The Eagle Ford Outcrops of West Texas: A Laboratory for Understanding Heterogeneities within Unconventional Mudstone Reservoirs
The Eagle Ford Outcrops of West Texas: A Laboratory for Understanding Heterogeneities within Unconventional Mudstone Reservoirs
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西德克萨斯州伊格尔福特露头：了解非常规泥岩储层异质性的实验室
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发表时间：
2012
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通讯作者：
R. Gardner
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作者：
A. Donovan;T. S. Staerker;A. Pramudito;Weiguo Li;M. Corbett;C. Lowery;A. Romero;R. Gardner
西得克萨斯州的Eagle福特露头提供了一个独特的机会，可以检查相当于南得克萨斯州Eagle福特非常规泥岩储层的地层，其具有良好的垂直和横向连续暴露。尽管非常规泥岩储层通常被描述为均质的，但我们迄今的工作揭示了鹰福特群中的垂直非均质相和总有机碳（TOC）序列，在地层、准层序、层序和层序集尺度上存在变异性。这种非均质性表明，非常规储层中可能存在明显的垂直变化，这将影响油井动态。理解和预测这些变化对于在地下有效地布置水平井至关重要。西德克萨斯州鹰福特群的露头由五个不同相的垂直序列组成，每个相包含一个亚相的垂直序列。利用这些相和亚相将伊格尔福特群划分为下伊格尔福特组和上伊格尔福特组。在下伊格尔福特组中，定义了一个（下部）未命名的成员和（上部）中页岩成员，而在上伊格尔福特组中，提出了一个（下部）未命名的成员和（上部）朗特里成员。四个鹰福特成员，这可以从得克萨斯州西部的露头到得克萨斯州南部的地下相关联，具有独特的岩性特征，地球化学特征，地理分布和年代地层学意义。由于鹰福特群内的四个岩石地层段以区域可制图的不整合面为界，因此它们也是年代地层单位，（1）彼此不同生，（2）下伏的布达石灰岩，或（3）上覆的奥斯汀白垩。162 Copyright © 2012.墨西哥湾沿岸地质学会协会。All rights reserved. 2012年3月13日收到手稿; 2012年6月27日收到修订稿; 2012年7月25日接受手稿。GCAGS Journal，v. 1（2012），p. 162-185.墨西哥湾沿岸地质学会联合会的出版物
The Eagle Ford outcrops in West Texas provide a unique opportunity to examine strata equivalent to the Eagle Ford unconventional mudstone reservoirs of South Texas in excellent vertically and laterally continuous exposures. Whereas unconventional mudstone reservoirs are commonly portrayed as homogenous, our work to date reveals a vertically heterogeneous facies and total-organic-carbon (TOC) succession in the Eagle Ford Group, with variability at the bed-, parasequence-, sequence-, and sequence-set scale. This heterogeneity suggests the potential for distinct vertical variability in the unconventional reservoirs that would affect well performance. Understanding and predicting those variations is essential to enable effective horizontal-well placement in the subsurface. Outcrops of the Eagle Ford Group in West Texas consist of a vertical succession of five distinct facies, each of which contains a vertical succession of sub-facies. These facies and sub-facies were used to divide the Eagle Ford Group into the Lower Eagle Ford Formation and Upper Eagle Ford Formation. Within the Lower Eagle Ford Formation a (lower) unnamed member and (upper) Middle Shale Member were defined, whereas in the Upper Eagle Ford Formation a (lower) unnamed member and the (upper) Langtry Member are proposed. Each of the four Eagle Ford members, which can be correlated from the outcrops of West Texas into the subsurface of South Texas, have distinct lithologic characteristics, geochemical signatures, geographic distributions, and chronostratigraphic significance. Because the four proposed lithostratigraphic members within the Eagle Ford Group are bounded by regionally mappable unconformities, they are also chronostratigraphic units that are not coeval to (1) each other, (2) the underlying Buda Limestone, or (3) the overlying Austin Chalk. 162 Copyright © 2012. Gulf Coast Association of Geological Societies. All rights reserved. Manuscript received March 13, 2012; revised manuscript received June 27, 2012; manuscript accepted July 25, 2012. GCAGS Journal, v. 1 (2012), p. 162–185. A Publication of the Gulf Coast Association of Geological Societies