摘要
随着中国非常规、超低渗油气资源的大力开发,压裂监测技术迎来重大发展机遇。电磁法在地球物理探测方面具有成本低、时效性强、探测深度大等优点,但面对大深度压裂环境,电磁压裂监测技术的可行性亟须论证。基于充电导体和电偶极源扩散电磁场理论,首先构建了不同深度和不同长度下的裂缝压裂模型,分析了各模型的地面总场及异常场的电磁响应特征。分析结果表明:利用井地电磁法进行压裂监测时,观测总场对裂缝长度增加引起的电磁响应不敏感,异常场存在低值带;深度为4000 m时,电磁异常小于1%,深度越大异常场衰减越严重,且相邻测点间异常场的绝对值与深度呈负相关,电磁法压裂监测技术难以兼顾探测精度与探测深度。然后,通过建立压裂监测物理模型,分析实测数据电磁异常曲线特征,验证了理论计算的正确性。最后,结合前人理论成果和实践经验,提出了一种井中激发—地面接收的测网式电磁法压裂监测观测系统,对测区范围与测点间距进行合理约束,系统具有野外施工简捷、监测深度大等优势,为电磁法压裂监测提供了新的发展方向。
With the vigorous development of unconventional and ultra‑low permeability oil and gas resources in China,fracturing monitoring technology has ushered in a major development opportunity.The electromagnetic method has the advantages of low cost,high timeliness,and large exploration depth in geophysical exploration.However,in the face of large‑depth fracturing environments,the feasibility of electromagnetic fracturing monitoring technology needs to be demonstrated urgently.Based on the theory of charged conductor and electric dipole source diffused electromagnetic field,this paper firstly constructs fracturing models with different fracture depths and lengths and calculates the electromagnetic response characteristics of the total ground field and anomalous field under different models.The calculation results show that when the borehole electromagnetic method is used for fracturing monitoring,the observed total field is not sensitive to the electromagnetic response caused by fracture length increase,and the abnormal field has a low value zone.When the depth is 4000 m,the electromagnetic anomaly is less than 1%.Larger depth indicates more serious attenuation of the abnormal field.Moreover,the absolute value of the abnormal field at adjacent measuring points is negatively correlated with the depth,and the electromagnetic fracturing monitoring technology is difficult to balance detection accuracy and detection depth.Then,through the physical model of fracturing monitoring,the characteristics of the electromagnetic anomaly curve of the measured data are analyzed,and the results verify the correctness of the theoretical calculation.Finally,a network‑type electromagnetic fracturing monitoring and observing system with excitation in the well and reception on the ground is proposed by combining the theoretical achievements and practical experiences of the previous researchers,which imposes certain constraints on the range of the measurement area and the spacing of the measurement points.The system has the advantages of efficient field operation and large monitoring depth,which provides a new development direction for electromagnetic fracturing monitoring.
作者
李帝铨
李富
张乔勋
黄亚
别勇杰
胡艳芳
LI Diquan;LI Fu;ZHANG Qiaoxun;HUANG Ya;BIE Yongjie;HU Yanfang(Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Ministry of Edu-cation,Central South University,Changsha,Hunan 410083,China;Key Laboratory of Non-Ferrous and Geological Hazard Detection,Changsha,Hunan 410083,China;School of Geosciences and Info-Physics,Central South University,Changsha,Hunan 410083,China;Hunan Geosun Hi-technology Co.,Ltd.,Changsha,Hunan 410208,China)
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2024年第1期151-159,共9页
Oil Geophysical Prospecting
基金
国家自然科学基金项目“南方海相页岩气电磁法识别与预测方法研究”(41874081)资助。
关键词
充电导体
电磁监测
探测深度
低值带
水力压裂
charging conductor
electromagnetic monitoring
detection depth
low value zone
hydraulic fracturing
作者简介
李帝铨,教授,博士生导师,1982年生,2005年获中南大学地质资源与地质工程专业学士学位,2010年获中国科学院固体地球物理学专业博士学位,2010年入职中南大学,主要从事电磁法探测理论与方法研究;李富,湖南省长沙市岳麓区麓山南路932号中南大学地球科学与信息物理学院,410083。Email:Li_Fu001@csu.edu.cn。
