库车坳陷断层控制下的盐岩塑性流动及对上覆地层构造影响的沙箱模拟

SANDBOX SIMULATION OF SALTROCK PLASTIC FLOW CONTROLLED BY FAULTS IN THE KUCHE DEPRESSION OF THE TARIM BASIN AND ITS INFLUENCE ON OVERLYING STRATIGRAPHIC STRUCTURES

王子煜

WANG Zi-yu

石油大学, 油气成藏机理教育部重点实验室, 北京, 102249

Petroleum Accumuation Mechanism Key Labortory of Education Department, University of Petroleum, Beijing 102249, China

以塔里木盆地库车坳陷北秋背斜为模拟的实际构造样式,采集新生界岩石样品和盐岩样品,并测定样品的岩石力学参数(弹性模量、泊松比、抗压强度等).通过理论计算和实验,根据相似性原理,选择凡士林和松散的细沙为实验材料.采用双侧挤压模型,对断层控制下的盐岩塑性流动及其对上覆地层构造的影响进行沙箱模拟.实验结果表明:a)库车坳陷北秋背斜型的构造样式是由于下伏盐岩在断层控制下塑性流动而形成的,盐岩的塑性流动和上覆盖层构造的形成与构造作用的时间和速率关系密切,快速、短时间作用下表现为脆性,缓慢、长时间作用下表现为塑性;b)断层边界产状是控制盐岩流动方向的主要因素之一;c)盐岩厚度变化受塑性流动和构造作用共同影响,盐岩内部存在复杂的构造变形;d)盐-岩相互作用并不完全协调,边界有"脱空"现象;e)下伏岩层的岩石力学性质影响和控制着上覆岩层构造的发育,尽管上覆地层的岩石力学性质可能是一致的.

Taking the Beiqiu Anticline in the Kuche Depression of the Tarim Basin as the actual structural style of the simulation experiment,the Cenozoic rock and saltrock were sampled and analysed for lithomechanical parameters (i.e.,elastic modulus,Poisson's ratio,compressive strength,etc.). By theoretical calculation and experiment,vaseline and loose fine sand were chosen as experimental material based on the similarity principle. Using the bilateral-compressive model. the saltrock plastic flow controlled by faults and its influence on overlying stratigraphic structures were simulated in a sandbox. The results revealed that a) the structural style of the Beiqiu Anticline type in the Kuche Depression was formed by underlying saltrock plastic flow under the control of faults,and the plastic flow of saltrock and the formation of overlying caprock structures were closely related to the time and velocity of tectonic processess,displaying brittle in the rapid and short-time process or plastic in the slow and long-time process;b)the boundary occurrence of faults was one of the major factors controlling the direction of saltrock flow;c) the change of saltrock thickness was jointly affected by plastic flow and tectonic processes,and complex structure deformation existed within the inner of saltrock;d) the salt-rock interaction was not well coordinated,and the "disjunctive" appearance was shown in the boundary;and e) the lithomechanical properties of underlying rock layers affected and controlled the development of overlying rock structures,though the overlying strata may have the identical lithomechanical properties.

国家"973"重大科技攻关项目(G1999043305).

https://doi.org/10.11781/sysydz200205441