Discovery of the Breagh gas field in the Southern North Sea (SNS) has demonstrated the potential that the Lower Carboniferous (Visean, 346.7–330.9 Ma) Farne Group reservoirs have to contribute to the UK's future energy mix. New biostratigraphic correlations provide a basis to compare Asbian and Brigantian sedimentary cores from the Breagh Field and age-equivalent sediments exposed on the Northumberland Coast, which has proved critical in gaining an understanding of exploration and development opportunities. Thirteen facies associations characterize the mixed carbonate–siliciclastic system, grouped into: marine, delta front, delta shoreface, lower delta plain and upper delta plain gross depositional environments. The facies associations are interpreted as depositing in a mixed carbonate and siliciclastic fluvio-deltaic environment, and are arranged into coarsening- and cleaning-upward cycles (parasequences) bounded by flooding surfaces. Most cycles are characterized by mouth bars, distributary channels, interdistributary bays and common braided rivers, interpreted as river-dominated deltaic deposits. Some cycles include rare shoreface and tidally-influenced deposits, interpreted as river-dominated and wave- or tide-influenced deltaic deposits. The depositional processes that formed each cycle have important implications for the reservoir net/gross ratio (where this ratio indicates the proportion of sandstone beds in a cycle), thickness and lateral extent. The deltaic deposits were controlled by a combination of tectonic and eustatic (allocyclic) events and delta avulsion (autocyclic) processes, and are likely to reflect a changing tectonic regime, from extension within elongate fault-bounded basins (synrift) to passive regional thermal subsidence (post-rift). Deep incision by the Base Permian Unconformity across the Breagh Field has removed the Westphalian, Namurian and upper Visean, to leave the more prospective thicker clastic reservoirs within closure. Thematic collection: This article is part of the Under-explored plays and frontier basins of the UK continental shelf collection available at: https://www.lyellcollection.org/cc/under-explored-plays-and-frontier-basins-of-the-uk-continental-shelf

中文翻译：

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英格兰东北部和北海南部下石炭纪（Visean）混合碳酸盐-硅质碎屑沉积的沉积和构造控制：对储层结构的影响

在北海南部 (SNS) 发现 Breagh 气田已经证明了下石炭统（Visean，346.7-330.9 Ma）Farne Group 储层必须为英国未来的能源结构做出贡献的潜力。新的生物地层相关性为比较来自 Breagh 油田的 Asbian 和 Brigantian 沉积岩心与暴露在诺森伯兰海岸的同龄沉积物提供了基础，事实证明，这对于了解勘探和开发机会至关重要。13 个相组合表征了混合碳酸盐-硅质碎屑系统，分为：海相、三角洲前缘、三角洲岸面、下三角洲平原和上三角洲平原总沉积环境。相组合被解释为沉积在混合碳酸盐和硅质碎屑河三角洲环境中，并被排列成以泛滥表面为边界的粗化和向上清洁循环（准序列）。大多数旋回的特征是河口坝、分流河道、分流间海湾和常见的辫状河，被解释为以河流为主的三角洲沉积物。一些循环包括罕见的岸面和受潮汐影响的沉积物，解释为河流主导和波浪或潮汐影响的三角洲沉积物。形成每个旋回的沉积过程对储层净/总比（该比表示旋回中砂岩层的比例）、厚度和横向范围具有重要意义。三角洲沉积物受构造和恒常（异环）事件以及三角洲剥脱（自旋）过程的控制，并且很可能反映了不断变化的构造制度，从伸长的断层盆地（同裂谷）内的延伸到被动区域热沉降（裂谷后）。横跨 Breagh 油田的二叠纪底部不整合面的深切已经移除了威斯特伐利亚、纳穆里亚和上维森，从而使更有前景的更厚碎屑岩储层处于封闭状态。专题收藏：本文是英国大陆架收藏的未开发区和边境盆地的一部分，可从以下网址获取：https://www.lyellcollection.org/cc/under-explored-plays-and-frontier-basins-of -英国大陆架