| In recent years,with the increase of exploration in the Pearl River Mouth Basin,exploration targets have shifted from Neogene to deep Paleogene.With the shift of conventional oil and gas exploration direction from shallow to deep,it is of great significance to explore high-quality deep reservoirs for commercial oil and gas discovery.Deep oil and gas reservoirs can be the discovery of large-scale and high-quality reservoir development that is closely related.The primary intergranular pores are developed in the Paleogene reservoirs with a buried depth of nearly 4000 m in Lufeng Sag.Previous studies on the formation mechanism of high-quality reservoirs are limited to the control of sedimentation and diagenesis,and lack research and analysis on the control of the geothermal environment,burial mode,and sand body thickness,which restricts the further progress of Paleogene oil and gas exploration.Therefore,this paper takes the Paleogene clastic reservoir in Lufeng Sag as the research object,and analyzes the sedimentary reservoir characteristics of the high-quality reservoir in the study area based on the rock thin section,scanning electron microscope,reservoir physical properties,drilling,and logging analysis data system.On the basis of the characteristics,combined with the geothermal environment,sand body thickness,burial mode,and late dissolution and transformation,the genetic mechanism of high-quality reservoir are analyzed,the development mode of high-quality reservoir is established,and the distribution of highquality reservoir in different sag zones in the study area is studied.The main conclusions are as follows :(1)The high-quality reservoirs of the Enping Formation in Lufeng Sag are mainly composed of feldspar lithic quartz sandstone,and the Wenchang Formation is mainly composed of lithic quartz sandstone.(2)The rocks in Lufeng sag have high compositional maturity.Primary intergranular pores are the main reservoir space,while secondary pores are less developed.(3)The Enping formation reservoir belongs to low-medium porosity and low-medium permeability reservoir.(4)Five main controlling factors are summarized for the primary pore development of highquality reservoirs in the Lufeng Depression.Under strong hydrodynamic force,the rock particle sorting and grinding of underwater distributary channel sand body in braided delta is better.The content of the impurity base in the reservoir is small,which can effectively slow down the damage of reservoir pores caused by late compaction.The Paleogene Wenchang Formation developed a large set of thick sandstone bodies,and the calcareous cementation formed at the top and bottom of the thick sandstone reservoir can effectively slow down the compaction.The early shallow burial plays a positive role in the development of high-quality reservoirs in the Lufeng sag,mainly because a set of compaction skeletons is formed in the early shallow burial environment,which can effectively resist the destruction of reservoirs space by compaction.Lufeng sag is located in a relatively low geothermal environment,which can slow down the time when the reservoir enters the middle diagenetic stage and can slow down the overburden compaction.(5)The organic acids produced by the mature source rocks of the third and fourth member of The Wen Formation corroded the easily corroded particles in the reservoir.The organic acids corroded the secondary pores to improve the reservoir capacity and reservoir quality.(6)The Enping Formation in Lufeng sag is the main reservoir with high quality due to its shallow burial depth and weak compaction damage.The high-quality reservoirs in Wenchang Formation are mainly developed in the fifth and sixth members of the Wenchang Formation.Through the method of main controlling factor superposition,it is shown that the potential oil and gas enrichment target areas are the west area of east LF13 sag,east area of west LF13 sag,and northeast area of LF7 sag. |
