储层断裂高分辨预测及连通性评价方法研究与应用

High-resolution fault detection and connectivity evaluation method and its application

1.成都理工大学“地球勘探与信息技术”教育部重点实验室,四川成都 610059;
2.电子科技大学资源与环境学院,四川成都 611731;
3.电子科技大学长三角研究院,浙江湖州 313000

1. Key Laboratory of Ministry of Education,Geo-Exploration and Information Technology,Chengdu University of Technology,Chengdu 610059,China;
2. School of Resources and Environment,University of Electronic Science and Technology of China,Chengdu 611731,China;
3. Yangtze Delta Region Institute(Huzhou),University of Electronic Science and Technology of China,Huzhou 313000,China

为了提高断裂预测精度和分辨率,分析储层断裂连通性,提出基于高斯滤波拉普拉斯(the Laplacian of a Gaussian filter,LoG)算子的断层增强方法、基于特征向量的断层细化方法和基于三维稳态饱和流动方程的断层连通性方法相结合的储层断裂预测及连通性评价方法。将该方法应用于威远龙马溪组页岩储层断层增强和断层细化的处理,提高了地震资料的信噪比,改善了横向和垂向上的分辨率,突出了微、小断裂的细节特征,使目标储层的断裂特征刻画得更清楚、全面,增强和细化处理后的属性对断裂识别的分辨率和精度都明显优于相干属性;断层连通性评价方法的应用突出了目标储层段的连通断层,同时连接了小断层,并结合该储层段的孔隙度预测结果,将储层断裂连通性划分为3个区间,得到有效的评价认识,即:目标储层段断层、中小尺度断裂发育,储层断裂整体连通性较好,可以作为天然气的储集空间和运移通道。

Identifying fault system is the first step in seismic interpretation and a key component of formulating exploration and development strategies;it is of great significance for the early,middle,and late stages of exploration and development.Attribute extraction using seismic data with high resolution and high signal-to-noise ratio is the key to low-relief structure interpretation and fault detection.High-precision evaluation results of reservoir fault connectivity can effectively guide and formulate reasonable development technology plans,and improve oil and gas reservoir recovery efficiency.When oil and gas reservoirs are deeply buried and the underground geological conditions are complex,the quality of seismic data will be reduced.In this case,directly using methods based on seismic data discontinuity (e.g.coherence cube technology) to identify faults will lead to problems such as low resolution,imprecision,and insufficient description of faults connectivity;thus it is difficult to meet the needs of fine exploration.In order to improve the accuracy and resolution of fault prediction and analyze the connectivity of reservoir faults,we propose a method of reservoir fault prediction and connectivity evaluation,which combines fault enhancement based on a LoG operator,fault refinement based on feature vector,and fault connectivity assessment based on three-dimensional steady-state saturation and flow equation.As per a case study of Longmaxi shale reservoirs in Weiyuan,improved signal-to-noise ratio and horizontal and vertical resolution by fault enhancement and refinement facilitate detailed interpretation of small fractures;seismic attributes extracted after processing perform better than coherence attribute in fault identification with improved resolution and precision.Connected faults are highlighted using the connectivity evaluation method,and small faults are connected.According to above results and porosity prediction,fracture connectivity is divided into three types and evaluated separately.In conclusion,target reservoirs are rich in faults and medium- to small-scale fractures with good connectivity,which may function as the reservoir space and migration pathways of gas.

国家自然科学基金面上基金(42074160)和四川省自然科学基金项目(2023NSFSC0255)共同资助。

10.12431/issn.1000-1441.2024.63.04.013