Logging Evaluation Of Upper Paleozoic Stratum In Mulei Sag,Junggar Basin

The main body of the Mulei Sag is located in the Zhundong Uplift in the Junggar Basin,with Qitai Uplift in the north,Bogda East Wing in the south,and Gudong Uplift in the west.The overall degree of exploration in this area is relatively low,and there are few relevant research data for formation evaluation,source rock and reservoir evaluation,and oil,gas and water evaluation.The lack of research data has brought greater difficulty to the evaluation of oil and gas exploration and development in the block.This research focuses on the evaluation and research of the upper Paleozoic stratigraphic development characteristics,source rock and reservoir characteristics,oil,gas and water characteristics of the upper Paleozoic in the Mulei Sag based on the logging data of this block,which is the next step for the block.Provide data reference for exploration deployment.Through the collection and sampling of logging data from exploration well Mucan 1,Mulei 1 and Mulei 2 deployed in the Mulei Sag of Junggar Basin in recent years,combined with paleontological sporopollen,quantitative fluorescence,and rock pyrolysis Logging experiment analysis methods such as geochemistry,nuclear magnetic resonance,scanning electron microscopy,cast thin slices,fluorescent thin slices,etc.,to carry out the four directions of the upper Paleozoic stratigraphic characteristics,source rock evaluation,reservoir evaluation,and oil,gas and water evaluation in the Mulei Sag understanding.(1)The Upper Paleozoic in Mulei Sag,Junggar Basin,only well Mulei 2 has encountered the Carboniferous Shiqiantan Formation.The stratum of Wutonggou Formation and Pingdiquan Formation showed a gradual uplift to the north,and the stratum thickness gradually decreased from south to north.The lithological combination characteristics of the upper member of the Batamayineshan Formation are consistent.The stratum in the middle section of the Batamayineishan Formation was only encountered in Well Mulei 2.The top of the lithological assemblage is dominated by argillaceous rocks with volcanic clastic rocks;the lower part is composed of igneous rocks and pyroclastic rocks with argillaceous rocks.(2)The source rocks of well Mucan 1,Mulei 1 and Mulei 2 in the Mulei Sag,Junggar Basin are all poor source rocks.The three wells compare the source rock development degree,organic matter abundance,organic matter type and maturity.On the whole,Mucan 1 well is the best,Mulei 2 is the second,and Mulei 1 is the worst.(3)The physical properties of the upper Paleozoic reservoirs in the Mulei Sag,Junggar Basin are generally ultra-low porosity and ultra-low permeability reservoirs,which are comprehensively evaluated as poor reservoirs.The poor physical properties of the reservoir are mainly due to strong compaction,which causes the destruction of primary pores and poor porosity.(4)Upper Paleozoic oil-bearing reservoirs in the Mulei Sag,Junggar Basin are mainly distributed in the Upper Carboniferous Shiqiantan Formation,Upper Permian Wutonggou Formation,and Middle Pingdiquan Formation.The uneven distribution of crude oil in the reservoir and low oil saturation indicate poor physical properties of the Upper Paleozoic reservoir in this block.The Pingdiquan Formation in Well Mulei 1 is a self-generating and self-storing lithologic reservoir,but it has not achieved industrial productivity.The main reason is the poor physical properties of the reservoir.In addition,due to the influence of tectonic movement,the formation pressure potential is reduced,and sufficient formation pressure cannot be provided,which is also the reason for the failure to realize industrial production capacity.