Light hydrocarbon geochemistry:insight into oils/condensates families and inferred source rocks of the Woodford–Mississippian tight oil play in North-Central Oklahoma,USA

The Woodford–Mississippian"Commingled Production"is a prolific unconventional hydrocarbon play in Oklahoma,USA.The tight reservoirs feature variations in produced fluid chemistry usually explained by different possible source rocks.Such chemical variations are regularly obtained from bulk,molecular,and isotopic characteristics.In this study,we present a new geochemical investigation of gasoline range hydrocarbons,biomarkers,and diamondoids in oils from Mississippian carbonate and Woodford Shale.A set of oil/condensate samples were examined using high-performance gas chromatography and mass spectrometry.The result of the condensates from the Anadarko Basin shows a distinct geochemical fingerprint reflected in light hydrocarbon characterized by heptane star diagrams,convinced by biomarker characteristics and diamantane isomeric distributions.Two possible source rocks were identified,the Woodford Shale and Mississippian mudrocks,with a variable degree of mixing.Thermal maturity based on light hydrocarbon parameters indicates that condensates from the Anadarko Basin are of the highest maturity,followed by"Old"Woodford-sourced oils and central Oklahoma tight oils.These geochemical parameters shed light on petroleum migration within Devonian–Mississippian petroleum systems and mitigate geological risk in exploring and developing petroleum reservoirs.

Deep resistivity "turnover" effect at oil generation "peak" in the Woodford Shale,Anadarko Basin,USA

The Devonian Woodford Shale in the Anadarko Basin is a highly organic,hydrocarbon source rock.Accurate values of vitrinite reflectance(R_o)present in the Woodford Shale penetrated by 52 control wells were measured directly.These vitrinite reflectance values,when plotted against borehole resistivity for the middle member of the Woodford Shale in the wells,display a rarely reported finding that deep resistivity readings decrease as R_o increases when R_o is greater than 0.90%.This phenomenon may be attributed to that aromatic and resin compounds containing conjugated pi bonds generated within source rocks are more electrically conductive than aliphatic compounds.And aromatic and resin fractions were generated more than aliphatic fraction when source rock maturity further increases beyond oil peak.The finding of the relationship between deep resistivity and R_o may re-investigate the previously found linear relationship between source rock formation and aid to unconventional play exploration.

美国俄克拉荷马州伍德福德页岩甜点控制因素研究

美国俄克拉荷马州伍德福德（Woodford）页岩区带是美国近年来新兴起的重要的非常规页岩油气生产区之一,其覆盖区域包括阿纳达科（Anadarko）盆地、阿德莫（Ardmore）盆地、阿卡马（Arkoma）盆地和切罗基（Cherokee）台地。伍德福德页岩是北美重要的泥盆系富含有机质页岩,有机质含量最高可达14%。伍德福德页岩甜点区域位于凝析气或成熟油窗,页岩的镜质组反射率（Ro）为0.6%~1.4%,岩层厚度超过20 m;底部必须具有厚度至少15 m以上的隔层,以防止压裂串通上下含水层;具有有机质含量高达7%的岩层和燧石层等脆性夹层,裂缝发育程度高,钻井位置必须避开大型断裂。根据甜点控制因素,设计具有针对性的钻完井方案,降低钻探风险和成本,可以获取较高的开发效益。

致密油/凝析油中的轻烃地球化学特征——以美国伍德福德-密西西比油气区带为例

密西西比(Mississippian)石灰岩致密储层特征的变化反映了所产油气化学性质的不同,这通常被解释为油气可能来源于不同的烃源岩。文中对产自密西西比石灰岩和伍德福德(Woodford)页岩致密储层中的原油样品的轻烃、分子标志物进行了气相色谱(GC)和气相色谱-质谱(GC-MS)测试。结果显示:源自密西西比石灰岩的原油具有独特的地球化学指纹特征,如丰富的长链三环萜烷和独特的庚烷星图展布特征,这些特征指示了有机质来源和热成熟度等信息;原油分子组成特征的差异揭示了可能有2套烃源岩层,分别是伍德福德页岩和密西西比石灰岩。该研究为阿纳达科盆地泥盆系-密西西比系油气系统中的油气运移提供了地球化学方面的证据和启示,减小了勘探开发的地质风险。

Significance of Shale Gas Development

Natural gas production from shale formations is growing exponentially in the United States. This paper introduces the five major shale formations in the United States and the technologies used to produce them. The Barnett, Haynesville, Fayetteville, Woodford, and Marcellus combined hold an estimated 978 trillion cubic feet of total gas reserves. These findings along with recent technological advances in horizontal drilling and completion methods have transformed the natural gas exploration and production industry in the U.S. and have fundamentally changed the U.S. energy picture. Specifically this paper states that the United States through the utilization of natural gas from shale can reduce its carbon emissions and can become more energy self-sufficient. Finally, the Harding & Shelton Group states in this paper that the opportunity to locate and produce shale gas in China is very similar to that which has taken place in the United States.

以调解社会隔阂为目标的城市设计理念探索——以伦敦某居住社区为例

伦敦是一座世界顶级的国际大都市,也是一座多元化的文化熔炉,居民来自世界各地,其种族、宗教、文化背景各异,他们共同居住在这座城市中,其生活水平与社会地位也不尽相同,比起真正意义上的融合,实际上不同社会背景的人们都有着其特定的分布和领域,互相之间出现了空间分隔的状态。该文以一处实际的居住社区为案例,从当地的特点出发,提出改善其现存状态的概念设计方案,以促进两个被分隔社区的互动,保证居住空间的宜人氛围和健康发展。