Fractured shale-gas systems
Fractured shale-gas systems
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DOI：
10.1306/61eeddbe-173e-11d7-8645000102c1865d
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发表时间：
2002-11-01
期刊：
影响因子：
3.5
通讯作者：
Curtis, JB
中科院分区：
文献类型：
--
作者：
Curtis, JB
美国第一个商业天然气生产（1821年）来自阿巴拉契亚盆地富含有机物的泥盆纪页岩。自1970年代以来，了解有机页岩地层的地质和地球化学性质并提高其天然气产量一直是价值数百万美元的研究的挑战。页岩气系统本质上是连续型的生物成因（占主导地位）、热成因或生物-热成因复合型天然气藏，其特征是广泛的含气饱和度、隐蔽的圈闭机制、岩性多变的盖层和相对较短的油气运移距离。页岩气可以作为游离气体储存在天然裂缝和粒间孔隙中，作为吸附在油母岩和粘土颗粒表面上的气体，或者作为溶解在油母岩和沥青中的气体。热成熟度（表示为镜质体反射率）、吸附气体分数、储层厚度、总有机碳含量和天然气体积。低基质渗透页岩储层中天然裂缝发育程度是天然气产量的控制因素。到目前为止，只有一小部分页岩威尔斯井，即那些拦截天然裂缝网络的页岩井，能够实现未经刺激的商业生产。在大多数其他情况下，成功的页岩气井需要水力刺激。密歇根盆地的泥盆纪安特里姆页岩和阿巴拉契亚盆地的泥盆纪俄亥俄州页岩加在一起，占1999年页岩气总产量380亿立方英尺的84%。然而，天然气年产量正在稳步增加，来自随后勘探和开发的其他三个主要有机页岩层：伊利诺斯盆地的泥盆纪新奥尔巴尼页岩，沃斯堡盆地的密西西比系巴内特页岩，以及圣胡安盆地的白垩纪刘易斯页岩。在已经进行估计的盆地中，页岩气资源是相当可观的，现有储量为497-783吨立方英尺。估计技术可采资源量（不包括刘易斯页岩）为31至76万亿立方英尺。在这两种情况下，俄亥俄州页岩占最大份额。
The first commercial United States natural gas production (1821) came from an organic-rich Devonian shale in the Appalachian basin. Understanding the geological and geochemical nature of organic shale formations and improving their gas producibility have subsequently been the challenge of millions of dollars worth of research since the 1970s. Shale-gas systems essentially are continuous-type biogenic (predominant), thermogenic, or combined biogenic-thermogenic gas accumulations characterized by widespread gas saturation, subtle trapping mechanisms, seals of variable lithology, and relatively short hydrocarbon migration distances. Shale gas may be stored as free gas in natural fractures and intergranular porosity, as gas sorbed onto kerogen and clay-particle surfaces, or as gas dissolved in kerogen and bitumen.Five United States shale formations that presently produce gas commercially exhibit an unexpectedly wide variation in the values of five key parameters: thermal maturity (expressed as vitrinite reflectance), sorbed-gas fraction, reservoir thickness, total organic carbon content, and volume of gas in place. The degree of natural fracture development in an otherwise low-matrix-permeability shale reservoir is a controlling factor in gas producibility. To date, unstimulated commercial production has been achievable in only a small proportion of shale wells, those that intercept natural fracture networks. In most other cases, a successful shale-gas well requires hydraulic stimulation. Together, the Devonian Antrim Shale of the Michigan basin and Devonian Ohio Shale of the Appalachian basin accounted for about 84% of the total 380 bcf of shale gas produced in 1999. However annual gas production is steadily increasing from three other major organic shale formations that subsequently have been explored and developed: the Devonian New Albany Shalein the Illinois basin, the Mississippian Barnett Shale in the Fort Worth basin, and the Cretaceous Lewis Shale in the San Juan basin.In the basins for which estimates have been made, shale-gas resources are substantial, with in-place volumes of 497-783 tcf. The estimated technically recoverable resource (exclusive of the Lewis Shale) ranges from 31 to 76 tcf. In both cases, the Ohio Shale accounts for the largest share.