Prediction To Fracture Distribution And It's Accumulation Significance In Ta,nan Depression Base Rock Buried Hill

In order to research fracture of Ta,nan depression base rock buried hill and it's significance of accumulation,core is first used to make the research on the development characteristics of fracture.It shows that the main type of fracture is tectonic fracture,including tensile fracture and shear fracture;the most line density of fracture comes to 55/m;aperture of fracture mainly distribute between 0.1-1mm;the orientation of fracture is more in mid-high angle,accounting for 51%of all fractures;the filling mineral of fracture such as carbonate(ferrocalcite,ferrodolomite),quartz,gypsum,pyrite,mud etc.are commonly seen.According to core observation and thin section,intersecting of fracture and filling characteristics is confirmed,three cause of formatio of fracture are divided,the first is calcite and dolomite filled,the second is dolomite filled and the third is the later period,quartz and gypsum filled.Three types of filled situation,fully filled,half filled and not filled.Fully filled fracture comes to 51%,half filled and not filled fracture account for 49%.The early formed fractures controlled by early active faults are more easily filled,most are filled fractures.The late formed fractures controlled by faults are half and not filled.A further research on the controlling factors of fracture development has been made by physical modeling expreriment.It's showed that,besides fault and lithology,the development of fracture are affected by thickness of formation,diagenesis pressure,cement extent and the content of mudstone and sandstone.The development of fracture comprehensive index is established by well logging materials,fractures are identified by responding characteristics of well loggging curves combined with core hole.The higher the fra is,the more the fracures develop and vice versa.For big aperture fractures,fac distribute in 0.6-0.3,most are over 0.2,mean value is 0.216;for half filled fractures,fra distribute in 0.0-0.16,most in 0.1-0.16,and mean value is 0.105;for filled fratures,fra distribute in 0.0-0.1,mean value is 0.049.Fractures are the main reservoir space in Ta,nan depression based rock buried hill,all the oil found till now accumulate in fractures.Using MVE software,the distribution of fratures are predicted.it's considered that fractures mainly distribute in higher strain and curvature area,fractures develop near faults,between uplift and low-lying in the west,strain near 19-37 well and 19-23 well in the northwest is higher,deformation of stratum is higher.The strain in the northeast is low,fractures don't develop.Wells located in fracture most developed area are 19-7 well in the east,19-12 well,19-26 well,19-15 well,19-25 well,19-24 well,19-8 well in the southwest uplift zone,wells located in fracture more developed area are 19-30 well and19-40 well in the western ramp region,and 19-32 well and 19-36 well in central uplift zone.Fracture don't develop in the eastern low-lying zone,such as 19-38 well.All the fracture developed area are favorate target for Ta,nan depression based rock buried hill.