The Reservoir Characteristics And Prediting Favorable Blocks Of Fuxian Formation In Dingbian Area

Taking sedimentary petrology, structural geology, petroleum geology,geological logging and other related subjects as theory foundation andusing logging, drilling, logging, coring, geochemistry and other materialsto study on sedimentary characteristics, reservoir characteristics andaccumulation factors， this paper comprehensive analyses controllingfactors of reservoir and predicts favorable blocks. This paper has obtainedthe following main achievements and knowledge:(1) Using cycle of sedimentation, lithology thickness contrast, FuxianFormation is fine divised and correlation studied in isochronousstratigraphic framework. Fuxian Formation in early of Jurassicsedimentary formation are mainly incition of the river and valleysediments. In this period, The sedimentary mainly level up ancientlandform formed by the Indosinian Movement. The deposition in theperiod of Fuxian, old channel of NingShan insied river cut into a few layers. In DingBian area,NingShan ancient river was through the area, the deepestcut through the old channel length reached to the formation of Chang3,which has provided the favorable channels for oil and gas generated fromTriassic strata migrate to Jurassic Stratigraphic.(2Fuxian Formation mainly is braided river sedimentation, mainlydevelopment river filling, floodplains microfacies. Fuxian Formation’schannel can reach to10-13km.Channel sand body is mainly showing anorth-south extent band in plane. In some areas, rivers in the event ofmergers and branches form a braided or mesh patterns, obviouslycontrolled by Sedimentary Micro-facies. Fuxian Formation’s reservoirphysical properties is good, porosity is main distributed between15%~17%; Permeability is mainly distributed in the range of10×10-3μm2～65.23×10-3μm2.(3) Researches show that the diagensis of reservoir sandstone ofFuxian formation mainly experienced is compaction&pressure-solution,dissolution, cementation, catastasis, etc. According to comprehensiveanalysis of buried history’s recovery and diagenesis, sandstone of FuxianFormation is now in the A stage of later diagenesis. During the process ofrock-forming, the compaction&pressure-solution reservoir porositymakes original porosity of reservoir reduced by25%,and68%originalporosity has been lost. Cementation makes reservoir porosity3%reduced,and7%original porosity has been lost. Dissolution has played a critical factor in improving sandstone’s physical property and porosity hasincreased from11%to17%in the Late Jurassic-Early Crataceous.(4) Fuxian formation’s reservoir permeability of the heterogeneity isstrong. According to electrical measurement explain and a lot of porositymaterial’s comprehensive analysis, the sand body form by the same river,the reservoir physical property is different,in horizontal direction of thereservoir physical property changes are also great. The reservoir sand bodyin planar distribution and property have also become different, thus makethe reservoir heterogeneity further strengthened.(5) Based on the research in comprehensive, combing controllingfactors of reservoir formation and the test of oil drilling, logginginterpretation result, predicted two favorable prospecting areas.