Heterogeneity in grainstone reservoirs - Investigation of a modern analog, Joulters Cays, Bahamas
Heterogeneity in grainstone reservoirs - Investigation of a modern analog, Joulters Cays, Bahamas
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粒岩储层的非均质性 - 现代模拟的研究，乔尔特斯珊瑚礁，巴哈马
DOI：
10.1306/44b4acc1-170a-11d7-8645000102c1865d
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
G. W. V. Stoep
中科院分区：
文献类型：
--
作者：
D. Bebout;M. H. Holtz;C. Kerans;R. Major;D. Ratcliff;N. Tyler;G. W. V. Stoep
Skeleton.球粒状和卵粒状颗粒岩形成全世界烃类的主要碳酸盐储层。二叠纪盆地的圣安德烈斯和格雷堡地层的储层提供了这种储层类型的极好例子。地下和露头研究记录了这些基础内发生的变浅循环的薄颗粒岩单元内的极端渗透率变化。朱尔特斯礁卵状浅滩位于大巴哈马浅滩的安德罗斯岛北部，是迄今为止记录最完整的现代碳酸盐砂复合体。但是，即使在Joulters，以前研究的岩心间距大约是每平方英里一个岩心，这并不接近解决大多数井间非均质性问题所需的水平。利用现有的区域岩心框架作为指导，进行了详细的取心程序，井距接近成熟油藏（20 - 40 ac/井），以检查活动浅滩的一些亚环境内的沉积物变化和早期成岩作用。在Joulters采集的岩心和盒状岩心主要是干净的卵砾石砂（粒屑岩）和少量的泥质砂（泥质砂岩）。然而，在整个浅滩的沉积风格的变化和这些变化对保存的结构的影响是特别重要的。树脂通过boxmore岩心渗透的变化表明，与粒度的微小变化相关的渗透率差异较大。这些差异在浅滩向岸一侧的溢流瓣交叉分层的分级单元内最为明显。斜层状向海倾单元变化较小。范围至少为1 m{sup 2}的胶结带（硬地）也可能导致渗透率的不均匀性。这些类型的微妙的沉积和早期成岩组构影响随后的成岩作用和由此产生的渗透率变化的颗粒砂岩储层。«少
Skeletal. peloidal, and ooid grainstones form major carbonate reservoirs for hydrocarbons throughout the world. Reservoirs in the San Andres and Grayburg formations of the Permian basin provide excellent examples of this reservoir type. Subsurface and outcrop studies have documented extreme permeability variability within thin grainstone units of shoallng cycles that occur within these foundations. The Joulters Cays ooid shoal, located north of Andros Island, Great Bahamas Bank, is the most thoroughly documented modern carbonate sand complex. But even at Joulters, the core spacing of previous studies was approximately one core per square mile, which does not approach the sc le needed to address most problems of interwell heterogeneity. Using the existing regional core framework as a guide, a detailed coring program with well spacing approximating that in mature oil reservoirs (between 20 and 40 ac/well) was undertaken to examine the sediment variation and early diagenesis within some subenvironments of the active shoal. Cores and box cores taken at Joulters are dominantly clean ooid sands (grainstones) with minor muddy sands (packstone). However, changes in depositional style across the shoal and the effect of these changes on the preserved texture are of particular significance. Variations in the penetration of resin through boxmore » cores suggest greater permeability differences that are related to minor changes in grain size. These differences are most evident within graded units of spillover-lobe cross stratification on the bankward side of the shoal. Parallel-laminated seaward-dipping units show less variation. Cemented zones (hardgrounds), ranging up to at least 1 m{sup 2} in extent, also may contribute to the permeability heterogeneity. These types of subtle depositional and early diagenetic fabrics influence subsequent diagenesis and resultant permeability variations in grainstone reservoirs.« less