Study On Karstic-fault Description Of Ordovician Yijianfang Formation In Yueman Block Of Halahatang Oilfield

Halahatang Oilfield Yueman Block is a large Ordovician marine carbonate reservoir located in the Tarim Basin,with rich oil and gas resources and development potential.With the deepening of exploration and development and the continuous understanding of the carbonate oil and gas enrichment laws,a new concept of“Karstic-fault”reservoirs has been gradually introduced.The shape of the karstic-fault is irregular,controlled by the fracture.So the study of fault solution oil and gas reservoirs is divided into two major modules--fault understanding and karstic-fault description.The Paradigm software is used to process the three-dimensional seismic data in the study block by eigenvalue coherent volume processing,and the fault distribution characteristics of the study area are obtained after fine interpretation.There are mainly five large fault zones from the Ordovician Yijianfang formation to the Cambrian and many small faults that are associated with or formed by later small tectonic movements.In terms of interpretation results,the Yueman block faults are divided into first-level faults,second-level faults,and third-level faults according to the scale of fault development.The first-level faults are the main research objects.The development of faults in the study area has an important impact on the formation of karstic-fault.First,the faults from fault to Cambrian communicate with the source rocks and serve as migration channels for oil and gas;Second,small faults act as channels for underground hydrothermal fluids and acidic fluids carried by hydrocarbons,connecting carbonate reservoirs and increasing connectivity.Based on the understanding of the faults in the study area,further analysis of the formation mechanism of karstic-fault in the study area,in which sedimentary environment,tectonic action and karstification are the controlling factors for the formation of fault solution.A large amount of data and production data are compared to summarize the seismic,drilling and logging identification marks of the broken solution.According to the pore size,the storage space of karstic-fault is divided into macro storage space and micro storage space for detailed description.It is found that the best production effect of macroscopic storage space in the study area is cave storage space,followed by pore storage space.After a preliminary understanding of the karstic-fault,Jason software is used to finely sculpt the karstic-fault and divide the karstic-fault into three categories: Class I,Class II and Class III karstic-fault.Among them,Class I and Class II karstic-fault are the focus of exploration and development.Finally,combined with production data for dynamic analysis to solve the problem of connectivity,summarized the rule that the height of the oil column on the main fault is generally large and the karstic-fault is well developed.The research results have great guiding significance for the development of Yueman Block and surrounding blocks in the future.