东沙岛西南泥火山区的地震烃类检测

近年来通过多道地震、浅剖及海底采样调查在东沙岛西南海域发现了大量喷溢甲烷的泥火山,通过研究泥火山可能会发现含气层,具有重大的油气资源指示意义.一条多道地震剖面显示,在该海域一泥火山MV3附近存在一个具有极性反转的埋藏背斜构造,其振幅绝对值随偏移距增大而增大.为探究该背斜是否含有烃类气体,开展了速度分析、AVO反演和频率...     

利用航磁数据识别浅覆盖区地质体的方法研究

在浅覆盖区,常规填图方法填制的地质图,由于信息量少导致整体质量不高.利用勘查技术方法来提高覆盖区地质填图的效率、质量和地质研究水平,具有重要的现实意义.航磁方法是其中的一种重要方法,但航磁测量获取的数据是磁异常迭加的综合反应,而区域地质填图仅描述地表附近的地质情况,直接利用航磁数据辅助地质填图是不合理的.因此,基于插值切割、数理统计和灰色关联度分析等方法,提出了一种剔除深部影响,利用浅层岩石磁性分布规律和磁性差异来识别浅覆盖区地质体的新思路.经选用黑龙江省塔河地区数据进行验证,识别效果明显.     

Influence of Layered Structures of the Seabed on the Formation of Gas Hydrates in the Area Surrounding Deep-Sea Mud Volcanoes: A Mathematical Model

Doklady Earth Sciences - The evolutionary processes of gas hydrate accumulations associated with deep-sea mud volcanoes are discussed. A mathematical model and the results of numerical modeling of...     

Trace Elements in the Products of Mud Volcanoes in the Northwest Caucasus

Doklady Earth Sciences - Comparison of the distribution of trace elements in the products of mud volcanoes of the Northwest Caucasus, Dzhungar Basin, and Andaman Islands shows that these products...     

Patterns of the Distribution of Rare-Earth Elements in Waters of Mud Volcanoes

Doklady Earth Sciences - The original data on the distribution of rare-earth elements in waters of mud volcanoes of Sakhalin Island, Taman Peninsula, and Azerbaijan are presented. It has been shown...     

利用Munk公式和海底反射走时反演深海水体速度:理论

为解决深海水体速度建模问题，建立了两个利用Munk公式和海底反射走时反演深海水体速度的反演理论，一个是射线走时反演理论，另一个是波动方程走时反演理论。具体地讲，是建立了地震波走时关于Munk参数的Fréchet导数和海森矩阵公式。为得到射线走时的Fréchet导数和海森矩阵，利用了3种不同的方法，即变分法、微扰法和Taylor级数展开法。这3种方法在理论上完全等价，其最终结果也完全相同。为得到波动方程走时反演理论中的Fréchet导数和海森矩阵，利用复合函数求导的链式法则对文献中的有关结果进行变换，以将其从面向速度本身的Fréchet导数和海森矩阵变换为面向Munk参数的Fréchet导数和海森矩阵。此外，还提出了实现利用Munk公式和海底反射走时构建深海水体声速剖面的5个策略，包括利用解析公式计算海底反射走时的由下至上的射线追踪策略，选用最简单的海底边界条件把数值模拟区域限定为水体的策略，用已知的深海声道轴深度和交替反演策略将四参数反演问题转简化为单参数反演问题的策略，由点到面，利用一维声速剖面公式实现深海水体的维速度建模的策略，以及用最简单的算法实现走时反演的最优化计算策略等。与常规走时反演相比，利用Munk公式进行的海底反射走时反演最多只需要反演4个参数，并可利用交替反演将四参数反演化为单参数反演，大大地减少了走时反演的计算量。     

Strontium Isotopic Composition in Carbonate from Breccias of Mud Volcanoes of Azerbaijan

