北美西部内陆海盆Niobrara组的钙质超微化石及其环境意义Ⅱ:古环境研究

沉积于北美西部白垩纪内陆海盆的Niobrara组 ,是一套以白垩 ,白垩质灰岩 ,以及钙质页岩为主的海相沉积 ,其中白垩的主要组分为颗石藻及其它钙质超微化石。通过对Kansas州西部和SouthDakota州东部四条剖面中Niobrara组的岩性 ,沉积物厚度 ,及钙质超微化石的研究 ,证明北美西部内陆海盆的沉积环境及水体温度在Niobrara组沉积时期因地而异。在Niobrara组沉积初期 ,海盆内的水体温度为北冷南暖 ,其后 ,至少在位于Kansas西部海域的海水温度呈与时逐渐降低趋势。钙质超微化石有关属种在盆地内的分布差异 。

北美西部内陆海盆Niobrara组的钙质超微化石及其环境意义Ⅰ:钙质超微化石及其分带

北美西部内陆海盆上白垩统Niobrara组中的钙质超微化石十分丰富 ,且多保存良好 ,呈现典型的晚白垩世远洋钙质超微化石组合面貌 ,经系统鉴定 ,计有 6 0属 10 0余种和亚种。为适应不同的环境 ,Kansas西部和SouthDakota东部的钙质超微化石组合面貌稍有不同。经与白垩纪颗石藻化石带对比 ,可将Kansas西部的Niobrara组划分为 6个化石带 (CC13～CC18)和 8个亚带 ,其中 ,根据本文研究地区的化石序列 ,CC15和CC16带被进一步划分。根据与同一剖面所建立的无脊椎动物化石带对比 ,钙质超微化石CC17带的时代被重新厘定 ,即该带应始于中Santonian的晚期 ,结束于晚Santonian的早期 。

非常规储层岩石特征研究——Bakken组、Eagle Ford组和Niobrara组储层对比

富含流体的页岩储层对美国油气产量贡献极大。页岩储层所在的的Bakken组、Eagle Ford组和Niobrara组储层在矿物组成、孔隙结构、有机质含量及流体组成等方面均不相同。要开发好这些地层的油气资源,关键在于区分、鉴别各储层的地质特征,而且,掌握各储层的地质特征对于油气井的增产设计、水力压裂也是非常有利的。为了搞清楚微观储层特征对流体流动的影响,

Improved Water Use Estimates for Drilling and Hydrualic Fracturing in Northeastern Colorado

The development of unconventional resources in tight shales has stimulated considerable growth of oil and gas production in Northeastern Colorado, but has led to concerns about added demands on the region’s strained water resources. Northeastern Colorado’s semi-arid environment, population growth, competing water demands and uncertainty about drilling and hydraulic fracturing water requirements have resulted in scrutiny and conflict surrounding water use for tight shales. This study collects water use data from wells in Northeastern Colorado to improve water estimates and to better understand important contributing factors. Most water resource studies use estimates for the number of future wells to predict water demands. This study shows that the number of hydraulic fracturing stages is a better measure of the future water demands for horizontal wells. Vertical wells use significantly less water than horizontal wells and will be less prevalent in the future.

Timing of Onset of Volcanic Centers in the Campanian of Western North America as Determined by Distal Ashfalls

Strata of the Late Cretaceous Niobrara Formation and Pierre Shale Group include bentonites that provide a distal record of volcanic activity taking place to the west. Detailed stratigraphic analysis combined with mineralogy and geochemistry of the bentonites indicates the following timing of events: 1) Eustatic sea level fall as a result of the end of the Niobrara Cycle;2) Tectonic deformation of the Western Interior Seaway coincident with tectonism on the Absoroka Thrust in Wyoming and Late Canyon Range Thrust in Utah;3) Backarc volcanism in Montana associated with the Little Elkhorn Mountain volcanic complex;4) Forearc volcanism in the Cascades area indicates subduction of a hot oceanic crust where plagioclase in the oceanic crust is being incorporated into the melt;5) Cessation of tectonic activity results in a return of sedimentation patterns to north-south trending belts with the Boyer Bay and Burning Brule members of the Sharon Springs Formation deposited to the east and the Mitten Black Shale Formation deposited in the basin.

Petrophysical Tutorial, Lessons Learned, and Evaluation Workflow: A Case Study in the Power River Basin

The objective is to empower the reader and scientific community with the knowledge and specific applicable equations to then reproduce the critical rock and fluid attributes in the Powder River Basin. To then continue to unravel the basin and its potential (both conventionally and unconventionally). The overall goal is to ensure the transfer of knowledge and communication of a petrophysical workflow that can then also influence application to other basins worldwide. The Powder River Basin is in southeast Montana and northeast Wyoming and is a prolific oil and gas (hydrocarbon-prone) sedimentary basin related to the greater Rockies chain/series of hydrocarbon-bearing basins (ex. Big Horn, Greater Green River, Denver-Jules). In this study, we briefly set-up the geological background of the Powder River Basin and the importance/ relevance to then tackling subsurface petrophysical evaluation on a regional scale. Approximately, 200 wells were evaluated petrophysically by a combined deterministic and inversion-based workflow representing an effort to share best practices, approaches, and the relative trends to apply in the basin to unravel the stratigraphic hydrocarbon potential in place. An extensive workflow involving basic petrophysical approaches such as raw log applicable cutoffs and volume of clay determination are shared as well as extending knowledge and application into advanced petrophysics through geochemical property derivation and impact of those derived properties as well as bound versus free water and hydrocarbon understanding. Results of the petrophysical analysis highlight the varying properties in conventional and unconventional formations (example Niobrara). The results of how and why the petrophysical approach was calibrated and then applied are the primary efforts accomplished.

美国鹰滩和尼奥泊拉拉页岩油富集主控因素

页岩油已经成为石油勘探开发的一个新领域，运用综合地质研究的方法,以揭示页岩油成藏条件为目的，对美国白垩系鹰滩和尼奥泊拉拉页岩的特征进行分析。研究认为，控制页岩油富集高产的主要地质因素包括：页岩富含有机质，TOC 一般大于 2%；成熟度适中，Ro以 0.75%～1.10%为宜；储层厚度较大，微孔发育；岩石脆性好，易于体积压裂；构造稳定，埋藏适中，保存条件好；另外，最好发育天然裂缝。对页岩油成藏特征的研究揭示了其形成的特殊性,对国内页岩油的勘探开发有一定指导意义。

微井眼连续管钻井概念应用于成熟气田

由于美国Niobrara组的油田多为高孔、低渗、低压储层，因此需要使用高效低成本的钻完井方法。最近，美国能源部正在进行微井眼连续管技术研究，希望通过研发钻889mm或更小尺寸井眼的工具和技术，使边际油气藏的开发成为可能。油田试验在西堪萨斯和东科罗拉多进行，使用ADT公司的连续管钻机，取得了单日钻进945m、节约成本30％、减少储层损害等效果。