Reservoir evaluation and fracturing transformation of Tun 1 well in Yichuan sag

Through the systematical evaluation of Tun 1 well fracturing layer in Yichuan sag in Luoyang-Yichuan basin,it is thought this layer has the features of low porosity,low permeability,and extremely low yield.Nuclear magnetic logging effective porosity is 3.3%,permeability is 0.645×10-3μm2.Imaging logging indicates fracturing development,which is matrix porosity and fracturing reservoir.Oil testing shows the natural gas capacity is only 53 m3/d,Through secondary shut-in well pressure recovery data qualitative analysis,it is thought fracture developed,matrix porosity permeability is bad,using conventional fracturing transformation to increase yield is poor.In this paper,using fracturing technology to optimize perforation mode,pump string,construction scale,fracture parameters and adopting fracturing scheme of high emissions,high fluid volume,low viscosity,low sand ratio to form more fracture and complex fracture and increase discharge area.Through unconventional fracturing transformation,10 mm nozzle spray,hydraulic 3.1-3.5 MPa,daily gas capacity is 6600-7000 m3,which realize the important breakthrough for the oil and gas exploration of Luoyang-Yichaun basin.