Abstract

Western Australia’s Canning Basin is an underexplored prospective basin with proven petroleum systems and small-scale production. Recently, several formations within deeper depocentres have been investigated for unconventional hydrocarbon resources. Modern petroleum resource evaluation generally depends on an understanding of local and regional stresses that are a primary control over the formation and propagation of induced fractures. There are significant gaps in our understanding of these factors within the Canning Basin. This study characterises the regional stress regime of the onshore Canning Basin and presents modelled present-day stress, allowing for the identification of significant stress heterogeneity and natural fracture barriers. Interpretation of wireline data reveals a present-day state of stress with variation in magnitude and faulting-type. An approximately northeast–southwest regional present-day maximum horizontal stress orientation is interpreted, which is in broad agreement with the Australian Stress Map and previously published data. One-dimensional mechanical earth models, constructed for intervals from 15 Canning Basin wells, highlight the relationship between lithology and stress. Significant changes in stress within and between lithological units, owing to the existence of discrete mechanical units forming numerous inter- and intra-formational stress boundaries, likely to act as natural barriers to fracture propagation, particularly within those units currently targeted for their unconventional resource potential, are interpreted. A strike-slip faulting stress regime is interpreted broadly through the basin. However, when analysed in detail there are three distinct stress zones identified: (1) a transitional reverse- to strike-slip faulting stress regime in the top ∼1 km, (2) a strike-slip faulting stress regime from ∼1 km to ∼3.0 km and (3) a transitional strike-slip to normal faulting regime at depths greater than ∼3.0 km. This study is a component of the Australian Government’s Exploring for the Future initiative, which focusses on gathering new data and information about northern Australia’s resource potential.

1. KEY POINTS

2. New stress data, including 15 mechanical earth models, are presented for Western Australia’s onshore Canning Basin.

3. Broadly, a strike-slip stress regime with a NE–SW-oriented maximum horizontal orientation is described.

4. Significant stress heterogeneities and natural fracture barriers are identified.

摘要

西澳大利亚州的坎宁盆地是一个未充分开发的远景盆地，拥有成熟的石油系统和小规模生产。最近，已经对更深沉积中心内的几个地层进行了非常规油气资源的调查。现代石油资源评价通常取决于对局部和区域应力的理解，这些应力是诱导裂缝形成和扩展的主要控制因素。我们对坎宁盆地内这些因素的理解存在重大差距。这项研究描述了陆上坎宁盆地的区域应力状态，并呈现了模拟的当今应力，从而可以识别出显着的应力异质性和天然裂缝障碍。对电缆数据的解释揭示了当前的应力状态，其大小和断层类型都发生了变化。解释了大约东北-西南区域的当今最大水平应力方向，这与澳大利亚应力图和先前发布的数据大体一致。为 Canning Basin 15 口井的层段构建的一维机械地球模型突出了岩性与应力之间的关系。岩性单元内部和之间的应力发生显着变化，因为存在离散的机械单元，形成许多地层间和地层内应力边界，可能成为裂缝扩展的天然屏障，特别是在目前以非常规资源潜力为目标的单元中, 被解释。整个盆地的走滑断层应力状态被广泛解释。然而，当详细分析时，确定了三个不同的应力带：（1）顶部约 1 公里处的反向到走滑断层的过渡应力状态，（2）约 1 公里到走滑断层的应力状态。约 3.0 公里和（3）在深度大于约 3.0 公里处向正常断层区过渡的走滑。这项研究是澳大利亚政府探索未来计划的一个组成部分，该计划的重点是收集有关澳大利亚北部资源潜力的新数据和信息。(2) 约 1 公里至约 3.0 公里的走滑断层应力制度和 (3) 深度大于约 3.0 公里的走滑过渡到正常断层制度。这项研究是澳大利亚政府探索未来计划的一个组成部分，该计划的重点是收集有关澳大利亚北部资源潜力的新数据和信息。(2) 约 1 公里至约 3.0 公里的走滑断层应力制度和 (3) 深度大于约 3.0 公里的走滑过渡到正常断层制度。这项研究是澳大利亚政府探索未来计划的一个组成部分，该计划的重点是收集有关澳大利亚北部资源潜力的新数据和信息。

1. 关键点

2. 提供了西澳大利亚陆上坎宁盆地的新应力数据，包括 15 个机械地球模型。

3. 从广义上讲，描述了具有 NE-SW 方向的最大水平方向的走滑应力状态。

4. 确定了显着的应力异质性和天然裂缝障碍。