大地电磁与广域电磁探测油气藏电性结构方法及联合正反演

It is common knowledge that the seismic prospecting is currently an unique method that has the best exploration precision and the best exploration effect during the process of both geophysical petroleum exploration and lithologic-stratigraphic oil and gas reservoir exploration, but its exploration cost is extremely expensive, and its results are not satisfactory in some carbonate rock region or the piedmont zone. The electromagnetic method as a non-seismic prospecting method, has its unique advantages. The project puts forward a joint exploration method based on the magnetotelluric (MT) menthod and wide field electromagnetic (WFEM) method to studying the deep electrical characteristics and the structure relationship in the reservoir area. The resistivity parameter is based as the research foundation of the joint exploration method, which will take into account the observation accuracy and the differences of exploration depth and realize the geoelectric information complementarity of the joint exploration application. The spcific contents of the study are as follow: ⑴The analysis and exploration of the key technologies on the Wide Field Electromagnetic (WFEM) prospecting; ⑵ Using finite element method for the numerical simulation of complex geoelectric model, theoretically analyze the characteristic of abnormal response 、shadow effect and source overprint effect; ⑶ To carry out multi-frequencies data based on resistivity parameters Regularization Joint Inversion Method. The researth content of the project aims to explore the oil and gas reservoirs lithology of the structure and non-structural traps and the relation of hydrocarbon-bearing rock zone through a joint explaration method, to evaluate the validity of the joint exploration by a joint inversion of multi-frequencies data. The research methods and theories of the project will greatly contribute to the process of oil and gas exploration in the future.

在构造油气勘探与岩性-地层油气藏勘探中，地震勘探是目前唯一勘探精度和效果最好的方法，但其勘探成本高昂，而且在有些碳酸地区或山前地带，探测结果并不令人满意。电磁法作为非震勘探，有它独到的优势。本项目提出了基于大地电磁与广域电磁联合勘探方法研究油气藏地区深部电性特征及构造关系。联合勘探方法以电阻率参数为研究基础，兼顾观测精度与勘探深度的差异性，实现了联合应用地电信息互补性。研究内容如下：⑴广域电磁勘探关键技术的分析与探索；⑵利用有限元法对起伏地电模型的联合正演模拟的计算技术研究，综合分析异常响应特征、阴影效应及场源附加效应；⑶开展基于相同介质（电阻率参数）的多频数据正则化联合反演方法研究。本项目的研究目是通过联合勘探方法探索构造与非构造圈闭的油气藏的岩性和含油气岩地带的复杂构造关系，通过多频数据的联合反演评价方法的有效性。本项目的研究方法与理论将极大地促进未来的油气勘探进程。

在油气勘探中，地震勘探是目前唯一勘探精度和效果最好的方法，但其勘探成本高昂，而且在某些碳酸盐地区或山前地带，探测结果并不令人满意。电磁法作为非震勘探方法，有它的独到优势。为了进一步发挥电法在油气藏勘查中的作用，除应不断提高方法本身的观测技术外，还应注重数据处理与解释水平的提高。. 本项目经过项目组成员一年的共同努力研究，完成了广域电磁法的野外观测方式的对比研究工作，提出了一种改进的E-E 方式定义广域视电阻率，可以消除观测方位的影响，能够直观真实反映地电断面随深度的客观性变化。从频率域Maxwell方程组，采用四边形和三角形作为有限元算法的子单元，系统地推导出了二维介质的大地电磁法和广域电磁电磁法的有限元公式。对大型稀疏的系数矩阵采用非零元素的压缩存储，大大减少计算机内存的占用，有效地提高计算速度，实现了二维起伏地形各向异性介质大地电磁法的正演模拟的有限元分析、程序编制及模拟工作。完成了广域电磁法的2.5维的有限元分析、程序设计等工作；利用粒子群算法良好的全局寻优能力对模型参数空间进行初步搜索，然后把搜索结果最为最小二乘正则化反演初始模型进行迭代，构造出基于粒子群优化和最小二乘正则化的联合反演方法，实现了基于粒子群和最小二乘正则化的联合反演算法，编制出实用的程序。以上成果部分具有原创性，相应的成果将会在后期陆续发表。. 截止2014年12月，完成了设计任务要求。已发表学术论文5篇，其中SCI检索5篇，培养研究生6人。最新成果还在整理中，有待最近1-2年内发表。