agricultural uses in the Lake States, a loss of nearly 37%. The greatest relative changes occurred in the southern half that includes some of the most diverse cultivable lands in the country. We use transition diagrams to reveal gross changes that can be obscured if only net change is considered. Our results indicate that expansion of row crops (corn, soybean) was responsible for the majority of open land loss. Even if recently lost open lands were brought into perennial feedstock production, there would a substantial carbon debt. This reduction in open land availability for biomass production is closing the window of opportunity to establish a sustainable cellulosic feedstock economy in the Lake States as mandated by current Federal policy, incurring a substantial GHG debt, and displacing a range of other natural ecosystems and their services.     

Influence of Well Pad Activity on Winter Habitat Selection Patterns of Mule Deer

ABSTRACT Conversion of native winter range into producing gas fields can affect the habitat selection and distribution patterns of mule deer (Odocoileus hemionus). Understanding how levels of human activity influence mule deer is necessary to evaluate mitigation measures and reduce indirect habitat loss to mule deer on winter ranges with natural gas development. We examined how 3 types of well pads with varying levels of vehicle traffic influenced mule deer habitat selection in western Wyoming during the winters of 2005–2006 and 2006–2007. Well pad types included producing wells without a liquids gathering system (LGS), producing wells with a LGS, and well pads with active directional drilling. We used 36,699 Global Positioning System locations collected from a sample (n = 31) of adult (>1.5-yr-old) female mule deer to model probability of use as a function of traffic level and other habitat covariates. We treated each deer as the experimental unit and developed a population-level resource selection function for each winter by averaging coefficients among models for individual deer. Model coefficients and predictive maps for both winters suggested that mule deer avoided all types of well pads and selected areas further from well pads with high levels of traffic. Accordingly, impacts to mule deer could probably be reduced through technology and planning that minimizes the number of well pads and amount of human activity associated with them. Our results suggested that indirect habitat loss may be reduced by approximately 38–63% when condensate and produced water are collected in LGS pipelines rather than stored at well pads and removed via tanker trucks. The LGS seemed to reduce long-term (i.e., production phase) indirect habitat loss to wintering mule deer, whereas drilling in crucial winter range created a short-term (i.e., drilling phase) increase in deer disturbance and indirect habitat loss. Recognizing how mule deer respond to different types of well pads and traffic regimes may improve the ability of agencies and industry to estimate cumulative effects and quantify indirect habitat losses associated with different development scenarios.     

混合菌系QZ-10对原油的作用性能表征及现场清防蜡应用

[背景]油藏环境中呈单相液态的原油,在开采、运送的过程中由于温度、压力及流动条件的变化,石蜡不断从原油中析出,造成井筒、管线的结蜡.微生物清防蜡作为一项新兴的技术,受到广泛的关注,但是需要根据现场的环境条件施用合适的微生物清防蜡菌液.[目的]利用来源于青海油田盐碱油藏环境的混合菌系QZ-10,有效解决油井结蜡的问题并探...     

Soil properties and C dynamics in abandoned and cultivated farmlands in a semi-arid ecosystem

Background and Aims

Land abandonment might be an alternative management for restoring soil conditions and C from prolonged cultivation and agricultural practices. In the present study, the influence of 18–22?years of land abandonment on soil properties, C dynamics and microbial biomass was evaluated in closely situated wheat and alfalfa farmlands, and abandoned lands on calcareous soils, Central Iran.

Methods

Soil properties of the 0–15 and 15–30?cm depths from abandoned lands were compared to those from conventionally cultivated lands (i.e., continuous wheat–fallow and alfalfa–wheat rotation) common in calcareous soils of Central Zagros Mountains.

Results

Soil bulk density in the 0–15 and 15–30?cm layers decreased significantly while total porosity increased significantly in abandoned lands. Generally, soil aggregate stability tended to increase within the abandoned fields owing to increased water-stable macro-aggregates. Soil organic C (OC) contents (g kg^?1) and pools (Mg ha^?1) in the 0–15?cm soil layer increased significantly in abandoned lands compared with cultivated lands, with no effect in the 15–30?cm soil layer after 18–22?years of land abandonment, suggesting the restoration of C is pronounced in the upper 0–15?cm soil depth . The total C accumulation in abandoned lands was 7.0?Mg?C?ha^?1 for the entire sampling depth (0–30?cm) over the 18–22?years of land abandonment, which was 26% greater relative to cultivated lands. Carbon mineralization (Cmin) followed a trend similar to organic C, whereas C turnover (Cmin/OC ratio) was slightly greater in wheat fields. However, soil microbial biomass C (MBC) did not vary considerably among the three land uses.

Conclusions

In brief, improvements, albeit slowly, in soil properties of the top layer with the cessation of cultivation indicated that land abandonment may result in enhanced soil C sequestration, and would maintain fertility and productivity of the farmlands of semi-arid climates.     

Bacterial Communities Associated with Production Facilities of Two Newly Drilled Thermogenic Natural Gas Wells in the Barnett Shale (Texas, USA)

We monitored the bacterial communities in the gas–water separator and water storage tank of two newly drilled natural gas wells in the Barnett Shale in north central Texas, using a 16S rRNA gene pyrosequencing approach over a period of 6?months. Overall, the communities were composed mainly of moderately halophilic and halotolerant members of the phyla Firmicutes and Proteobacteria (classes Βeta-, Gamma-, and Epsilonproteobacteria) in both wells at all sampling times and locations. Many of the observed lineages were encountered in prior investigations of microbial communities from various fossil fluid formations and production facilities. In all of the samples, multiple H₂S-producing lineages were encountered; belonging to the sulfate- and sulfur-reducing class Deltaproteobacteria, order Clostridiales, and phylum Synergistetes, as well as the thiosulfate-reducing order Halanaerobiales. The bacterial communities from the separator and tank samples bore little resemblance to the bacterial communities in the drilling mud and hydraulic-fracture waters that were used to drill these wells, suggesting the in situ development of the unique bacterial communities in such well components was in response to the prevalent geochemical conditions present. Conversely, comparison of the bacterial communities on temporal and spatial scales suggested the establishment of a core microbial community in each sampled location. The results provide the first overview of bacterial dynamics and colonization patterns in newly drilled, thermogenic natural gas wells and highlights patterns of spatial and temporal variability observed in bacterial communities in natural gas production facilities.     

Mapping Oil and Gas Development Potential in the US Intermountain West and Estimating Impacts to Species

Background

Many studies have quantified the indirect effect of hydrocarbon-based economies on climate change and biodiversity, concluding that a significant proportion of species will be threatened with extinction. However, few studies have measured the direct effect of new energy production infrastructure on species persistence.

Methodology/Principal Findings

We propose a systematic way to forecast patterns of future energy development and calculate impacts to species using spatially-explicit predictive modeling techniques to estimate oil and gas potential and create development build-out scenarios by seeding the landscape with oil and gas wells based on underlying potential. We illustrate our approach for the greater sage-grouse (Centrocercus urophasianus) in the western US and translate the build-out scenarios into estimated impacts on sage-grouse. We project that future oil and gas development will cause a 7–19 percent decline from 2007 sage-grouse lek population counts and impact 3.7 million ha of sagebrush shrublands and 1.1 million ha of grasslands in the study area.

Conclusions/Significance

Maps of where oil and gas development is anticipated in the US Intermountain West can be used by decision-makers intent on minimizing impacts to sage-grouse. This analysis also provides a general framework for using predictive models and build-out scenarios to anticipate impacts to species. These predictive models and build-out scenarios allow tradeoffs to be considered between species conservation and energy development prior to implementation.