摘要
Shale gas reservoirs have large burial depths,thin thickness,and low resistance,which lead to problems with weak surface observation,abnormal information,and multiple inversion solutions.The traditional electromagnetic method cannot effectively identify information from deep,low-resistance thin layers in terms of detection depth and accuracy.Wide field electromagnetic method(WFEM)with large depth and high precision has become the main method for deep earth exploration.This method has been widely used in the exploration of deep oil and gas energy,as well as mineral resources.However,an in-depth analysis of the various factors that affect the deep detection ability of WFEM is lacking.Therefore,the analysis of system parameters has significant theoretical importance and practical value for studying the effectiveness of WFEM in deep-layer identification.In this study,a multilayer geoelectric model is established in this study using the measured well data.The influence characteristics of different observation system parameters on the resolution of specific deep-seated targets under the WFEM_E-Ex mode are analyzed in detail through forward modeling and inversion.Results show that the resolution ability of WFEM for deep,low-resistance thin layers is affected by factors such as transceiver distance,target layer thickness,and resistivity difference between the target body and the surrounding rock,but the influence range differs.This study analyzes the influence characteristics of various system parameters.It provides targeted work scheme design and feasibility analysis for deep shale gas exploration.It also offers an important theoretical basis for optimizing construction schemes and improving the recognition ability of WFEM for deep,low-resistance targets.
页岩气层具有埋藏深度大、厚度薄、低电阻等特征,引起地表观测异常信息弱及反演多解性等问题,传统电磁法在探测深度、探测精度和探测准确度方面难以有效识别深部低阻薄层信息。大深度高精度广域电磁法(Wide Field Electromagnetic Method,WFEM)已成为深地探测的主要方法之一,被广泛应用于深部油气能源及矿产资源勘探,但目前仍缺少对影响广域电磁法深部探测能力的诸多因素进行深入研究与分析。因此,分析野外系统参数对影响广域电磁法深部薄层识别能力的有效性研究具有重要理论意义和实用价值。本文根据实测井资料,建立多层地电模型,通过正演和反演,详细地分析了广域电磁法E-Ex模式下的不同观测系统参数对特定深层目标体的分辨能力的影响特征。结果表明,发收距、目的层厚度、目标体与围岩介质电阻率差异等因素,均会影响广域电磁法深部低阻薄层的分辨能力,但其影响幅度各不相同。本文分析各种系统参数的影响特征,为深部页岩气层探测提供有针对性工作方案设计及可行性分析,对优化施工方案,提高广域电磁法对深层低阻目标体的识别能力,具有重要的理论依据。
基金
supported by the Jingdezhen Science and Technology Plan Project(No.20234SF005)
the Jingdezhen University Science and Technology Project(No.2023xjkt-02).
