Reservoir Characteristics Of Chang4+5and Chang6Formationand Its Effect On The Oil Accumulation In Zhao’an-Yanhewan Block Of The Ordos Basin

This paper detailedly studies the stratigraphy, sedimentation, reservoir and oil-bearingcharacteristics of Chang4+5and Chang6pay zones in Zhao’an-Yanhewan block, with thehelp of modern sedimentary, reservoir geology, lithofacies paleogeography and other theoriesand methods, toghether with multiple kinds of tests and analysis approaches, thus resulting inthe surmmary of distribution mode of good-quality reservoirs. Reservoirs of Chang4+5, andChang6belong to the delta front, where develops the underwater distributary channels. Basedon the physical analysis data, this area is defined as low porosity, low permeability reservoir.The latter dissolution, to some degree,increases the reservoir porosity and improves thereservoir permeability, making a minority of low permeable sandstones maintaining betterstorage property. The reservoirs in the study area are classified into4catergires, based ondifferent kinds of parameters. In a nutshell, we can conclude that the oil-bearing factors ofreservors in Zhao’an-Yanhewan blockare mainly controlled by sedimentation, physicalproperty and diagenesis, etc, combined with reservoir sedimentary microfaciesm sand bodydistribution, physical property, as well as core observation, cast thin section, cathodeluminescence, mercury injection and oil-testing data.