In 13 out of 14 samples of carbonate xenoliths from mud volcanic breccias of Azerbaijan, the 87Sr/86Sr values (0.70675–0.70823, 87Sr/86Srmd = 0.7073 ± 0.0005) are within the same limits as in the volcanic waters (Bujakaite et al., 2019). Genetically, they can be associated both with Mesozoic carbonate and saline deposits or with Cenozoic volcanosedimentary strata. Similarity of the Sr isotopic composition with isotopic values in carbonate extracts from terrigenous rocks of the Maikop Formation was noted only in the calcite sample from the Cheildag Volcano (87Sr/86Sr = 0.71047). The most interesting results with the lowest Sr ratios were obtained for carbonate fragments from breccias of the Byandovan Volcano. The combination of low δ13C values (down to –49.2‰), high Sr contents (up to 3108 μg/g) and 87Sr/86Sr (0.70675‒0.70690) values typical of the Late Jurassic brings them closer to caprocks of salt domes of Jurassic oil-bearing formations in the western United States.     

Nonlinear Inversion of Potential-Field Data Using an Improved Genetic Algorithm

The genetic algorithm is useful for solving an inversion of complex nonlinear geophysical equations. The multi-point search of the genetic algorithm makes it easier to find a globally optimal solution and avoid falling into a local extremum. The search efficiency of the genetic algorithm is a key to producing successful solutions in a huge multi-parameter model space. The encoding mechanism of the genetic algorithm affects the searching processes in the evolution. Not all genetic operations perform perfectly in a search under either a binary or decimal encoding system. As such, a standard genetic algorithm (SGA) is sometimes unable to resolve an optimization problem such as a simple geophysical inversion. With the binary encoding system the operation of the crossover may produce more new individuals. The decimal encoding system, on the other hand, makes the mutation generate more new genes. This paper discusses approaches of exploiting the search potentials of genetic operations with different encoding systems and presents a hybrid-encoding mechanism for the genetic algorithm. This is referred to as the hybrid-encoding genetic algorithm (HEGA). The method is based on the routine in which the mutation operation is executed in decimal code and other operations in binary code. HEGA guarantees the birth of better genes by mutation processing with a high probability, so that it is beneficial for resolving the inversions of complicated problems. Synthetic and real-world examples demonstrate the advantages of using HEGA in the inversion of potential-field data.     

准噶尔盆地南缘泥火山活动及其伴生油苗的地球化学特征和意义

文中对准噶尔盆地南缘乌苏四棵树和独山子泥火山的构造背景进行了分析,指出其形成主要是由于天山北缘中新生 代沉积层中地势高低造成的水压差和地层层间压力差,导致丰富的地下水沿着背斜顶端发育的断裂带上升,与通道周围的 泥质岩石相遇,泥浆形成并喷出地表而成为泥火山。论文还对四棵树和独山子泥火山的伴生油苗进行了全油色谱和生物标 记化合物研究,对比相关烃源岩地球化学特征及前人有关研究成果,指出油样有机质均处于成熟阶段,油源可能是侏罗系 与古近系烃源岩的混合产物。研究结果对探索该区泥火山的成因和油气成藏条件具有重要意义。     

直流电阻率测深中二维反演程序对三维数据的近似解释

直流电阻率测深剖面数据解释最好的方法是二维反演，这是由于它反演速度快，而三维反演则需要很多的实测数据、很长的计算时间。而且通过对几种三维模型测深数据的二维反演结果的研究，发现尽管对无走向的良导矿体，二维反演方法所圈定的异常中心与真实矿体中心有一定的误差，但基本上还是能反映矿体的真实形态和中心位置。当矿体具有一定的走向长度时，则无论对高阻矿体还是良导矿体二维反演的效果都很好。     

羌塘盆地岩石物理力学特性分析及其孔壁稳定技术

羌塘盆地是青藏高原年平均地温最低、冻土层相对较厚的地区,所处的水文地质及工程地质环境极其复杂。由于勘探程度低,深孔钻探的实钻资料较少,缺乏对该区深部岩层的岩石物理力学特性研究。因此,结合地球物理测井技术、取心和实验测试结果对QK-7孔钻遇地层岩石物理力学参数进行分析,并对冻土带异常孔隙水压力极复杂地层孔壁稳定泥浆工艺技术进行总结和探索,以期为羌塘盆地油气资源战略开发深孔钻探的顺利实施提供基础理论支持。