Identification And Evaluation Of Tight Reservoir Fractures In The Anpeng Deep System Of Biyang Depression

The dense exploration target layer of the Anpeng deep strata in Biyang Depression is located in the three oil groups VII,VIII and IX of the third section of the He taoyuan Formation.The total resources are between 2.7 and 3.4 million tons,and the current proven reserves are 1.9 million tons and has a great exploration potential.However,the fracture characteristics of tight sandstones are complex,and there are some differences between the types and distribution laws of fractures and conventional reservoirs.At present,the method for evaluating the fracture logging of tight reservoirs in the study area has not been established.Therefore,this paper conducts comprehensive fracture log evaluation for the target layer of the study area,which provides basis and guidance for the development of well location in the later stage.In this paper,using geological data,core data,well logging data,test data,and production dynamic data,the fracture characteristics are first described,Combined with conventional logging fracture response feature method,hole seepage intersection chart method,wavelet high frequency attribute method and electric imaging human-computer interaction method to identify fractures and calculate relevant fracture parameters.Then,the effectiveness of fractures was evaluated by combining stress matching method,electro-imaging logging and Stoneley wave.Finally,the research results of sedimentary facies research,3D seismic prediction fracture,diagenetic evolution and effective reservoir distribution research were carried out.The fracture distribution rules of the three oil groups,VIII and IX were predicted,and guidance and suggestions for the development of well location were made.The study found that the fractures in the study area are dominated by high-angle structural fractures and diagenetic fractures,and some low-angle fractures and mesh joints are also present,and the dissolution phenomenon is common.There are four groups in the development of fractures,among which the EW group is the most developed,followed by the NE-SW and NW-SE groups,and the SN group is the least developed.By establishing the permeability increase coefficient I_K,the wavelet high frequency property and the electrical imaging human-computer interaction method,the fracture can be well recognized.According to the angle relationship between the direction of the maximum horizontal principal stress and the direction of the fracture,it is found that the fracture is less than 10°and the fracture is the most effective,and the angle is greater than 15°.The effective fracture porosity lower limit calculated by imaging logging is 0.85%,and the lower limit of fracture width is 0.4mm.Based on the fracture type,fracture strength,fracture level and fracture combination,the fracture evaluation system of the tight sandstone reservoir of the Anpeng deep stratum in Biyang Depression was established.Through the method of 3D seismic data attribute fusion,it is predicted that the fracture of the VII oil group develops in the southeast,the fracture of the VIII oil group is developed in the southeast and northwest,and the fracture of the IX oil group is developed in the south and east.Finally,three favorable target areas of the VII oil group were predicted,which were distributed in the northwest,central and southeast of the study area,with an area of 0.45km~2,2.01km~2and 0.45km~2respectively.The VIII oil group has a favorable target area with an area of 3.02km~2,which is distributed in the north-southeast direction.The IX oil group has a favorable target area,which is distributed in the middle of the study area and has an area of about 1.63 km~2.