Feasibility Analysis of Existing Recoverable Oil and Gas Resource in the Palaeogene Shale of Dongying Depression
东营凹陷古近系泥页岩中存在可供开采的油气资源

The exploration practice in the North America suggests that shale gas as an unconventional natural gas resource,is a kind of current alternative energy resource.According to measured data of geochemistry,mineral,logging,drilling and seismogram on the Palaeogene strata in the Dongying depression,the shale in the lower Es3 and upper Es4 is characterized by large thickness,high abundance of organic matter,favorable types and wide range of thermal maturity.It has similar geological and geochemical characteristic comparing with the gas-generated shale in the North America.The shale in this area has high content of quartz and carbonate as well as less than 50% clay content.In addition,the shale has the brittleness and generally developed micro\|fractures,which are useful to exploration of shale gas.The gas logging analysis on the shale of lower Es3 and upper Es4 shows the abnormal phenomena.The well kick and leak occurred frequently during well servicing,indicating the existence of gas.The light hydrocarbon abundance in the two setting of head space gases increase with depth,with C5-7/C1-4 value less than 0.15 while the depth is more than 3 400m.According to correlation of light hydrocarbon composition of head space gases and gas-to-oil ratio as well as buried depth,the exploration of the shale gas reservoir in the Dongying depression should be oil and gas concurrent exploration,when the buried depth is less than 3 400m,in contract that the exploration should give priority to shale gas reservoir if it is more than 3 400 meters.Therefore,we proposes that it should be a remarkable notable and risk invest in new exploitation field since the Paleogene shale in the Dongying depression exists great recoverable oil and gas resource.