The Petrogeologic Characteristics And Reservoir Prediction Of The Upper Formation Of Guantao Group In Chengdao Oilfield

ChengDao oil field is a big anticine structure which developed basing on pretertiary sub-mountain. It surrounded by BoZhong depression and ChengBei sag with good reservoir-forming condition. Guan Tao group oil layers are the major exploited formations of ChengDao oil field, its reservoir sand is fluvial deposition, and the reservoir is controlled by structure and lithology. Making it clear that Petroleum Geologic Characteristics and sand-distribution of Upper GuanTao group is the key factor for the successful exploitation of Upper GuanTao group. On the basis of previous research works, new exploration wells, new appraisal wells and 3D seismic material are added to new research work in which rock and mineral, sedimentary facies and oil bearing characters are studied deeply by employing the methods of petroleum geology, sedimentary geology and reservoir geology. The results of reservoir prediction on fluvial sandbody in the upper of formation of Guantao group obtained by using coherent analysis and acoustical impedance inversion bring good effect to the exploration and development of Chengdao oilfield.According to rock and mineral analysis, the formation consists dominantly of detrital feldspathic fine-sandstone with medium and silt sandstone secondly. Lithologically, the content quartz is lower than those of feldspar and detritus, and the cement is dominated by clay, which gives the feature of low compositional maturity and low textural maturity. Due to low burying depth and weak diagenesis, the formation is loosely solidified, which shows an immature stage of diagenesis. Analysis of experiment material shows that the poretexture is kind of coarse-pore and coarse-throat with high porosity and high permeability.The lower part of formation, that is, 6-7th sand group, with the deposition of braided river is different with the upper, l+2-5th sand group, which belongs to deposition of meandering river. Generally, there are four sub-facies shown in the upper of formation of Guantao group; And, five micro-facies.Chengdao oilfield is kind of litho-structure oil gas reservoir with good conditions of source-keep-seal and abundance reserves.The technique of reservoir prediction using coherent analysis and acoustical impedance inversion is characterised by high resolution and good results, which has taken an important role in the placement of exploration well and development well, and got good economic and social effect.